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<H1><A NAME="SEC248" HREF="gettext_toc.html#TOC248">15 Other Programming Languages</A></H1>
<P>
While the presentation of <CODE>gettext</CODE> focuses mostly on C and
implicitly applies to C++ as well, its scope is far broader than that:
Many programming languages, scripting languages and other textual data
like GUI resources or package descriptions can make use of the gettext
approach.
</P>
<H2><A NAME="SEC249" HREF="gettext_toc.html#TOC249">15.1 The Language Implementor's View</A></H2>
<P>
<A NAME="IDX1217"></A>
<A NAME="IDX1218"></A>
</P>
<P>
All programming and scripting languages that have the notion of strings
are eligible to supporting <CODE>gettext</CODE>. Supporting <CODE>gettext</CODE>
means the following:
</P>
<OL>
<LI>
You should add to the language a syntax for translatable strings. In
principle, a function call of <CODE>gettext</CODE> would do, but a shorthand
syntax helps keeping the legibility of internationalized programs. For
example, in C we use the syntax <CODE>_("string")</CODE>, and in GNU awk we use
the shorthand <CODE>_"string"</CODE>.
<LI>
You should arrange that evaluation of such a translatable string at
runtime calls the <CODE>gettext</CODE> function, or performs equivalent
processing.
<LI>
Similarly, you should make the functions <CODE>ngettext</CODE>,
<CODE>dcgettext</CODE>, <CODE>dcngettext</CODE> available from within the language.
These functions are less often used, but are nevertheless necessary for
particular purposes: <CODE>ngettext</CODE> for correct plural handling, and
<CODE>dcgettext</CODE> and <CODE>dcngettext</CODE> for obeying other locale-related
environment variables than <CODE>LC_MESSAGES</CODE>, such as <CODE>LC_TIME</CODE> or
<CODE>LC_MONETARY</CODE>. For these latter functions, you need to make the
<CODE>LC_*</CODE> constants, available in the C header <CODE><locale.h></CODE>,
referenceable from within the language, usually either as enumeration
values or as strings.
<LI>
You should allow the programmer to designate a message domain, either by
making the <CODE>textdomain</CODE> function available from within the
language, or by introducing a magic variable called <CODE>TEXTDOMAIN</CODE>.
Similarly, you should allow the programmer to designate where to search
for message catalogs, by providing access to the <CODE>bindtextdomain</CODE>
function.
<LI>
You should either perform a <CODE>setlocale (LC_ALL, "")</CODE> call during
the startup of your language runtime, or allow the programmer to do so.
Remember that gettext will act as a no-op if the <CODE>LC_MESSAGES</CODE> and
<CODE>LC_CTYPE</CODE> locale categories are not both set.
<LI>
A programmer should have a way to extract translatable strings from a
program into a PO file. The GNU <CODE>xgettext</CODE> program is being
extended to support very different programming languages. Please
contact the GNU <CODE>gettext</CODE> maintainers to help them doing this. If
the string extractor is best integrated into your language's parser, GNU
<CODE>xgettext</CODE> can function as a front end to your string extractor.
<LI>
The language's library should have a string formatting facility where
the arguments of a format string are denoted by a positional number or a
name. This is needed because for some languages and some messages with
more than one substitutable argument, the translation will need to
output the substituted arguments in different order. See section <A HREF="gettext_4.html#SEC22">4.6 Special Comments preceding Keywords</A>.
<LI>
If the language has more than one implementation, and not all of the
implementations use <CODE>gettext</CODE>, but the programs should be portable
across implementations, you should provide a no-i18n emulation, that
makes the other implementations accept programs written for yours,
without actually translating the strings.
<LI>
To help the programmer in the task of marking translatable strings,
which is sometimes performed using the Emacs PO mode (see section <A HREF="gettext_4.html#SEC21">4.5 Marking Translatable Strings</A>),
you are welcome to
contact the GNU <CODE>gettext</CODE> maintainers, so they can add support for
your language to <TT>‘po-mode.el’</TT>.
</OL>
<P>
On the implementation side, three approaches are possible, with
different effects on portability and copyright:
</P>
<UL>
<LI>
You may integrate the GNU <CODE>gettext</CODE>'s <TT>‘intl/’</TT> directory in
your package, as described in section <A HREF="gettext_13.html#SEC213">13 The Maintainer's View</A>. This allows you to
have internationalization on all kinds of platforms. Note that when you
then distribute your package, it legally falls under the GNU General
Public License, and the GNU project will be glad about your contribution
to the Free Software pool.
<LI>
You may link against GNU <CODE>gettext</CODE> functions if they are found in
the C library. For example, an autoconf test for <CODE>gettext()</CODE> and
<CODE>ngettext()</CODE> will detect this situation. For the moment, this test
will succeed on GNU systems and not on other platforms. No severe
copyright restrictions apply.
<LI>
You may emulate or reimplement the GNU <CODE>gettext</CODE> functionality.
This has the advantage of full portability and no copyright
restrictions, but also the drawback that you have to reimplement the GNU
<CODE>gettext</CODE> features (such as the <CODE>LANGUAGE</CODE> environment
variable, the locale aliases database, the automatic charset conversion,
and plural handling).
</UL>
<H2><A NAME="SEC250" HREF="gettext_toc.html#TOC250">15.2 The Programmer's View</A></H2>
<P>
For the programmer, the general procedure is the same as for the C
language. The Emacs PO mode marking supports other languages, and the GNU
<CODE>xgettext</CODE> string extractor recognizes other languages based on the
file extension or a command-line option. In some languages,
<CODE>setlocale</CODE> is not needed because it is already performed by the
underlying language runtime.
</P>
<H2><A NAME="SEC251" HREF="gettext_toc.html#TOC251">15.3 The Translator's View</A></H2>
<P>
The translator works exactly as in the C language case. The only
difference is that when translating format strings, she has to be aware
of the language's particular syntax for positional arguments in format
strings.
</P>
<H3><A NAME="SEC252" HREF="gettext_toc.html#TOC252">15.3.1 C Format Strings</A></H3>
<P>
C format strings are described in POSIX (IEEE P1003.1 2001), section
XSH 3 fprintf(),
<A HREF="http://www.opengroup.org/onlinepubs/007904975/functions/fprintf.html">http://www.opengroup.org/onlinepubs/007904975/functions/fprintf.html</A>.
See also the fprintf() manual page,
<A HREF="http://www.linuxvalley.it/encyclopedia/ldp/manpage/man3/printf.3.php">http://www.linuxvalley.it/encyclopedia/ldp/manpage/man3/printf.3.php</A>,
<A HREF="http://informatik.fh-wuerzburg.de/student/i510/man/printf.html">http://informatik.fh-wuerzburg.de/student/i510/man/printf.html</A>.
</P>
<P>
Although format strings with positions that reorder arguments, such as
</P>
<PRE>
"Only %2$d bytes free on '%1$s'."
</PRE>
<P>
which is semantically equivalent to
</P>
<PRE>
"'%s' has only %d bytes free."
</PRE>
<P>
are a POSIX/XSI feature and not specified by ISO C 99, translators can rely
on this reordering ability: On the few platforms where <CODE>printf()</CODE>,
<CODE>fprintf()</CODE> etc. don't support this feature natively, <TT>‘libintl.a’</TT>
or <TT>‘libintl.so’</TT> provides replacement functions, and GNU <CODE><libintl.h></CODE>
activates these replacement functions automatically.
</P>
<P>
<A NAME="IDX1219"></A>
<A NAME="IDX1220"></A>
As a special feature for Farsi (Persian) and maybe Arabic, translators can
insert an <SAMP>‘I’</SAMP> flag into numeric format directives. For example, the
translation of <CODE>"%d"</CODE> can be <CODE>"%Id"</CODE>. The effect of this flag,
on systems with GNU <CODE>libc</CODE>, is that in the output, the ASCII digits are
replaced with the <SAMP>‘outdigits’</SAMP> defined in the <CODE>LC_CTYPE</CODE> locale
category. On other systems, the <CODE>gettext</CODE> function removes this flag,
so that it has no effect.
</P>
<P>
Note that the programmer should <EM>not</EM> put this flag into the
untranslated string. (Putting the <SAMP>‘I’</SAMP> format directive flag into an
<VAR>msgid</VAR> string would lead to undefined behaviour on platforms without
glibc when NLS is disabled.)
</P>
<H3><A NAME="SEC253" HREF="gettext_toc.html#TOC253">15.3.2 Objective C Format Strings</A></H3>
<P>
Objective C format strings are like C format strings. They support an
additional format directive: "%@", which when executed consumes an argument
of type <CODE>Object *</CODE>.
</P>
<H3><A NAME="SEC254" HREF="gettext_toc.html#TOC254">15.3.3 Shell Format Strings</A></H3>
<P>
Shell format strings, as supported by GNU gettext and the <SAMP>‘envsubst’</SAMP>
program, are strings with references to shell variables in the form
<CODE>$<VAR>variable</VAR></CODE> or <CODE>${<VAR>variable</VAR>}</CODE>. References of the form
<CODE>${<VAR>variable</VAR>-<VAR>default</VAR>}</CODE>,
<CODE>${<VAR>variable</VAR>:-<VAR>default</VAR>}</CODE>,
<CODE>${<VAR>variable</VAR>=<VAR>default</VAR>}</CODE>,
<CODE>${<VAR>variable</VAR>:=<VAR>default</VAR>}</CODE>,
<CODE>${<VAR>variable</VAR>+<VAR>replacement</VAR>}</CODE>,
<CODE>${<VAR>variable</VAR>:+<VAR>replacement</VAR>}</CODE>,
<CODE>${<VAR>variable</VAR>?<VAR>ignored</VAR>}</CODE>,
<CODE>${<VAR>variable</VAR>:?<VAR>ignored</VAR>}</CODE>,
that would be valid inside shell scripts, are not supported. The
<VAR>variable</VAR> names must consist solely of alphanumeric or underscore
ASCII characters, not start with a digit and be nonempty; otherwise such
a variable reference is ignored.
</P>
<H3><A NAME="SEC255" HREF="gettext_toc.html#TOC255">15.3.4 Python Format Strings</A></H3>
<P>
There are two kinds of format strings in Python: those acceptable to
the Python built-in format operator <CODE>%</CODE>, labelled as
<SAMP>‘python-format’</SAMP>, and those acceptable to the <CODE>format</CODE> method
of the <SAMP>‘str’</SAMP> object.
</P>
<P>
Python <CODE>%</CODE> format strings are described in
Python Library reference /
5. Built-in Types /
5.6. Sequence Types /
5.6.2. String Formatting Operations.
<A HREF="http://docs.python.org/2/library/stdtypes.html#string-formatting-operations">http://docs.python.org/2/library/stdtypes.html#string-formatting-operations</A>.
</P>
<P>
Python brace format strings are described in PEP 3101 -- Advanced
String Formatting, <A HREF="http://www.python.org/dev/peps/pep-3101/">http://www.python.org/dev/peps/pep-3101/</A>.
</P>
<H3><A NAME="SEC256" HREF="gettext_toc.html#TOC256">15.3.5 Lisp Format Strings</A></H3>
<P>
Lisp format strings are described in the Common Lisp HyperSpec,
chapter 22.3 Formatted Output,
<A HREF="http://www.lisp.org/HyperSpec/Body/sec_22-3.html">http://www.lisp.org/HyperSpec/Body/sec_22-3.html</A>.
</P>
<H3><A NAME="SEC257" HREF="gettext_toc.html#TOC257">15.3.6 Emacs Lisp Format Strings</A></H3>
<P>
Emacs Lisp format strings are documented in the Emacs Lisp reference,
section Formatting Strings,
<A HREF="http://www.gnu.org/manual/elisp-manual-21-2.8/html_chapter/elisp_4.html#SEC75">http://www.gnu.org/manual/elisp-manual-21-2.8/html_chapter/elisp_4.html#SEC75</A>.
Note that as of version 21, XEmacs supports numbered argument specifications
in format strings while FSF Emacs doesn't.
</P>
<H3><A NAME="SEC258" HREF="gettext_toc.html#TOC258">15.3.7 librep Format Strings</A></H3>
<P>
librep format strings are documented in the librep manual, section
Formatted Output,
<A HREF="http://librep.sourceforge.net/librep-manual.html#Formatted%20Output">http://librep.sourceforge.net/librep-manual.html#Formatted%20Output</A>,
<A HREF="http://www.gwinnup.org/research/docs/librep.html#SEC122">http://www.gwinnup.org/research/docs/librep.html#SEC122</A>.
</P>
<H3><A NAME="SEC259" HREF="gettext_toc.html#TOC259">15.3.8 Scheme Format Strings</A></H3>
<P>
Scheme format strings are documented in the SLIB manual, section
Format Specification.
</P>
<H3><A NAME="SEC260" HREF="gettext_toc.html#TOC260">15.3.9 Smalltalk Format Strings</A></H3>
<P>
Smalltalk format strings are described in the GNU Smalltalk documentation,
class <CODE>CharArray</CODE>, methods <SAMP>‘bindWith:’</SAMP> and
<SAMP>‘bindWithArguments:’</SAMP>.
<A HREF="http://www.gnu.org/software/smalltalk/gst-manual/gst_68.html#SEC238">http://www.gnu.org/software/smalltalk/gst-manual/gst_68.html#SEC238</A>.
In summary, a directive starts with <SAMP>‘%’</SAMP> and is followed by <SAMP>‘%’</SAMP>
or a nonzero digit (<SAMP>‘1’</SAMP> to <SAMP>‘9’</SAMP>).
</P>
<H3><A NAME="SEC261" HREF="gettext_toc.html#TOC261">15.3.10 Java Format Strings</A></H3>
<P>
Java format strings are described in the JDK documentation for class
<CODE>java.text.MessageFormat</CODE>,
<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/text/MessageFormat.html">http://java.sun.com/j2se/1.4/docs/api/java/text/MessageFormat.html</A>.
See also the ICU documentation
<A HREF="http://oss.software.ibm.com/icu/apiref/classMessageFormat.html">http://oss.software.ibm.com/icu/apiref/classMessageFormat.html</A>.
</P>
<H3><A NAME="SEC262" HREF="gettext_toc.html#TOC262">15.3.11 C# Format Strings</A></H3>
<P>
C# format strings are described in the .NET documentation for class
<CODE>System.String</CODE> and in
<A HREF="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpConFormattingOverview.asp">http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpConFormattingOverview.asp</A>.
</P>
<H3><A NAME="SEC263" HREF="gettext_toc.html#TOC263">15.3.12 awk Format Strings</A></H3>
<P>
awk format strings are described in the gawk documentation, section
Printf,
<A HREF="http://www.gnu.org/manual/gawk/html_node/Printf.html#Printf">http://www.gnu.org/manual/gawk/html_node/Printf.html#Printf</A>.
</P>
<H3><A NAME="SEC264" HREF="gettext_toc.html#TOC264">15.3.13 Object Pascal Format Strings</A></H3>
<P>
Object Pascal format strings are described in the documentation of the
Free Pascal runtime library, section Format,
<A HREF="http://www.freepascal.org/docs-html/rtl/sysutils/format.html">http://www.freepascal.org/docs-html/rtl/sysutils/format.html</A>.
</P>
<H3><A NAME="SEC265" HREF="gettext_toc.html#TOC265">15.3.14 YCP Format Strings</A></H3>
<P>
YCP sformat strings are described in the libycp documentation
<A HREF="file:/usr/share/doc/packages/libycp/YCP-builtins.html">file:/usr/share/doc/packages/libycp/YCP-builtins.html</A>.
In summary, a directive starts with <SAMP>‘%’</SAMP> and is followed by <SAMP>‘%’</SAMP>
or a nonzero digit (<SAMP>‘1’</SAMP> to <SAMP>‘9’</SAMP>).
</P>
<H3><A NAME="SEC266" HREF="gettext_toc.html#TOC266">15.3.15 Tcl Format Strings</A></H3>
<P>
Tcl format strings are described in the <TT>‘format.n’</TT> manual page,
<A HREF="http://www.scriptics.com/man/tcl8.3/TclCmd/format.htm">http://www.scriptics.com/man/tcl8.3/TclCmd/format.htm</A>.
</P>
<H3><A NAME="SEC267" HREF="gettext_toc.html#TOC267">15.3.16 Perl Format Strings</A></H3>
<P>
There are two kinds format strings in Perl: those acceptable to the
Perl built-in function <CODE>printf</CODE>, labelled as <SAMP>‘perl-format’</SAMP>,
and those acceptable to the <CODE>libintl-perl</CODE> function <CODE>__x</CODE>,
labelled as <SAMP>‘perl-brace-format’</SAMP>.
</P>
<P>
Perl <CODE>printf</CODE> format strings are described in the <CODE>sprintf</CODE>
section of <SAMP>‘man perlfunc’</SAMP>.
</P>
<P>
Perl brace format strings are described in the
<TT>‘Locale::TextDomain(3pm)’</TT> manual page of the CPAN package
libintl-perl. In brief, Perl format uses placeholders put between
braces (<SAMP>‘{’</SAMP> and <SAMP>‘}’</SAMP>). The placeholder must have the syntax
of simple identifiers.
</P>
<H3><A NAME="SEC268" HREF="gettext_toc.html#TOC268">15.3.17 PHP Format Strings</A></H3>
<P>
PHP format strings are described in the documentation of the PHP function
<CODE>sprintf</CODE>, in <TT>‘phpdoc/manual/function.sprintf.html’</TT> or
<A HREF="http://www.php.net/manual/en/function.sprintf.php">http://www.php.net/manual/en/function.sprintf.php</A>.
</P>
<H3><A NAME="SEC269" HREF="gettext_toc.html#TOC269">15.3.18 GCC internal Format Strings</A></H3>
<P>
These format strings are used inside the GCC sources. In such a format
string, a directive starts with <SAMP>‘%’</SAMP>, is optionally followed by a
size specifier <SAMP>‘l’</SAMP>, an optional flag <SAMP>‘+’</SAMP>, another optional flag
<SAMP>‘#’</SAMP>, and is finished by a specifier: <SAMP>‘%’</SAMP> denotes a literal
percent sign, <SAMP>‘c’</SAMP> denotes a character, <SAMP>‘s’</SAMP> denotes a string,
<SAMP>‘i’</SAMP> and <SAMP>‘d’</SAMP> denote an integer, <SAMP>‘o’</SAMP>, <SAMP>‘u’</SAMP>, <SAMP>‘x’</SAMP>
denote an unsigned integer, <SAMP>‘.*s’</SAMP> denotes a string preceded by a
width specification, <SAMP>‘H’</SAMP> denotes a <SAMP>‘location_t *’</SAMP> pointer,
<SAMP>‘D’</SAMP> denotes a general declaration, <SAMP>‘F’</SAMP> denotes a function
declaration, <SAMP>‘T’</SAMP> denotes a type, <SAMP>‘A’</SAMP> denotes a function argument,
<SAMP>‘C’</SAMP> denotes a tree code, <SAMP>‘E’</SAMP> denotes an expression, <SAMP>‘L’</SAMP>
denotes a programming language, <SAMP>‘O’</SAMP> denotes a binary operator,
<SAMP>‘P’</SAMP> denotes a function parameter, <SAMP>‘Q’</SAMP> denotes an assignment
operator, <SAMP>‘V’</SAMP> denotes a const/volatile qualifier.
</P>
<H3><A NAME="SEC270" HREF="gettext_toc.html#TOC270">15.3.19 GFC internal Format Strings</A></H3>
<P>
These format strings are used inside the GNU Fortran Compiler sources,
that is, the Fortran frontend in the GCC sources. In such a format
string, a directive starts with <SAMP>‘%’</SAMP> and is finished by a
specifier: <SAMP>‘%’</SAMP> denotes a literal percent sign, <SAMP>‘C’</SAMP> denotes the
current source location, <SAMP>‘L’</SAMP> denotes a source location, <SAMP>‘c’</SAMP>
denotes a character, <SAMP>‘s’</SAMP> denotes a string, <SAMP>‘i’</SAMP> and <SAMP>‘d’</SAMP>
denote an integer, <SAMP>‘u’</SAMP> denotes an unsigned integer. <SAMP>‘i’</SAMP>,
<SAMP>‘d’</SAMP>, and <SAMP>‘u’</SAMP> may be preceded by a size specifier <SAMP>‘l’</SAMP>.
</P>
<H3><A NAME="SEC271" HREF="gettext_toc.html#TOC271">15.3.20 Qt Format Strings</A></H3>
<P>
Qt format strings are described in the documentation of the QString class
<A HREF="file:/usr/lib/qt-4.3.0/doc/html/qstring.html">file:/usr/lib/qt-4.3.0/doc/html/qstring.html</A>.
In summary, a directive consists of a <SAMP>‘%’</SAMP> followed by a digit. The same
directive cannot occur more than once in a format string.
</P>
<H3><A NAME="SEC272" HREF="gettext_toc.html#TOC272">15.3.21 Qt Format Strings</A></H3>
<P>
Qt format strings are described in the documentation of the QObject::tr method
<A HREF="file:/usr/lib/qt-4.3.0/doc/html/qobject.html">file:/usr/lib/qt-4.3.0/doc/html/qobject.html</A>.
In summary, the only allowed directive is <SAMP>‘%n’</SAMP>.
</P>
<H3><A NAME="SEC273" HREF="gettext_toc.html#TOC273">15.3.22 KDE Format Strings</A></H3>
<P>
KDE 4 format strings are defined as follows:
A directive consists of a <SAMP>‘%’</SAMP> followed by a non-zero decimal number.
If a <SAMP>‘%n’</SAMP> occurs in a format strings, all of <SAMP>‘%1’</SAMP>, ..., <SAMP>‘%(n-1)’</SAMP>
must occur as well, except possibly one of them.
</P>
<H3><A NAME="SEC274" HREF="gettext_toc.html#TOC274">15.3.23 KUIT Format Strings</A></H3>
<P>
KUIT (KDE User Interface Text) is compatible with KDE 4 format strings,
while it also allows programmers to add semantic information to a format
string, through XML markup tags. For example, if the first format
directive in a string is a filename, programmers could indicate that
with a <SAMP>‘filename’</SAMP> tag, like <SAMP>‘<filename>%1</filename>’</SAMP>.
</P>
<P>
KUIT format strings are described in
<A HREF="http://api.kde.org/frameworks-api/frameworks5-apidocs/ki18n/html/prg_guide.html#kuit_markup">http://api.kde.org/frameworks-api/frameworks5-apidocs/ki18n/html/prg_guide.html#kuit_markup</A>.
</P>
<H3><A NAME="SEC275" HREF="gettext_toc.html#TOC275">15.3.24 Boost Format Strings</A></H3>
<P>
Boost format strings are described in the documentation of the
<CODE>boost::format</CODE> class, at
<A HREF="http://www.boost.org/libs/format/doc/format.html">http://www.boost.org/libs/format/doc/format.html</A>.
In summary, a directive has either the same syntax as in a C format string,
such as <SAMP>‘%1$+5d’</SAMP>, or may be surrounded by vertical bars, such as
<SAMP>‘%|1$+5d|’</SAMP> or <SAMP>‘%|1$+5|’</SAMP>, or consists of just an argument number
between percent signs, such as <SAMP>‘%1%’</SAMP>.
</P>
<H3><A NAME="SEC276" HREF="gettext_toc.html#TOC276">15.3.25 Lua Format Strings</A></H3>
<P>
Lua format strings are described in the Lua reference manual, section String Manipulation,
<A HREF="http://www.lua.org/manual/5.1/manual.html#pdf-string.format">http://www.lua.org/manual/5.1/manual.html#pdf-string.format</A>.
</P>
<H3><A NAME="SEC277" HREF="gettext_toc.html#TOC277">15.3.26 JavaScript Format Strings</A></H3>
<P>
Although JavaScript specification itself does not define any format
strings, many JavaScript implementations provide printf-like
functions. <CODE>xgettext</CODE> understands a set of common format strings
used in popular JavaScript implementations including Gjs, Seed, and
Node.JS. In such a format string, a directive starts with <SAMP>‘%’</SAMP>
and is finished by a specifier: <SAMP>‘%’</SAMP> denotes a literal percent
sign, <SAMP>‘c’</SAMP> denotes a character, <SAMP>‘s’</SAMP> denotes a string,
<SAMP>‘b’</SAMP>, <SAMP>‘d’</SAMP>, <SAMP>‘o’</SAMP>, <SAMP>‘x’</SAMP>, <SAMP>‘X’</SAMP> denote an integer,
<SAMP>‘f’</SAMP> denotes floating-point number, <SAMP>‘j’</SAMP> denotes a JSON
object.
</P>
<H2><A NAME="SEC278" HREF="gettext_toc.html#TOC278">15.4 The Maintainer's View</A></H2>
<P>
For the maintainer, the general procedure differs from the C language
case in two ways.
</P>
<UL>
<LI>
For those languages that don't use GNU gettext, the <TT>‘intl/’</TT> directory
is not needed and can be omitted. This means that the maintainer calls the
<CODE>gettextize</CODE> program without the <SAMP>‘--intl’</SAMP> option, and that he
invokes the <CODE>AM_GNU_GETTEXT</CODE> autoconf macro via
<SAMP>‘AM_GNU_GETTEXT([external])’</SAMP>.
<LI>
If only a single programming language is used, the <CODE>XGETTEXT_OPTIONS</CODE>
variable in <TT>‘po/Makevars’</TT> (see section <A HREF="gettext_13.html#SEC220">13.4.3 <TT>‘Makevars’</TT> in <TT>‘po/’</TT></A>) should be adjusted to
match the <CODE>xgettext</CODE> options for that particular programming language.
If the package uses more than one programming language with <CODE>gettext</CODE>
support, it becomes necessary to change the POT file construction rule
in <TT>‘po/Makefile.in.in’</TT>. It is recommended to make one <CODE>xgettext</CODE>
invocation per programming language, each with the options appropriate for
that language, and to combine the resulting files using <CODE>msgcat</CODE>.
</UL>
<H2><A NAME="SEC279" HREF="gettext_toc.html#TOC279">15.5 Individual Programming Languages</A></H2>
<H3><A NAME="SEC280" HREF="gettext_toc.html#TOC280">15.5.1 C, C++, Objective C</A></H3>
<P>
<A NAME="IDX1221"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
gcc, gpp, gobjc, glibc, gettext
<DT>File extension
<DD>
For C: <CODE>c</CODE>, <CODE>h</CODE>.
<BR>For C++: <CODE>C</CODE>, <CODE>c++</CODE>, <CODE>cc</CODE>, <CODE>cxx</CODE>, <CODE>cpp</CODE>, <CODE>hpp</CODE>.
<BR>For Objective C: <CODE>m</CODE>.
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>_("abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>, <CODE>dgettext</CODE>, <CODE>dcgettext</CODE>, <CODE>ngettext</CODE>,
<CODE>dngettext</CODE>, <CODE>dcngettext</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE> function
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function
<DT>setlocale
<DD>
Programmer must call <CODE>setlocale (LC_ALL, "")</CODE>
<DT>Prerequisite
<DD>
<CODE>#include <libintl.h></CODE>
<BR><CODE>#include <locale.h></CODE>
<BR><CODE>#define _(string) gettext (string)</CODE>
<DT>Use or emulate GNU gettext
<DD>
Use
<DT>Extractor
<DD>
<CODE>xgettext -k_</CODE>
<DT>Formatting with positions
<DD>
<CODE>fprintf "%2$d %1$d"</CODE>
<BR>In C++: <CODE>autosprintf "%2$d %1$d"</CODE>
(see section ‘Introduction’ in <CITE>GNU autosprintf</CITE>)
<DT>Portability
<DD>
autoconf (gettext.m4) and #if ENABLE_NLS
<DT>po-mode marking
<DD>
yes
</DL>
<P>
The following examples are available in the <TT>‘examples’</TT> directory:
<CODE>hello-c</CODE>, <CODE>hello-c-gnome</CODE>, <CODE>hello-c++</CODE>, <CODE>hello-c++-qt</CODE>,
<CODE>hello-c++-kde</CODE>, <CODE>hello-c++-gnome</CODE>, <CODE>hello-c++-wxwidgets</CODE>,
<CODE>hello-objc</CODE>, <CODE>hello-objc-gnustep</CODE>, <CODE>hello-objc-gnome</CODE>.
</P>
<H3><A NAME="SEC281" HREF="gettext_toc.html#TOC281">15.5.2 sh - Shell Script</A></H3>
<P>
<A NAME="IDX1222"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
bash, gettext
<DT>File extension
<DD>
<CODE>sh</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>, <CODE>'abc'</CODE>, <CODE>abc</CODE>
<DT>gettext shorthand
<DD>
<CODE>"`gettext \"abc\"`"</CODE>
<DT>gettext/ngettext functions
<DD>
<A NAME="IDX1223"></A>
<A NAME="IDX1224"></A>
<CODE>gettext</CODE>, <CODE>ngettext</CODE> programs
<BR><CODE>eval_gettext</CODE>, <CODE>eval_ngettext</CODE> shell functions
<DT>textdomain
<DD>
<A NAME="IDX1225"></A>
environment variable <CODE>TEXTDOMAIN</CODE>
<DT>bindtextdomain
<DD>
<A NAME="IDX1226"></A>
environment variable <CODE>TEXTDOMAINDIR</CODE>
<DT>setlocale
<DD>
automatic
<DT>Prerequisite
<DD>
<CODE>. gettext.sh</CODE>
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
---
<DT>Portability
<DD>
fully portable
<DT>po-mode marking
<DD>
---
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-sh</CODE>.
</P>
<H4><A NAME="SEC282" HREF="gettext_toc.html#TOC282">15.5.2.1 Preparing Shell Scripts for Internationalization</A></H4>
<P>
<A NAME="IDX1227"></A>
</P>
<P>
Preparing a shell script for internationalization is conceptually similar
to the steps described in section <A HREF="gettext_4.html#SEC16">4 Preparing Program Sources</A>. The concrete steps for shell
scripts are as follows.
</P>
<OL>
<LI>
Insert the line
<PRE>
. gettext.sh
</PRE>
near the top of the script. <CODE>gettext.sh</CODE> is a shell function library
that provides the functions
<CODE>eval_gettext</CODE> (see section <A HREF="gettext_15.html#SEC287">15.5.2.6 Invoking the <CODE>eval_gettext</CODE> function</A>) and
<CODE>eval_ngettext</CODE> (see section <A HREF="gettext_15.html#SEC288">15.5.2.7 Invoking the <CODE>eval_ngettext</CODE> function</A>).
You have to ensure that <CODE>gettext.sh</CODE> can be found in the <CODE>PATH</CODE>.
<LI>
Set and export the <CODE>TEXTDOMAIN</CODE> and <CODE>TEXTDOMAINDIR</CODE> environment
variables. Usually <CODE>TEXTDOMAIN</CODE> is the package or program name, and
<CODE>TEXTDOMAINDIR</CODE> is the absolute pathname corresponding to
<CODE>$prefix/share/locale</CODE>, where <CODE>$prefix</CODE> is the installation location.
<PRE>
TEXTDOMAIN=@PACKAGE@
export TEXTDOMAIN
TEXTDOMAINDIR=@LOCALEDIR@
export TEXTDOMAINDIR
</PRE>
<LI>
Prepare the strings for translation, as described in section <A HREF="gettext_4.html#SEC19">4.3 Preparing Translatable Strings</A>.
<LI>
Simplify translatable strings so that they don't contain command substitution
(<CODE>"`...`"</CODE> or <CODE>"$(...)"</CODE>), variable access with defaulting (like
<CODE>${<VAR>variable</VAR>-<VAR>default</VAR>}</CODE>), access to positional arguments
(like <CODE>$0</CODE>, <CODE>$1</CODE>, ...) or highly volatile shell variables (like
<CODE>$?</CODE>). This can always be done through simple local code restructuring.
For example,
<PRE>
echo "Usage: $0 [OPTION] FILE..."
</PRE>
becomes
<PRE>
program_name=$0
echo "Usage: $program_name [OPTION] FILE..."
</PRE>
Similarly,
<PRE>
echo "Remaining files: `ls | wc -l`"
</PRE>
becomes
<PRE>
filecount="`ls | wc -l`"
echo "Remaining files: $filecount"
</PRE>
<LI>
For each translatable string, change the output command <SAMP>‘echo’</SAMP> or
<SAMP>‘$echo’</SAMP> to <SAMP>‘gettext’</SAMP> (if the string contains no references to
shell variables) or to <SAMP>‘eval_gettext’</SAMP> (if it refers to shell variables),
followed by a no-argument <SAMP>‘echo’</SAMP> command (to account for the terminating
newline). Similarly, for cases with plural handling, replace a conditional
<SAMP>‘echo’</SAMP> command with an invocation of <SAMP>‘ngettext’</SAMP> or
<SAMP>‘eval_ngettext’</SAMP>, followed by a no-argument <SAMP>‘echo’</SAMP> command.
When doing this, you also need to add an extra backslash before the dollar
sign in references to shell variables, so that the <SAMP>‘eval_gettext’</SAMP>
function receives the translatable string before the variable values are
substituted into it. For example,
<PRE>
echo "Remaining files: $filecount"
</PRE>
becomes
<PRE>
eval_gettext "Remaining files: \$filecount"; echo
</PRE>
If the output command is not <SAMP>‘echo’</SAMP>, you can make it use <SAMP>‘echo’</SAMP>
nevertheless, through the use of backquotes. However, note that inside
backquotes, backslashes must be doubled to be effective (because the
backquoting eats one level of backslashes). For example, assuming that
<SAMP>‘error’</SAMP> is a shell function that signals an error,
<PRE>
error "file not found: $filename"
</PRE>
is first transformed into
<PRE>
error "`echo \"file not found: \$filename\"`"
</PRE>
which then becomes
<PRE>
error "`eval_gettext \"file not found: \\\$filename\"`"
</PRE>
</OL>
<H4><A NAME="SEC283" HREF="gettext_toc.html#TOC283">15.5.2.2 Contents of <CODE>gettext.sh</CODE></A></H4>
<P>
<CODE>gettext.sh</CODE>, contained in the run-time package of GNU gettext, provides
the following:
</P>
<UL>
<LI>$echo
The variable <CODE>echo</CODE> is set to a command that outputs its first argument
and a newline, without interpreting backslashes in the argument string.
<LI>eval_gettext
See section <A HREF="gettext_15.html#SEC287">15.5.2.6 Invoking the <CODE>eval_gettext</CODE> function</A>.
<LI>eval_ngettext
See section <A HREF="gettext_15.html#SEC288">15.5.2.7 Invoking the <CODE>eval_ngettext</CODE> function</A>.
</UL>
<H4><A NAME="SEC284" HREF="gettext_toc.html#TOC284">15.5.2.3 Invoking the <CODE>gettext</CODE> program</A></H4>
<P>
<A NAME="IDX1228"></A>
<A NAME="IDX1229"></A>
<PRE>
gettext [<VAR>option</VAR>] [[<VAR>textdomain</VAR>] <VAR>msgid</VAR>]
gettext [<VAR>option</VAR>] -s [<VAR>msgid</VAR>]...
</PRE>
<P>
<A NAME="IDX1230"></A>
The <CODE>gettext</CODE> program displays the native language translation of a
textual message.
</P>
<P>
<STRONG>Arguments</STRONG>
</P>
<DL COMPACT>
<DT><SAMP>‘-d <VAR>textdomain</VAR>’</SAMP>
<DD>
<DT><SAMP>‘--domain=<VAR>textdomain</VAR>’</SAMP>
<DD>
<A NAME="IDX1231"></A>
<A NAME="IDX1232"></A>
Retrieve translated messages from <VAR>textdomain</VAR>. Usually a <VAR>textdomain</VAR>
corresponds to a package, a program, or a module of a program.
<DT><SAMP>‘-e’</SAMP>
<DD>
<A NAME="IDX1233"></A>
Enable expansion of some escape sequences. This option is for compatibility
with the <SAMP>‘echo’</SAMP> program or shell built-in. The escape sequences
<SAMP>‘\a’</SAMP>, <SAMP>‘\b’</SAMP>, <SAMP>‘\c’</SAMP>, <SAMP>‘\f’</SAMP>, <SAMP>‘\n’</SAMP>, <SAMP>‘\r’</SAMP>, <SAMP>‘\t’</SAMP>,
<SAMP>‘\v’</SAMP>, <SAMP>‘\\’</SAMP>, and <SAMP>‘\’</SAMP> followed by one to three octal digits, are
interpreted like the System V <SAMP>‘echo’</SAMP> program did.
<DT><SAMP>‘-E’</SAMP>
<DD>
<A NAME="IDX1234"></A>
This option is only for compatibility with the <SAMP>‘echo’</SAMP> program or shell
built-in. It has no effect.
<DT><SAMP>‘-h’</SAMP>
<DD>
<DT><SAMP>‘--help’</SAMP>
<DD>
<A NAME="IDX1235"></A>
<A NAME="IDX1236"></A>
Display this help and exit.
<DT><SAMP>‘-n’</SAMP>
<DD>
<A NAME="IDX1237"></A>
Suppress trailing newline. By default, <CODE>gettext</CODE> adds a newline to
the output.
<DT><SAMP>‘-V’</SAMP>
<DD>
<DT><SAMP>‘--version’</SAMP>
<DD>
<A NAME="IDX1238"></A>
<A NAME="IDX1239"></A>
Output version information and exit.
<DT><SAMP>‘[<VAR>textdomain</VAR>] <VAR>msgid</VAR>’</SAMP>
<DD>
Retrieve translated message corresponding to <VAR>msgid</VAR> from <VAR>textdomain</VAR>.
</DL>
<P>
If the <VAR>textdomain</VAR> parameter is not given, the domain is determined from
the environment variable <CODE>TEXTDOMAIN</CODE>. If the message catalog is not
found in the regular directory, another location can be specified with the
environment variable <CODE>TEXTDOMAINDIR</CODE>.
</P>
<P>
When used with the <CODE>-s</CODE> option the program behaves like the <SAMP>‘echo’</SAMP>
command. But it does not simply copy its arguments to stdout. Instead those
messages found in the selected catalog are translated.
</P>
<P>
Note: <CODE>xgettext</CODE> supports only the one-argument form of the
<CODE>gettext</CODE> invocation, where no options are present and the
<VAR>textdomain</VAR> is implicit, from the environment.
</P>
<H4><A NAME="SEC285" HREF="gettext_toc.html#TOC285">15.5.2.4 Invoking the <CODE>ngettext</CODE> program</A></H4>
<P>
<A NAME="IDX1240"></A>
<A NAME="IDX1241"></A>
<PRE>
ngettext [<VAR>option</VAR>] [<VAR>textdomain</VAR>] <VAR>msgid</VAR> <VAR>msgid-plural</VAR> <VAR>count</VAR>
</PRE>
<P>
<A NAME="IDX1242"></A>
The <CODE>ngettext</CODE> program displays the native language translation of a
textual message whose grammatical form depends on a number.
</P>
<P>
<STRONG>Arguments</STRONG>
</P>
<DL COMPACT>
<DT><SAMP>‘-d <VAR>textdomain</VAR>’</SAMP>
<DD>
<DT><SAMP>‘--domain=<VAR>textdomain</VAR>’</SAMP>
<DD>
<A NAME="IDX1243"></A>
<A NAME="IDX1244"></A>
Retrieve translated messages from <VAR>textdomain</VAR>. Usually a <VAR>textdomain</VAR>
corresponds to a package, a program, or a module of a program.
<DT><SAMP>‘-e’</SAMP>
<DD>
<A NAME="IDX1245"></A>
Enable expansion of some escape sequences. This option is for compatibility
with the <SAMP>‘gettext’</SAMP> program. The escape sequences
<SAMP>‘\a’</SAMP>, <SAMP>‘\b’</SAMP>, <SAMP>‘\c’</SAMP>, <SAMP>‘\f’</SAMP>, <SAMP>‘\n’</SAMP>, <SAMP>‘\r’</SAMP>, <SAMP>‘\t’</SAMP>,
<SAMP>‘\v’</SAMP>, <SAMP>‘\\’</SAMP>, and <SAMP>‘\’</SAMP> followed by one to three octal digits, are
interpreted like the System V <SAMP>‘echo’</SAMP> program did.
<DT><SAMP>‘-E’</SAMP>
<DD>
<A NAME="IDX1246"></A>
This option is only for compatibility with the <SAMP>‘gettext’</SAMP> program. It has
no effect.
<DT><SAMP>‘-h’</SAMP>
<DD>
<DT><SAMP>‘--help’</SAMP>
<DD>
<A NAME="IDX1247"></A>
<A NAME="IDX1248"></A>
Display this help and exit.
<DT><SAMP>‘-V’</SAMP>
<DD>
<DT><SAMP>‘--version’</SAMP>
<DD>
<A NAME="IDX1249"></A>
<A NAME="IDX1250"></A>
Output version information and exit.
<DT><SAMP>‘<VAR>textdomain</VAR>’</SAMP>
<DD>
Retrieve translated message from <VAR>textdomain</VAR>.
<DT><SAMP>‘<VAR>msgid</VAR> <VAR>msgid-plural</VAR>’</SAMP>
<DD>
Translate <VAR>msgid</VAR> (English singular) / <VAR>msgid-plural</VAR> (English plural).
<DT><SAMP>‘<VAR>count</VAR>’</SAMP>
<DD>
Choose singular/plural form based on this value.
</DL>
<P>
If the <VAR>textdomain</VAR> parameter is not given, the domain is determined from
the environment variable <CODE>TEXTDOMAIN</CODE>. If the message catalog is not
found in the regular directory, another location can be specified with the
environment variable <CODE>TEXTDOMAINDIR</CODE>.
</P>
<P>
Note: <CODE>xgettext</CODE> supports only the three-arguments form of the
<CODE>ngettext</CODE> invocation, where no options are present and the
<VAR>textdomain</VAR> is implicit, from the environment.
</P>
<H4><A NAME="SEC286" HREF="gettext_toc.html#TOC286">15.5.2.5 Invoking the <CODE>envsubst</CODE> program</A></H4>
<P>
<A NAME="IDX1251"></A>
<A NAME="IDX1252"></A>
<PRE>
envsubst [<VAR>option</VAR>] [<VAR>shell-format</VAR>]
</PRE>
<P>
<A NAME="IDX1253"></A>
<A NAME="IDX1254"></A>
<A NAME="IDX1255"></A>
The <CODE>envsubst</CODE> program substitutes the values of environment variables.
</P>
<P>
<STRONG>Operation mode</STRONG>
</P>
<DL COMPACT>
<DT><SAMP>‘-v’</SAMP>
<DD>
<DT><SAMP>‘--variables’</SAMP>
<DD>
<A NAME="IDX1256"></A>
<A NAME="IDX1257"></A>
Output the variables occurring in <VAR>shell-format</VAR>.
</DL>
<P>
<STRONG>Informative output</STRONG>
</P>
<DL COMPACT>
<DT><SAMP>‘-h’</SAMP>
<DD>
<DT><SAMP>‘--help’</SAMP>
<DD>
<A NAME="IDX1258"></A>
<A NAME="IDX1259"></A>
Display this help and exit.
<DT><SAMP>‘-V’</SAMP>
<DD>
<DT><SAMP>‘--version’</SAMP>
<DD>
<A NAME="IDX1260"></A>
<A NAME="IDX1261"></A>
Output version information and exit.
</DL>
<P>
In normal operation mode, standard input is copied to standard output,
with references to environment variables of the form <CODE>$VARIABLE</CODE> or
<CODE>${VARIABLE}</CODE> being replaced with the corresponding values. If a
<VAR>shell-format</VAR> is given, only those environment variables that are
referenced in <VAR>shell-format</VAR> are substituted; otherwise all environment
variables references occurring in standard input are substituted.
</P>
<P>
These substitutions are a subset of the substitutions that a shell performs
on unquoted and double-quoted strings. Other kinds of substitutions done
by a shell, such as <CODE>${<VAR>variable</VAR>-<VAR>default</VAR>}</CODE> or
<CODE>$(<VAR>command-list</VAR>)</CODE> or <CODE>`<VAR>command-list</VAR>`</CODE>, are not performed
by the <CODE>envsubst</CODE> program, due to security reasons.
</P>
<P>
When <CODE>--variables</CODE> is used, standard input is ignored, and the output
consists of the environment variables that are referenced in
<VAR>shell-format</VAR>, one per line.
</P>
<H4><A NAME="SEC287" HREF="gettext_toc.html#TOC287">15.5.2.6 Invoking the <CODE>eval_gettext</CODE> function</A></H4>
<P>
<A NAME="IDX1262"></A>
<PRE>
eval_gettext <VAR>msgid</VAR>
</PRE>
<P>
<A NAME="IDX1263"></A>
This function outputs the native language translation of a textual message,
performing dollar-substitution on the result. Note that only shell variables
mentioned in <VAR>msgid</VAR> will be dollar-substituted in the result.
</P>
<H4><A NAME="SEC288" HREF="gettext_toc.html#TOC288">15.5.2.7 Invoking the <CODE>eval_ngettext</CODE> function</A></H4>
<P>
<A NAME="IDX1264"></A>
<PRE>
eval_ngettext <VAR>msgid</VAR> <VAR>msgid-plural</VAR> <VAR>count</VAR>
</PRE>
<P>
<A NAME="IDX1265"></A>
This function outputs the native language translation of a textual message
whose grammatical form depends on a number, performing dollar-substitution
on the result. Note that only shell variables mentioned in <VAR>msgid</VAR> or
<VAR>msgid-plural</VAR> will be dollar-substituted in the result.
</P>
<H3><A NAME="SEC289" HREF="gettext_toc.html#TOC289">15.5.3 bash - Bourne-Again Shell Script</A></H3>
<P>
<A NAME="IDX1266"></A>
</P>
<P>
GNU <CODE>bash</CODE> 2.0 or newer has a special shorthand for translating a
string and substituting variable values in it: <CODE>$"msgid"</CODE>. But
the use of this construct is <STRONG>discouraged</STRONG>, due to the security
holes it opens and due to its portability problems.
</P>
<P>
The security holes of <CODE>$"..."</CODE> come from the fact that after looking up
the translation of the string, <CODE>bash</CODE> processes it like it processes
any double-quoted string: dollar and backquote processing, like <SAMP>‘eval’</SAMP>
does.
</P>
<OL>
<LI>
In a locale whose encoding is one of BIG5, BIG5-HKSCS, GBK, GB18030, SHIFT_JIS,
JOHAB, some double-byte characters have a second byte whose value is
<CODE>0x60</CODE>. For example, the byte sequence <CODE>\xe0\x60</CODE> is a single
character in these locales. Many versions of <CODE>bash</CODE> (all versions
up to bash-2.05, and newer versions on platforms without <CODE>mbsrtowcs()</CODE>
function) don't know about character boundaries and see a backquote character
where there is only a particular Chinese character. Thus it can start
executing part of the translation as a command list. This situation can occur
even without the translator being aware of it: if the translator provides
translations in the UTF-8 encoding, it is the <CODE>gettext()</CODE> function which
will, during its conversion from the translator's encoding to the user's
locale's encoding, produce the dangerous <CODE>\x60</CODE> bytes.
<LI>
A translator could - voluntarily or inadvertently - use backquotes
<CODE>"`...`"</CODE> or dollar-parentheses <CODE>"$(...)"</CODE> in her translations.
The enclosed strings would be executed as command lists by the shell.
</OL>
<P>
The portability problem is that <CODE>bash</CODE> must be built with
internationalization support; this is normally not the case on systems
that don't have the <CODE>gettext()</CODE> function in libc.
</P>
<H3><A NAME="SEC290" HREF="gettext_toc.html#TOC290">15.5.4 Python</A></H3>
<P>
<A NAME="IDX1267"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
python
<DT>File extension
<DD>
<CODE>py</CODE>
<DT>String syntax
<DD>
<CODE>'abc'</CODE>, <CODE>u'abc'</CODE>, <CODE>r'abc'</CODE>, <CODE>ur'abc'</CODE>,
<BR><CODE>"abc"</CODE>, <CODE>u"abc"</CODE>, <CODE>r"abc"</CODE>, <CODE>ur"abc"</CODE>,
<BR><CODE>”'abc”'</CODE>, <CODE>u”'abc”'</CODE>, <CODE>r”'abc”'</CODE>, <CODE>ur”'abc”'</CODE>,
<BR><CODE>"""abc"""</CODE>, <CODE>u"""abc"""</CODE>, <CODE>r"""abc"""</CODE>, <CODE>ur"""abc"""</CODE>
<DT>gettext shorthand
<DD>
<CODE>_('abc')</CODE> etc.
<DT>gettext/ngettext functions
<DD>
<CODE>gettext.gettext</CODE>, <CODE>gettext.dgettext</CODE>,
<CODE>gettext.ngettext</CODE>, <CODE>gettext.dngettext</CODE>,
also <CODE>ugettext</CODE>, <CODE>ungettext</CODE>
<DT>textdomain
<DD>
<CODE>gettext.textdomain</CODE> function, or
<CODE>gettext.install(<VAR>domain</VAR>)</CODE> function
<DT>bindtextdomain
<DD>
<CODE>gettext.bindtextdomain</CODE> function, or
<CODE>gettext.install(<VAR>domain</VAR>,<VAR>localedir</VAR>)</CODE> function
<DT>setlocale
<DD>
not used by the gettext emulation
<DT>Prerequisite
<DD>
<CODE>import gettext</CODE>
<DT>Use or emulate GNU gettext
<DD>
emulate
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
<CODE>'...%(ident)d...' % { 'ident': value }</CODE>
<DT>Portability
<DD>
fully portable
<DT>po-mode marking
<DD>
---
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-python</CODE>.
</P>
<P>
A note about format strings: Python supports format strings with unnamed
arguments, such as <CODE>'...%d...'</CODE>, and format strings with named arguments,
such as <CODE>'...%(ident)d...'</CODE>. The latter are preferable for
internationalized programs, for two reasons:
</P>
<UL>
<LI>
When a format string takes more than one argument, the translator can provide
a translation that uses the arguments in a different order, if the format
string uses named arguments. For example, the translator can reformulate
<PRE>
"'%(volume)s' has only %(freespace)d bytes free."
</PRE>
to
<PRE>
"Only %(freespace)d bytes free on '%(volume)s'."
</PRE>
Additionally, the identifiers also provide some context to the translator.
<LI>
In the context of plural forms, the format string used for the singular form
does not use the numeric argument in many languages. Even in English, one
prefers to write <CODE>"one hour"</CODE> instead of <CODE>"1 hour"</CODE>. Omitting
individual arguments from format strings like this is only possible with
the named argument syntax. (With unnamed arguments, Python -- unlike C --
verifies that the format string uses all supplied arguments.)
</UL>
<H3><A NAME="SEC291" HREF="gettext_toc.html#TOC291">15.5.5 GNU clisp - Common Lisp</A></H3>
<P>
<A NAME="IDX1268"></A>
<A NAME="IDX1269"></A>
<A NAME="IDX1270"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
clisp 2.28 or newer
<DT>File extension
<DD>
<CODE>lisp</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>(_ "abc")</CODE>, <CODE>(ENGLISH "abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>i18n:gettext</CODE>, <CODE>i18n:ngettext</CODE>
<DT>textdomain
<DD>
<CODE>i18n:textdomain</CODE>
<DT>bindtextdomain
<DD>
<CODE>i18n:textdomaindir</CODE>
<DT>setlocale
<DD>
automatic
<DT>Prerequisite
<DD>
---
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>xgettext -k_ -kENGLISH</CODE>
<DT>Formatting with positions
<DD>
<CODE>format "~1@*~D ~0@*~D"</CODE>
<DT>Portability
<DD>
On platforms without gettext, no translation.
<DT>po-mode marking
<DD>
---
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-clisp</CODE>.
</P>
<H3><A NAME="SEC292" HREF="gettext_toc.html#TOC292">15.5.6 GNU clisp C sources</A></H3>
<P>
<A NAME="IDX1271"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
clisp
<DT>File extension
<DD>
<CODE>d</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>ENGLISH ? "abc" : ""</CODE>
<BR><CODE>GETTEXT("abc")</CODE>
<BR><CODE>GETTEXTL("abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>clgettext</CODE>, <CODE>clgettextl</CODE>
<DT>textdomain
<DD>
---
<DT>bindtextdomain
<DD>
---
<DT>setlocale
<DD>
automatic
<DT>Prerequisite
<DD>
<CODE>#include "lispbibl.c"</CODE>
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>clisp-xgettext</CODE>
<DT>Formatting with positions
<DD>
<CODE>fprintf "%2$d %1$d"</CODE>
<DT>Portability
<DD>
On platforms without gettext, no translation.
<DT>po-mode marking
<DD>
---
</DL>
<H3><A NAME="SEC293" HREF="gettext_toc.html#TOC293">15.5.7 Emacs Lisp</A></H3>
<P>
<A NAME="IDX1272"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
emacs, xemacs
<DT>File extension
<DD>
<CODE>el</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>(_"abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>, <CODE>dgettext</CODE> (xemacs only)
<DT>textdomain
<DD>
<CODE>domain</CODE> special form (xemacs only)
<DT>bindtextdomain
<DD>
<CODE>bind-text-domain</CODE> function (xemacs only)
<DT>setlocale
<DD>
automatic
<DT>Prerequisite
<DD>
---
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
<CODE>format "%2$d %1$d"</CODE>
<DT>Portability
<DD>
Only XEmacs. Without <CODE>I18N3</CODE> defined at build time, no translation.
<DT>po-mode marking
<DD>
---
</DL>
<H3><A NAME="SEC294" HREF="gettext_toc.html#TOC294">15.5.8 librep</A></H3>
<P>
<A NAME="IDX1273"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
librep 0.15.3 or newer
<DT>File extension
<DD>
<CODE>jl</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>(_"abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE> function
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function
<DT>setlocale
<DD>
---
<DT>Prerequisite
<DD>
<CODE>(require 'rep.i18n.gettext)</CODE>
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
<CODE>format "%2$d %1$d"</CODE>
<DT>Portability
<DD>
On platforms without gettext, no translation.
<DT>po-mode marking
<DD>
---
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-librep</CODE>.
</P>
<H3><A NAME="SEC295" HREF="gettext_toc.html#TOC295">15.5.9 GNU guile - Scheme</A></H3>
<P>
<A NAME="IDX1274"></A>
<A NAME="IDX1275"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
guile
<DT>File extension
<DD>
<CODE>scm</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>(_ "abc")</CODE>, <CODE>_"abc"</CODE> (GIMP script-fu extension)
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>, <CODE>ngettext</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE>
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE>
<DT>setlocale
<DD>
<CODE>(catch #t (lambda () (setlocale LC_ALL "")) (lambda args #f))</CODE>
<DT>Prerequisite
<DD>
<CODE>(use-modules (ice-9 format))</CODE>
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>xgettext -k_</CODE>
<DT>Formatting with positions
<DD>
---
<DT>Portability
<DD>
On platforms without gettext, no translation.
<DT>po-mode marking
<DD>
---
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-guile</CODE>.
</P>
<H3><A NAME="SEC296" HREF="gettext_toc.html#TOC296">15.5.10 GNU Smalltalk</A></H3>
<P>
<A NAME="IDX1276"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
smalltalk
<DT>File extension
<DD>
<CODE>st</CODE>
<DT>String syntax
<DD>
<CODE>'abc'</CODE>
<DT>gettext shorthand
<DD>
<CODE>NLS ? 'abc'</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>LcMessagesDomain>>#at:</CODE>, <CODE>LcMessagesDomain>>#at:plural:with:</CODE>
<DT>textdomain
<DD>
<CODE>LcMessages>>#domain:localeDirectory:</CODE> (returns a <CODE>LcMessagesDomain</CODE>
object).<BR>
Example: <CODE>I18N Locale default messages domain: 'gettext' localeDirectory: /usr/local/share/locale'</CODE>
<DT>bindtextdomain
<DD>
<CODE>LcMessages>>#domain:localeDirectory:</CODE>, see above.
<DT>setlocale
<DD>
Automatic if you use <CODE>I18N Locale default</CODE>.
<DT>Prerequisite
<DD>
<CODE>PackageLoader fileInPackage: 'I18N'!</CODE>
<DT>Use or emulate GNU gettext
<DD>
emulate
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
<CODE>'%1 %2' bindWith: 'Hello' with: 'world'</CODE>
<DT>Portability
<DD>
fully portable
<DT>po-mode marking
<DD>
---
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory:
<CODE>hello-smalltalk</CODE>.
</P>
<H3><A NAME="SEC297" HREF="gettext_toc.html#TOC297">15.5.11 Java</A></H3>
<P>
<A NAME="IDX1277"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
java, java2
<DT>File extension
<DD>
<CODE>java</CODE>
<DT>String syntax
<DD>
"abc"
<DT>gettext shorthand
<DD>
_("abc")
<DT>gettext/ngettext functions
<DD>
<CODE>GettextResource.gettext</CODE>, <CODE>GettextResource.ngettext</CODE>,
<CODE>GettextResource.pgettext</CODE>, <CODE>GettextResource.npgettext</CODE>
<DT>textdomain
<DD>
---, use <CODE>ResourceBundle.getResource</CODE> instead
<DT>bindtextdomain
<DD>
---, use CLASSPATH instead
<DT>setlocale
<DD>
automatic
<DT>Prerequisite
<DD>
---
<DT>Use or emulate GNU gettext
<DD>
---, uses a Java specific message catalog format
<DT>Extractor
<DD>
<CODE>xgettext -k_</CODE>
<DT>Formatting with positions
<DD>
<CODE>MessageFormat.format "{1,number} {0,number}"</CODE>
<DT>Portability
<DD>
fully portable
<DT>po-mode marking
<DD>
---
</DL>
<P>
Before marking strings as internationalizable, uses of the string
concatenation operator need to be converted to <CODE>MessageFormat</CODE>
applications. For example, <CODE>"file "+filename+" not found"</CODE> becomes
<CODE>MessageFormat.format("file {0} not found", new Object[] { filename })</CODE>.
Only after this is done, can the strings be marked and extracted.
</P>
<P>
GNU gettext uses the native Java internationalization mechanism, namely
<CODE>ResourceBundle</CODE>s. There are two formats of <CODE>ResourceBundle</CODE>s:
<CODE>.properties</CODE> files and <CODE>.class</CODE> files. The <CODE>.properties</CODE>
format is a text file which the translators can directly edit, like PO
files, but which doesn't support plural forms. Whereas the <CODE>.class</CODE>
format is compiled from <CODE>.java</CODE> source code and can support plural
forms (provided it is accessed through an appropriate API, see below).
</P>
<P>
To convert a PO file to a <CODE>.properties</CODE> file, the <CODE>msgcat</CODE>
program can be used with the option <CODE>--properties-output</CODE>. To convert
a <CODE>.properties</CODE> file back to a PO file, the <CODE>msgcat</CODE> program
can be used with the option <CODE>--properties-input</CODE>. All the tools
that manipulate PO files can work with <CODE>.properties</CODE> files as well,
if given the <CODE>--properties-input</CODE> and/or <CODE>--properties-output</CODE>
option.
</P>
<P>
To convert a PO file to a ResourceBundle class, the <CODE>msgfmt</CODE> program
can be used with the option <CODE>--java</CODE> or <CODE>--java2</CODE>. To convert a
ResourceBundle back to a PO file, the <CODE>msgunfmt</CODE> program can be used
with the option <CODE>--java</CODE>.
</P>
<P>
Two different programmatic APIs can be used to access ResourceBundles.
Note that both APIs work with all kinds of ResourceBundles, whether
GNU gettext generated classes, or other <CODE>.class</CODE> or <CODE>.properties</CODE>
files.
</P>
<OL>
<LI>
The <CODE>java.util.ResourceBundle</CODE> API.
In particular, its <CODE>getString</CODE> function returns a string translation.
Note that a missing translation yields a <CODE>MissingResourceException</CODE>.
This has the advantage of being the standard API. And it does not require
any additional libraries, only the <CODE>msgcat</CODE> generated <CODE>.properties</CODE>
files or the <CODE>msgfmt</CODE> generated <CODE>.class</CODE> files. But it cannot do
plural handling, even if the resource was generated by <CODE>msgfmt</CODE> from
a PO file with plural handling.
<LI>
The <CODE>gnu.gettext.GettextResource</CODE> API.
Reference documentation in Javadoc 1.1 style format is in the
<A HREF="javadoc2/index.html">javadoc2 directory</A>.
Its <CODE>gettext</CODE> function returns a string translation. Note that when
a translation is missing, the <VAR>msgid</VAR> argument is returned unchanged.
This has the advantage of having the <CODE>ngettext</CODE> function for plural
handling and the <CODE>pgettext</CODE> and <CODE>npgettext</CODE> for strings constraint
to a particular context.
<A NAME="IDX1278"></A>
To use this API, one needs the <CODE>libintl.jar</CODE> file which is part of
the GNU gettext package and distributed under the LGPL.
</OL>
<P>
Four examples, using the second API, are available in the <TT>‘examples’</TT>
directory: <CODE>hello-java</CODE>, <CODE>hello-java-awt</CODE>, <CODE>hello-java-swing</CODE>,
<CODE>hello-java-qtjambi</CODE>.
</P>
<P>
Now, to make use of the API and define a shorthand for <SAMP>‘getString’</SAMP>,
there are three idioms that you can choose from:
</P>
<UL>
<LI>
(This one assumes Java 1.5 or newer.)
In a unique class of your project, say <SAMP>‘Util’</SAMP>, define a static variable
holding the <CODE>ResourceBundle</CODE> instance and the shorthand:
<PRE>
private static ResourceBundle myResources =
ResourceBundle.getBundle("domain-name");
public static String _(String s) {
return myResources.getString(s);
}
</PRE>
All classes containing internationalized strings then contain
<PRE>
import static Util._;
</PRE>
and the shorthand is used like this:
<PRE>
System.out.println(_("Operation completed."));
</PRE>
<LI>
In a unique class of your project, say <SAMP>‘Util’</SAMP>, define a static variable
holding the <CODE>ResourceBundle</CODE> instance:
<PRE>
public static ResourceBundle myResources =
ResourceBundle.getBundle("domain-name");
</PRE>
All classes containing internationalized strings then contain
<PRE>
private static ResourceBundle res = Util.myResources;
private static String _(String s) { return res.getString(s); }
</PRE>
and the shorthand is used like this:
<PRE>
System.out.println(_("Operation completed."));
</PRE>
<LI>
You add a class with a very short name, say <SAMP>‘S’</SAMP>, containing just the
definition of the resource bundle and of the shorthand:
<PRE>
public class S {
public static ResourceBundle myResources =
ResourceBundle.getBundle("domain-name");
public static String _(String s) {
return myResources.getString(s);
}
}
</PRE>
and the shorthand is used like this:
<PRE>
System.out.println(S._("Operation completed."));
</PRE>
</UL>
<P>
Which of the three idioms you choose, will depend on whether your project
requires portability to Java versions prior to Java 1.5 and, if so, whether
copying two lines of codes into every class is more acceptable in your project
than a class with a single-letter name.
</P>
<H3><A NAME="SEC298" HREF="gettext_toc.html#TOC298">15.5.12 C#</A></H3>
<P>
<A NAME="IDX1279"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
pnet, pnetlib 0.6.2 or newer, or mono 0.29 or newer
<DT>File extension
<DD>
<CODE>cs</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>, <CODE>@"abc"</CODE>
<DT>gettext shorthand
<DD>
_("abc")
<DT>gettext/ngettext functions
<DD>
<CODE>GettextResourceManager.GetString</CODE>,
<CODE>GettextResourceManager.GetPluralString</CODE>
<CODE>GettextResourceManager.GetParticularString</CODE>
<CODE>GettextResourceManager.GetParticularPluralString</CODE>
<DT>textdomain
<DD>
<CODE>new GettextResourceManager(domain)</CODE>
<DT>bindtextdomain
<DD>
---, compiled message catalogs are located in subdirectories of the directory
containing the executable
<DT>setlocale
<DD>
automatic
<DT>Prerequisite
<DD>
---
<DT>Use or emulate GNU gettext
<DD>
---, uses a C# specific message catalog format
<DT>Extractor
<DD>
<CODE>xgettext -k_</CODE>
<DT>Formatting with positions
<DD>
<CODE>String.Format "{1} {0}"</CODE>
<DT>Portability
<DD>
fully portable
<DT>po-mode marking
<DD>
---
</DL>
<P>
Before marking strings as internationalizable, uses of the string
concatenation operator need to be converted to <CODE>String.Format</CODE>
invocations. For example, <CODE>"file "+filename+" not found"</CODE> becomes
<CODE>String.Format("file {0} not found", filename)</CODE>.
Only after this is done, can the strings be marked and extracted.
</P>
<P>
GNU gettext uses the native C#/.NET internationalization mechanism, namely
the classes <CODE>ResourceManager</CODE> and <CODE>ResourceSet</CODE>. Applications
use the <CODE>ResourceManager</CODE> methods to retrieve the native language
translation of strings. An instance of <CODE>ResourceSet</CODE> is the in-memory
representation of a message catalog file. The <CODE>ResourceManager</CODE> loads
and accesses <CODE>ResourceSet</CODE> instances as needed to look up the
translations.
</P>
<P>
There are two formats of <CODE>ResourceSet</CODE>s that can be directly loaded by
the C# runtime: <CODE>.resources</CODE> files and <CODE>.dll</CODE> files.
</P>
<UL>
<LI>
The <CODE>.resources</CODE> format is a binary file usually generated through the
<CODE>resgen</CODE> or <CODE>monoresgen</CODE> utility, but which doesn't support plural
forms. <CODE>.resources</CODE> files can also be embedded in .NET <CODE>.exe</CODE> files.
This only affects whether a file system access is performed to load the message
catalog; it doesn't affect the contents of the message catalog.
<LI>
On the other hand, the <CODE>.dll</CODE> format is a binary file that is compiled
from <CODE>.cs</CODE> source code and can support plural forms (provided it is
accessed through the GNU gettext API, see below).
</UL>
<P>
Note that these .NET <CODE>.dll</CODE> and <CODE>.exe</CODE> files are not tied to a
particular platform; their file format and GNU gettext for C# can be used
on any platform.
</P>
<P>
To convert a PO file to a <CODE>.resources</CODE> file, the <CODE>msgfmt</CODE> program
can be used with the option <SAMP>‘--csharp-resources’</SAMP>. To convert a
<CODE>.resources</CODE> file back to a PO file, the <CODE>msgunfmt</CODE> program can be
used with the option <SAMP>‘--csharp-resources’</SAMP>. You can also, in some cases,
use the <CODE>resgen</CODE> program (from the <CODE>pnet</CODE> package) or the
<CODE>monoresgen</CODE> program (from the <CODE>mono</CODE>/<CODE>mcs</CODE> package). These
programs can also convert a <CODE>.resources</CODE> file back to a PO file. But
beware: as of this writing (January 2004), the <CODE>monoresgen</CODE> converter is
quite buggy and the <CODE>resgen</CODE> converter ignores the encoding of the PO
files.
</P>
<P>
To convert a PO file to a <CODE>.dll</CODE> file, the <CODE>msgfmt</CODE> program can be
used with the option <CODE>--csharp</CODE>. The result will be a <CODE>.dll</CODE> file
containing a subclass of <CODE>GettextResourceSet</CODE>, which itself is a subclass
of <CODE>ResourceSet</CODE>. To convert a <CODE>.dll</CODE> file containing a
<CODE>GettextResourceSet</CODE> subclass back to a PO file, the <CODE>msgunfmt</CODE>
program can be used with the option <CODE>--csharp</CODE>.
</P>
<P>
The advantages of the <CODE>.dll</CODE> format over the <CODE>.resources</CODE> format
are:
</P>
<OL>
<LI>
Freedom to localize: Users can add their own translations to an application
after it has been built and distributed. Whereas when the programmer uses
a <CODE>ResourceManager</CODE> constructor provided by the system, the set of
<CODE>.resources</CODE> files for an application must be specified when the
application is built and cannot be extended afterwards.
<LI>
Plural handling: A message catalog in <CODE>.dll</CODE> format supports the plural
handling function <CODE>GetPluralString</CODE>. Whereas <CODE>.resources</CODE> files can
only contain data and only support lookups that depend on a single string.
<LI>
Context handling: A message catalog in <CODE>.dll</CODE> format supports the
query-with-context functions <CODE>GetParticularString</CODE> and
<CODE>GetParticularPluralString</CODE>. Whereas <CODE>.resources</CODE> files can
only contain data and only support lookups that depend on a single string.
<LI>
The <CODE>GettextResourceManager</CODE> that loads the message catalogs in
<CODE>.dll</CODE> format also provides for inheritance on a per-message basis.
For example, in Austrian (<CODE>de_AT</CODE>) locale, translations from the German
(<CODE>de</CODE>) message catalog will be used for messages not found in the
Austrian message catalog. This has the consequence that the Austrian
translators need only translate those few messages for which the translation
into Austrian differs from the German one. Whereas when working with
<CODE>.resources</CODE> files, each message catalog must provide the translations
of all messages by itself.
<LI>
The <CODE>GettextResourceManager</CODE> that loads the message catalogs in
<CODE>.dll</CODE> format also provides for a fallback: The English <VAR>msgid</VAR> is
returned when no translation can be found. Whereas when working with
<CODE>.resources</CODE> files, a language-neutral <CODE>.resources</CODE> file must
explicitly be provided as a fallback.
</OL>
<P>
On the side of the programmatic APIs, the programmer can use either the
standard <CODE>ResourceManager</CODE> API and the GNU <CODE>GettextResourceManager</CODE>
API. The latter is an extension of the former, because
<CODE>GettextResourceManager</CODE> is a subclass of <CODE>ResourceManager</CODE>.
</P>
<OL>
<LI>
The <CODE>System.Resources.ResourceManager</CODE> API.
This API works with resources in <CODE>.resources</CODE> format.
The creation of the <CODE>ResourceManager</CODE> is done through
<PRE>
new ResourceManager(domainname, Assembly.GetExecutingAssembly())
</PRE>
The <CODE>GetString</CODE> function returns a string's translation. Note that this
function returns null when a translation is missing (i.e. not even found in
the fallback resource file).
<LI>
The <CODE>GNU.Gettext.GettextResourceManager</CODE> API.
This API works with resources in <CODE>.dll</CODE> format.
Reference documentation is in the
<A HREF="csharpdoc/index.html">csharpdoc directory</A>.
The creation of the <CODE>ResourceManager</CODE> is done through
<PRE>
new GettextResourceManager(domainname)
</PRE>
The <CODE>GetString</CODE> function returns a string's translation. Note that when
a translation is missing, the <VAR>msgid</VAR> argument is returned unchanged.
The <CODE>GetPluralString</CODE> function returns a string translation with plural
handling, like the <CODE>ngettext</CODE> function in C.
The <CODE>GetParticularString</CODE> function returns a string's translation,
specific to a particular context, like the <CODE>pgettext</CODE> function in C.
Note that when a translation is missing, the <VAR>msgid</VAR> argument is returned
unchanged.
The <CODE>GetParticularPluralString</CODE> function returns a string translation,
specific to a particular context, with plural handling, like the
<CODE>npgettext</CODE> function in C.
<A NAME="IDX1280"></A>
To use this API, one needs the <CODE>GNU.Gettext.dll</CODE> file which is part of
the GNU gettext package and distributed under the LGPL.
</OL>
<P>
You can also mix both approaches: use the
<CODE>GNU.Gettext.GettextResourceManager</CODE> constructor, but otherwise use
only the <CODE>ResourceManager</CODE> type and only the <CODE>GetString</CODE> method.
This is appropriate when you want to profit from the tools for PO files,
but don't want to change an existing source code that uses
<CODE>ResourceManager</CODE> and don't (yet) need the <CODE>GetPluralString</CODE> method.
</P>
<P>
Two examples, using the second API, are available in the <TT>‘examples’</TT>
directory: <CODE>hello-csharp</CODE>, <CODE>hello-csharp-forms</CODE>.
</P>
<P>
Now, to make use of the API and define a shorthand for <SAMP>‘GetString’</SAMP>,
there are two idioms that you can choose from:
</P>
<UL>
<LI>
In a unique class of your project, say <SAMP>‘Util’</SAMP>, define a static variable
holding the <CODE>ResourceManager</CODE> instance:
<PRE>
public static GettextResourceManager MyResourceManager =
new GettextResourceManager("domain-name");
</PRE>
All classes containing internationalized strings then contain
<PRE>
private static GettextResourceManager Res = Util.MyResourceManager;
private static String _(String s) { return Res.GetString(s); }
</PRE>
and the shorthand is used like this:
<PRE>
Console.WriteLine(_("Operation completed."));
</PRE>
<LI>
You add a class with a very short name, say <SAMP>‘S’</SAMP>, containing just the
definition of the resource manager and of the shorthand:
<PRE>
public class S {
public static GettextResourceManager MyResourceManager =
new GettextResourceManager("domain-name");
public static String _(String s) {
return MyResourceManager.GetString(s);
}
}
</PRE>
and the shorthand is used like this:
<PRE>
Console.WriteLine(S._("Operation completed."));
</PRE>
</UL>
<P>
Which of the two idioms you choose, will depend on whether copying two lines
of codes into every class is more acceptable in your project than a class
with a single-letter name.
</P>
<H3><A NAME="SEC299" HREF="gettext_toc.html#TOC299">15.5.13 GNU awk</A></H3>
<P>
<A NAME="IDX1281"></A>
<A NAME="IDX1282"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
gawk 3.1 or newer
<DT>File extension
<DD>
<CODE>awk</CODE>, <CODE>gawk</CODE>, <CODE>twjr</CODE>.
The file extension <CODE>twjr</CODE> is used by TexiWeb Jr
(<A HREF="https://github.com/arnoldrobbins/texiwebjr">https://github.com/arnoldrobbins/texiwebjr</A>).
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>_"abc"</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>dcgettext</CODE>, missing <CODE>dcngettext</CODE> in gawk-3.1.0
<DT>textdomain
<DD>
<CODE>TEXTDOMAIN</CODE> variable
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function
<DT>setlocale
<DD>
automatic, but missing <CODE>setlocale (LC_MESSAGES, "")</CODE> in gawk-3.1.0
<DT>Prerequisite
<DD>
---
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
<CODE>printf "%2$d %1$d"</CODE> (GNU awk only)
<DT>Portability
<DD>
On platforms without gettext, no translation. On non-GNU awks, you must
define <CODE>dcgettext</CODE>, <CODE>dcngettext</CODE> and <CODE>bindtextdomain</CODE>
yourself.
<DT>po-mode marking
<DD>
---
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-gawk</CODE>.
</P>
<H3><A NAME="SEC300" HREF="gettext_toc.html#TOC300">15.5.14 Pascal - Free Pascal Compiler</A></H3>
<P>
<A NAME="IDX1283"></A>
<A NAME="IDX1284"></A>
<A NAME="IDX1285"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
fpk
<DT>File extension
<DD>
<CODE>pp</CODE>, <CODE>pas</CODE>
<DT>String syntax
<DD>
<CODE>'abc'</CODE>
<DT>gettext shorthand
<DD>
automatic
<DT>gettext/ngettext functions
<DD>
---, use <CODE>ResourceString</CODE> data type instead
<DT>textdomain
<DD>
---, use <CODE>TranslateResourceStrings</CODE> function instead
<DT>bindtextdomain
<DD>
---, use <CODE>TranslateResourceStrings</CODE> function instead
<DT>setlocale
<DD>
automatic, but uses only LANG, not LC_MESSAGES or LC_ALL
<DT>Prerequisite
<DD>
<CODE>{$mode delphi}</CODE> or <CODE>{$mode objfpc}</CODE><BR><CODE>uses gettext;</CODE>
<DT>Use or emulate GNU gettext
<DD>
emulate partially
<DT>Extractor
<DD>
<CODE>ppc386</CODE> followed by <CODE>xgettext</CODE> or <CODE>rstconv</CODE>
<DT>Formatting with positions
<DD>
<CODE>uses sysutils;</CODE><BR><CODE>format "%1:d %0:d"</CODE>
<DT>Portability
<DD>
?
<DT>po-mode marking
<DD>
---
</DL>
<P>
The Pascal compiler has special support for the <CODE>ResourceString</CODE> data
type. It generates a <CODE>.rst</CODE> file. This is then converted to a
<CODE>.pot</CODE> file by use of <CODE>xgettext</CODE> or <CODE>rstconv</CODE>. At runtime,
a <CODE>.mo</CODE> file corresponding to translations of this <CODE>.pot</CODE> file
can be loaded using the <CODE>TranslateResourceStrings</CODE> function in the
<CODE>gettext</CODE> unit.
</P>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-pascal</CODE>.
</P>
<H3><A NAME="SEC301" HREF="gettext_toc.html#TOC301">15.5.15 wxWidgets library</A></H3>
<P>
<A NAME="IDX1286"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
wxGTK, gettext
<DT>File extension
<DD>
<CODE>cpp</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>_("abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>wxLocale::GetString</CODE>, <CODE>wxGetTranslation</CODE>
<DT>textdomain
<DD>
<CODE>wxLocale::AddCatalog</CODE>
<DT>bindtextdomain
<DD>
<CODE>wxLocale::AddCatalogLookupPathPrefix</CODE>
<DT>setlocale
<DD>
<CODE>wxLocale::Init</CODE>, <CODE>wxSetLocale</CODE>
<DT>Prerequisite
<DD>
<CODE>#include <wx/intl.h></CODE>
<DT>Use or emulate GNU gettext
<DD>
emulate, see <CODE>include/wx/intl.h</CODE> and <CODE>src/common/intl.cpp</CODE>
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
wxString::Format supports positions if and only if the system has
<CODE>wprintf()</CODE>, <CODE>vswprintf()</CODE> functions and they support positions
according to POSIX.
<DT>Portability
<DD>
fully portable
<DT>po-mode marking
<DD>
yes
</DL>
<H3><A NAME="SEC302" HREF="gettext_toc.html#TOC302">15.5.16 YCP - YaST2 scripting language</A></H3>
<P>
<A NAME="IDX1287"></A>
<A NAME="IDX1288"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
libycp, libycp-devel, yast2-core, yast2-core-devel
<DT>File extension
<DD>
<CODE>ycp</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>_("abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>_()</CODE> with 1 or 3 arguments
<DT>textdomain
<DD>
<CODE>textdomain</CODE> statement
<DT>bindtextdomain
<DD>
---
<DT>setlocale
<DD>
---
<DT>Prerequisite
<DD>
---
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
<CODE>sformat "%2 %1"</CODE>
<DT>Portability
<DD>
fully portable
<DT>po-mode marking
<DD>
---
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-ycp</CODE>.
</P>
<H3><A NAME="SEC303" HREF="gettext_toc.html#TOC303">15.5.17 Tcl - Tk's scripting language</A></H3>
<P>
<A NAME="IDX1289"></A>
<A NAME="IDX1290"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
tcl
<DT>File extension
<DD>
<CODE>tcl</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>[_ "abc"]</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>::msgcat::mc</CODE>
<DT>textdomain
<DD>
---
<DT>bindtextdomain
<DD>
---, use <CODE>::msgcat::mcload</CODE> instead
<DT>setlocale
<DD>
automatic, uses LANG, but ignores LC_MESSAGES and LC_ALL
<DT>Prerequisite
<DD>
<CODE>package require msgcat</CODE>
<BR><CODE>proc _ {s} {return [::msgcat::mc $s]}</CODE>
<DT>Use or emulate GNU gettext
<DD>
---, uses a Tcl specific message catalog format
<DT>Extractor
<DD>
<CODE>xgettext -k_</CODE>
<DT>Formatting with positions
<DD>
<CODE>format "%2\$d %1\$d"</CODE>
<DT>Portability
<DD>
fully portable
<DT>po-mode marking
<DD>
---
</DL>
<P>
Two examples are available in the <TT>‘examples’</TT> directory:
<CODE>hello-tcl</CODE>, <CODE>hello-tcl-tk</CODE>.
</P>
<P>
Before marking strings as internationalizable, substitutions of variables
into the string need to be converted to <CODE>format</CODE> applications. For
example, <CODE>"file $filename not found"</CODE> becomes
<CODE>[format "file %s not found" $filename]</CODE>.
Only after this is done, can the strings be marked and extracted.
After marking, this example becomes
<CODE>[format [_ "file %s not found"] $filename]</CODE> or
<CODE>[msgcat::mc "file %s not found" $filename]</CODE>. Note that the
<CODE>msgcat::mc</CODE> function implicitly calls <CODE>format</CODE> when more than one
argument is given.
</P>
<H3><A NAME="SEC304" HREF="gettext_toc.html#TOC304">15.5.18 Perl</A></H3>
<P>
<A NAME="IDX1291"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
perl
<DT>File extension
<DD>
<CODE>pl</CODE>, <CODE>PL</CODE>, <CODE>pm</CODE>, <CODE>perl</CODE>, <CODE>cgi</CODE>
<DT>String syntax
<DD>
<UL>
<LI><CODE>"abc"</CODE>
<LI><CODE>'abc'</CODE>
<LI><CODE>qq (abc)</CODE>
<LI><CODE>q (abc)</CODE>
<LI><CODE>qr /abc/</CODE>
<LI><CODE>qx (/bin/date)</CODE>
<LI><CODE>/pattern match/</CODE>
<LI><CODE>?pattern match?</CODE>
<LI><CODE>s/substitution/operators/</CODE>
<LI><CODE>$tied_hash{"message"}</CODE>
<LI><CODE>$tied_hash_reference->{"message"}</CODE>
<LI>etc., issue the command <SAMP>‘man perlsyn’</SAMP> for details
</UL>
<DT>gettext shorthand
<DD>
<CODE>__</CODE> (double underscore)
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>, <CODE>dgettext</CODE>, <CODE>dcgettext</CODE>, <CODE>ngettext</CODE>,
<CODE>dngettext</CODE>, <CODE>dcngettext</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE> function
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function
<DT>bind_textdomain_codeset
<DD>
<CODE>bind_textdomain_codeset</CODE> function
<DT>setlocale
<DD>
Use <CODE>setlocale (LC_ALL, "");</CODE>
<DT>Prerequisite
<DD>
<CODE>use POSIX;</CODE>
<BR><CODE>use Locale::TextDomain;</CODE> (included in the package libintl-perl
which is available on the Comprehensive Perl Archive Network CPAN,
http://www.cpan.org/).
<DT>Use or emulate GNU gettext
<DD>
platform dependent: gettext_pp emulates, gettext_xs uses GNU gettext
<DT>Extractor
<DD>
<CODE>xgettext -k__ -k\$__ -k%__ -k__x -k__n:1,2 -k__nx:1,2 -k__xn:1,2 -kN__ -k</CODE>
<DT>Formatting with positions
<DD>
Both kinds of format strings support formatting with positions.
<BR><CODE>printf "%2\$d %1\$d", ...</CODE> (requires Perl 5.8.0 or newer)
<BR><CODE>__expand("[new] replaces [old]", old => $oldvalue, new => $newvalue)</CODE>
<DT>Portability
<DD>
The <CODE>libintl-perl</CODE> package is platform independent but is not
part of the Perl core. The programmer is responsible for
providing a dummy implementation of the required functions if the
package is not installed on the target system.
<DT>po-mode marking
<DD>
---
<DT>Documentation
<DD>
Included in <CODE>libintl-perl</CODE>, available on CPAN
(http://www.cpan.org/).
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-perl</CODE>.
</P>
<P>
<A NAME="IDX1292"></A>
</P>
<P>
The <CODE>xgettext</CODE> parser backend for Perl differs significantly from
the parser backends for other programming languages, just as Perl
itself differs significantly from other programming languages. The
Perl parser backend offers many more string marking facilities than
the other backends but it also has some Perl specific limitations, the
worst probably being its imperfectness.
</P>
<H4><A NAME="SEC305" HREF="gettext_toc.html#TOC305">15.5.18.1 General Problems Parsing Perl Code</A></H4>
<P>
It is often heard that only Perl can parse Perl. This is not true.
Perl cannot be <EM>parsed</EM> at all, it can only be <EM>executed</EM>.
Perl has various built-in ambiguities that can only be resolved at runtime.
</P>
<P>
The following example may illustrate one common problem:
</P>
<PRE>
print gettext "Hello World!";
</PRE>
<P>
Although this example looks like a bullet-proof case of a function
invocation, it is not:
</P>
<PRE>
open gettext, ">testfile" or die;
print gettext "Hello world!"
</PRE>
<P>
In this context, the string <CODE>gettext</CODE> looks more like a
file handle. But not necessarily:
</P>
<PRE>
use Locale::Messages qw (:libintl_h);
open gettext ">testfile" or die;
print gettext "Hello world!";
</PRE>
<P>
Now, the file is probably syntactically incorrect, provided that the module
<CODE>Locale::Messages</CODE> found first in the Perl include path exports a
function <CODE>gettext</CODE>. But what if the module
<CODE>Locale::Messages</CODE> really looks like this?
</P>
<PRE>
use vars qw (*gettext);
1;
</PRE>
<P>
In this case, the string <CODE>gettext</CODE> will be interpreted as a file
handle again, and the above example will create a file <TT>‘testfile’</TT>
and write the string “Hello world!” into it. Even advanced
control flow analysis will not really help:
</P>
<PRE>
if (0.5 < rand) {
eval "use Sane";
} else {
eval "use InSane";
}
print gettext "Hello world!";
</PRE>
<P>
If the module <CODE>Sane</CODE> exports a function <CODE>gettext</CODE> that does
what we expect, and the module <CODE>InSane</CODE> opens a file for writing
and associates the <EM>handle</EM> <CODE>gettext</CODE> with this output
stream, we are clueless again about what will happen at runtime. It is
completely unpredictable. The truth is that Perl has so many ways to
fill its symbol table at runtime that it is impossible to interpret a
particular piece of code without executing it.
</P>
<P>
Of course, <CODE>xgettext</CODE> will not execute your Perl sources while
scanning for translatable strings, but rather use heuristics in order
to guess what you meant.
</P>
<P>
Another problem is the ambiguity of the slash and the question mark.
Their interpretation depends on the context:
</P>
<PRE>
# A pattern match.
print "OK\n" if /foobar/;
# A division.
print 1 / 2;
# Another pattern match.
print "OK\n" if ?foobar?;
# Conditional.
print $x ? "foo" : "bar";
</PRE>
<P>
The slash may either act as the division operator or introduce a
pattern match, whereas the question mark may act as the ternary
conditional operator or as a pattern match, too. Other programming
languages like <CODE>awk</CODE> present similar problems, but the consequences of a
misinterpretation are particularly nasty with Perl sources. In <CODE>awk</CODE>
for instance, a statement can never exceed one line and the parser
can recover from a parsing error at the next newline and interpret
the rest of the input stream correctly. Perl is different, as a
pattern match is terminated by the next appearance of the delimiter
(the slash or the question mark) in the input stream, regardless of
the semantic context. If a slash is really a division sign but
mis-interpreted as a pattern match, the rest of the input file is most
probably parsed incorrectly.
</P>
<P>
There are certain cases, where the ambiguity cannot be resolved at all:
</P>
<PRE>
$x = wantarray ? 1 : 0;
</PRE>
<P>
The Perl built-in function <CODE>wantarray</CODE> does not accept any arguments.
The Perl parser therefore knows that the question mark does not start
a regular expression but is the ternary conditional operator.
</P>
<PRE>
sub wantarrays {}
$x = wantarrays ? 1 : 0;
</PRE>
<P>
Now the situation is different. The function <CODE>wantarrays</CODE> takes
a variable number of arguments (like any non-prototyped Perl function).
The question mark is now the delimiter of a pattern match, and hence
the piece of code does not compile.
</P>
<PRE>
sub wantarrays() {}
$x = wantarrays ? 1 : 0;
</PRE>
<P>
Now the function is prototyped, Perl knows that it does not accept any
arguments, and the question mark is therefore interpreted as the
ternaray operator again. But that unfortunately outsmarts <CODE>xgettext</CODE>.
</P>
<P>
The Perl parser in <CODE>xgettext</CODE> cannot know whether a function has
a prototype and what that prototype would look like. It therefore makes
an educated guess. If a function is known to be a Perl built-in and
this function does not accept any arguments, a following question mark
or slash is treated as an operator, otherwise as the delimiter of a
following regular expression. The Perl built-ins that do not accept
arguments are <CODE>wantarray</CODE>, <CODE>fork</CODE>, <CODE>time</CODE>, <CODE>times</CODE>,
<CODE>getlogin</CODE>, <CODE>getppid</CODE>, <CODE>getpwent</CODE>, <CODE>getgrent</CODE>,
<CODE>gethostent</CODE>, <CODE>getnetent</CODE>, <CODE>getprotoent</CODE>, <CODE>getservent</CODE>,
<CODE>setpwent</CODE>, <CODE>setgrent</CODE>, <CODE>endpwent</CODE>, <CODE>endgrent</CODE>,
<CODE>endhostent</CODE>, <CODE>endnetent</CODE>, <CODE>endprotoent</CODE>, and
<CODE>endservent</CODE>.
</P>
<P>
If you find that <CODE>xgettext</CODE> fails to extract strings from
portions of your sources, you should therefore look out for slashes
and/or question marks preceding these sections. You may have come
across a bug in <CODE>xgettext</CODE>'s Perl parser (and of course you
should report that bug). In the meantime you should consider to
reformulate your code in a manner less challenging to <CODE>xgettext</CODE>.
</P>
<P>
In particular, if the parser is too dumb to see that a function
does not accept arguments, use parentheses:
</P>
<PRE>
$x = somefunc() ? 1 : 0;
$y = (somefunc) ? 1 : 0;
</PRE>
<P>
In fact the Perl parser itself has similar problems and warns you
about such constructs.
</P>
<H4><A NAME="SEC306" HREF="gettext_toc.html#TOC306">15.5.18.2 Which keywords will xgettext look for?</A></H4>
<P>
<A NAME="IDX1293"></A>
</P>
<P>
Unless you instruct <CODE>xgettext</CODE> otherwise by invoking it with one
of the options <CODE>--keyword</CODE> or <CODE>-k</CODE>, it will recognize the
following keywords in your Perl sources:
</P>
<UL>
<LI><CODE>gettext</CODE>
<LI><CODE>dgettext</CODE>
<LI><CODE>dcgettext</CODE>
<LI><CODE>ngettext:1,2</CODE>
The first (singular) and the second (plural) argument will be
extracted.
<LI><CODE>dngettext:1,2</CODE>
The first (singular) and the second (plural) argument will be
extracted.
<LI><CODE>dcngettext:1,2</CODE>
The first (singular) and the second (plural) argument will be
extracted.
<LI><CODE>gettext_noop</CODE>
<LI><CODE>%gettext</CODE>
The keys of lookups into the hash <CODE>%gettext</CODE> will be extracted.
<LI><CODE>$gettext</CODE>
The keys of lookups into the hash reference <CODE>$gettext</CODE> will be extracted.
</UL>
<H4><A NAME="SEC307" HREF="gettext_toc.html#TOC307">15.5.18.3 How to Extract Hash Keys</A></H4>
<P>
<A NAME="IDX1294"></A>
</P>
<P>
Translating messages at runtime is normally performed by looking up the
original string in the translation database and returning the
translated version. The “natural” Perl implementation is a hash
lookup, and, of course, <CODE>xgettext</CODE> supports such practice.
</P>
<PRE>
print __"Hello world!";
print $__{"Hello world!"};
print $__->{"Hello world!"};
print $$__{"Hello world!"};
</PRE>
<P>
The above four lines all do the same thing. The Perl module
<CODE>Locale::TextDomain</CODE> exports by default a hash <CODE>%__</CODE> that
is tied to the function <CODE>__()</CODE>. It also exports a reference
<CODE>$__</CODE> to <CODE>%__</CODE>.
</P>
<P>
If an argument to the <CODE>xgettext</CODE> option <CODE>--keyword</CODE>,
resp. <CODE>-k</CODE> starts with a percent sign, the rest of the keyword is
interpreted as the name of a hash. If it starts with a dollar
sign, the rest of the keyword is interpreted as a reference to a
hash.
</P>
<P>
Note that you can omit the quotation marks (single or double) around
the hash key (almost) whenever Perl itself allows it:
</P>
<PRE>
print $gettext{Error};
</PRE>
<P>
The exact rule is: You can omit the surrounding quotes, when the hash
key is a valid C (!) identifier, i.e. when it starts with an
underscore or an ASCII letter and is followed by an arbitrary number
of underscores, ASCII letters or digits. Other Unicode characters
are <EM>not</EM> allowed, regardless of the <CODE>use utf8</CODE> pragma.
</P>
<H4><A NAME="SEC308" HREF="gettext_toc.html#TOC308">15.5.18.4 What are Strings And Quote-like Expressions?</A></H4>
<P>
<A NAME="IDX1295"></A>
</P>
<P>
Perl offers a plethora of different string constructs. Those that can
be used either as arguments to functions or inside braces for hash
lookups are generally supported by <CODE>xgettext</CODE>.
</P>
<UL>
<LI><STRONG>double-quoted strings</STRONG>
<BR>
<PRE>
print gettext "Hello World!";
</PRE>
<LI><STRONG>single-quoted strings</STRONG>
<BR>
<PRE>
print gettext 'Hello World!';
</PRE>
<LI><STRONG>the operator qq</STRONG>
<BR>
<PRE>
print gettext qq |Hello World!|;
print gettext qq <E-mail: <guido\@imperia.net>>;
</PRE>
The operator <CODE>qq</CODE> is fully supported. You can use arbitrary
delimiters, including the four bracketing delimiters (round, angle,
square, curly) that nest.
<LI><STRONG>the operator q</STRONG>
<BR>
<PRE>
print gettext q |Hello World!|;
print gettext q <E-mail: <guido@imperia.net>>;
</PRE>
The operator <CODE>q</CODE> is fully supported. You can use arbitrary
delimiters, including the four bracketing delimiters (round, angle,
square, curly) that nest.
<LI><STRONG>the operator qx</STRONG>
<BR>
<PRE>
print gettext qx ;LANGUAGE=C /bin/date;
print gettext qx [/usr/bin/ls | grep '^[A-Z]*'];
</PRE>
The operator <CODE>qx</CODE> is fully supported. You can use arbitrary
delimiters, including the four bracketing delimiters (round, angle,
square, curly) that nest.
The example is actually a useless use of <CODE>gettext</CODE>. It will
invoke the <CODE>gettext</CODE> function on the output of the command
specified with the <CODE>qx</CODE> operator. The feature was included
in order to make the interface consistent (the parser will extract
all strings and quote-like expressions).
<LI><STRONG>here documents</STRONG>
<BR>
<PRE>
print gettext <<'EOF';
program not found in $PATH
EOF
print ngettext <<EOF, <<"EOF";
one file deleted
EOF
several files deleted
EOF
</PRE>
Here-documents are recognized. If the delimiter is enclosed in single
quotes, the string is not interpolated. If it is enclosed in double
quotes or has no quotes at all, the string is interpolated.
Delimiters that start with a digit are not supported!
</UL>
<H4><A NAME="SEC309" HREF="gettext_toc.html#TOC309">15.5.18.5 Invalid Uses Of String Interpolation</A></H4>
<P>
<A NAME="IDX1296"></A>
</P>
<P>
Perl is capable of interpolating variables into strings. This offers
some nice features in localized programs but can also lead to
problems.
</P>
<P>
A common error is a construct like the following:
</P>
<PRE>
print gettext "This is the program $0!\n";
</PRE>
<P>
Perl will interpolate at runtime the value of the variable <CODE>$0</CODE>
into the argument of the <CODE>gettext()</CODE> function. Hence, this
argument is not a string constant but a variable argument (<CODE>$0</CODE>
is a global variable that holds the name of the Perl script being
executed). The interpolation is performed by Perl before the string
argument is passed to <CODE>gettext()</CODE> and will therefore depend on
the name of the script which can only be determined at runtime.
Consequently, it is almost impossible that a translation can be looked
up at runtime (except if, by accident, the interpolated string is found
in the message catalog).
</P>
<P>
The <CODE>xgettext</CODE> program will therefore terminate parsing with a fatal
error if it encounters a variable inside of an extracted string. In
general, this will happen for all kinds of string interpolations that
cannot be safely performed at compile time. If you absolutely know
what you are doing, you can always circumvent this behavior:
</P>
<PRE>
my $know_what_i_am_doing = "This is program $0!\n";
print gettext $know_what_i_am_doing;
</PRE>
<P>
Since the parser only recognizes strings and quote-like expressions,
but not variables or other terms, the above construct will be
accepted. You will have to find another way, however, to let your
original string make it into your message catalog.
</P>
<P>
If invoked with the option <CODE>--extract-all</CODE>, resp. <CODE>-a</CODE>,
variable interpolation will be accepted. Rationale: You will
generally use this option in order to prepare your sources for
internationalization.
</P>
<P>
Please see the manual page <SAMP>‘man perlop’</SAMP> for details of strings and
quote-like expressions that are subject to interpolation and those
that are not. Safe interpolations (that will not lead to a fatal
error) are:
</P>
<UL>
<LI>the escape sequences <CODE>\t</CODE> (tab, HT, TAB), <CODE>\n</CODE>
(newline, NL), <CODE>\r</CODE> (return, CR), <CODE>\f</CODE> (form feed, FF),
<CODE>\b</CODE> (backspace, BS), <CODE>\a</CODE> (alarm, bell, BEL), and <CODE>\e</CODE>
(escape, ESC).
<LI>octal chars, like <CODE>\033</CODE>
<BR>
Note that octal escapes in the range of 400-777 are translated into a
UTF-8 representation, regardless of the presence of the <CODE>use utf8</CODE> pragma.
<LI>hex chars, like <CODE>\x1b</CODE>
<LI>wide hex chars, like <CODE>\x{263a}</CODE>
<BR>
Note that this escape is translated into a UTF-8 representation,
regardless of the presence of the <CODE>use utf8</CODE> pragma.
<LI>control chars, like <CODE>\c[</CODE> (CTRL-[)
<LI>named Unicode chars, like <CODE>\N{LATIN CAPITAL LETTER C WITH CEDILLA}</CODE>
<BR>
Note that this escape is translated into a UTF-8 representation,
regardless of the presence of the <CODE>use utf8</CODE> pragma.
</UL>
<P>
The following escapes are considered partially safe:
</P>
<UL>
<LI><CODE>\l</CODE> lowercase next char
<LI><CODE>\u</CODE> uppercase next char
<LI><CODE>\L</CODE> lowercase till \E
<LI><CODE>\U</CODE> uppercase till \E
<LI><CODE>\E</CODE> end case modification
<LI><CODE>\Q</CODE> quote non-word characters till \E
</UL>
<P>
These escapes are only considered safe if the string consists of
ASCII characters only. Translation of characters outside the range
defined by ASCII is locale-dependent and can actually only be performed
at runtime; <CODE>xgettext</CODE> doesn't do these locale-dependent translations
at extraction time.
</P>
<P>
Except for the modifier <CODE>\Q</CODE>, these translations, albeit valid,
are generally useless and only obfuscate your sources. If a
translation can be safely performed at compile time you can just as
well write what you mean.
</P>
<H4><A NAME="SEC310" HREF="gettext_toc.html#TOC310">15.5.18.6 Valid Uses Of String Interpolation</A></H4>
<P>
<A NAME="IDX1297"></A>
</P>
<P>
Perl is often used to generate sources for other programming languages
or arbitrary file formats. Web applications that output HTML code
make a prominent example for such usage.
</P>
<P>
You will often come across situations where you want to intersperse
code written in the target (programming) language with translatable
messages, like in the following HTML example:
</P>
<PRE>
print gettext <<EOF;
<h1>My Homepage</h1>
<script language="JavaScript"><!--
for (i = 0; i < 100; ++i) {
alert ("Thank you so much for visiting my homepage!");
}
//--></script>
EOF
</PRE>
<P>
The parser will extract the entire here document, and it will appear
entirely in the resulting PO file, including the JavaScript snippet
embedded in the HTML code. If you exaggerate with constructs like
the above, you will run the risk that the translators of your package
will look out for a less challenging project. You should consider an
alternative expression here:
</P>
<PRE>
print <<EOF;
<h1>$gettext{"My Homepage"}</h1>
<script language="JavaScript"><!--
for (i = 0; i < 100; ++i) {
alert ("$gettext{'Thank you so much for visiting my homepage!'}");
}
//--></script>
EOF
</PRE>
<P>
Only the translatable portions of the code will be extracted here, and
the resulting PO file will begrudgingly improve in terms of readability.
</P>
<P>
You can interpolate hash lookups in all strings or quote-like
expressions that are subject to interpolation (see the manual page
<SAMP>‘man perlop’</SAMP> for details). Double interpolation is invalid, however:
</P>
<PRE>
# TRANSLATORS: Replace "the earth" with the name of your planet.
print gettext qq{Welcome to $gettext->{"the earth"}};
</PRE>
<P>
The <CODE>qq</CODE>-quoted string is recognized as an argument to <CODE>xgettext</CODE> in
the first place, and checked for invalid variable interpolation. The
dollar sign of hash-dereferencing will therefore terminate the parser
with an “invalid interpolation” error.
</P>
<P>
It is valid to interpolate hash lookups in regular expressions:
</P>
<PRE>
if ($var =~ /$gettext{"the earth"}/) {
print gettext "Match!\n";
}
s/$gettext{"U. S. A."}/$gettext{"U. S. A."} $gettext{"(dial +0)"}/g;
</PRE>
<H4><A NAME="SEC311" HREF="gettext_toc.html#TOC311">15.5.18.7 When To Use Parentheses</A></H4>
<P>
<A NAME="IDX1298"></A>
</P>
<P>
In Perl, parentheses around function arguments are mostly optional.
<CODE>xgettext</CODE> will always assume that all
recognized keywords (except for hashes and hash references) are names
of properly prototyped functions, and will (hopefully) only require
parentheses where Perl itself requires them. All constructs in the
following example are therefore ok to use:
</P>
<PRE>
print gettext ("Hello World!\n");
print gettext "Hello World!\n";
print dgettext ($package => "Hello World!\n");
print dgettext $package, "Hello World!\n";
# The "fat comma" => turns the left-hand side argument into a
# single-quoted string!
print dgettext smellovision => "Hello World!\n";
# The following assignment only works with prototyped functions.
# Otherwise, the functions will act as "greedy" list operators and
# eat up all following arguments.
my $anonymous_hash = {
planet => gettext "earth",
cakes => ngettext "one cake", "several cakes", $n,
still => $works,
};
# The same without fat comma:
my $other_hash = {
'planet', gettext "earth",
'cakes', ngettext "one cake", "several cakes", $n,
'still', $works,
};
# Parentheses are only significant for the first argument.
print dngettext 'package', ("one cake", "several cakes", $n), $discarded;
</PRE>
<H4><A NAME="SEC312" HREF="gettext_toc.html#TOC312">15.5.18.8 How To Grok with Long Lines</A></H4>
<P>
<A NAME="IDX1299"></A>
</P>
<P>
The necessity of long messages can often lead to a cumbersome or
unreadable coding style. Perl has several options that may prevent
you from writing unreadable code, and
<CODE>xgettext</CODE> does its best to do likewise. This is where the dot
operator (the string concatenation operator) may come in handy:
</P>
<PRE>
print gettext ("This is a very long"
. " message that is still"
. " readable, because"
. " it is split into"
. " multiple lines.\n");
</PRE>
<P>
Perl is smart enough to concatenate these constant string fragments
into one long string at compile time, and so is
<CODE>xgettext</CODE>. You will only find one long message in the resulting
POT file.
</P>
<P>
Note that the future Perl 6 will probably use the underscore
(<SAMP>‘_’</SAMP>) as the string concatenation operator, and the dot
(<SAMP>‘.’</SAMP>) for dereferencing. This new syntax is not yet supported by
<CODE>xgettext</CODE>.
</P>
<P>
If embedded newline characters are not an issue, or even desired, you
may also insert newline characters inside quoted strings wherever you
feel like it:
</P>
<PRE>
print gettext ("<em>In HTML output
embedded newlines are generally no
problem, since adjacent whitespace
is always rendered into a single
space character.</em>");
</PRE>
<P>
You may also consider to use here documents:
</P>
<PRE>
print gettext <<EOF;
<em>In HTML output
embedded newlines are generally no
problem, since adjacent whitespace
is always rendered into a single
space character.</em>
EOF
</PRE>
<P>
Please do not forget that the line breaks are real, i.e. they
translate into newline characters that will consequently show up in
the resulting POT file.
</P>
<H4><A NAME="SEC313" HREF="gettext_toc.html#TOC313">15.5.18.9 Bugs, Pitfalls, And Things That Do Not Work</A></H4>
<P>
<A NAME="IDX1300"></A>
</P>
<P>
The foregoing sections should have proven that
<CODE>xgettext</CODE> is quite smart in extracting translatable strings from
Perl sources. Yet, some more or less exotic constructs that could be
expected to work, actually do not work.
</P>
<P>
One of the more relevant limitations can be found in the
implementation of variable interpolation inside quoted strings. Only
simple hash lookups can be used there:
</P>
<PRE>
print <<EOF;
$gettext{"The dot operator"
. " does not work"
. "here!"}
Likewise, you cannot @{[ gettext ("interpolate function calls") ]}
inside quoted strings or quote-like expressions.
EOF
</PRE>
<P>
This is valid Perl code and will actually trigger invocations of the
<CODE>gettext</CODE> function at runtime. Yet, the Perl parser in
<CODE>xgettext</CODE> will fail to recognize the strings. A less obvious
example can be found in the interpolation of regular expressions:
</P>
<PRE>
s/<!--START_OF_WEEK-->/gettext ("Sunday")/e;
</PRE>
<P>
The modifier <CODE>e</CODE> will cause the substitution to be interpreted as
an evaluable statement. Consequently, at runtime the function
<CODE>gettext()</CODE> is called, but again, the parser fails to extract the
string “Sunday”. Use a temporary variable as a simple workaround if
you really happen to need this feature:
</P>
<PRE>
my $sunday = gettext "Sunday";
s/<!--START_OF_WEEK-->/$sunday/;
</PRE>
<P>
Hash slices would also be handy but are not recognized:
</P>
<PRE>
my @weekdays = @gettext{'Sunday', 'Monday', 'Tuesday', 'Wednesday',
'Thursday', 'Friday', 'Saturday'};
# Or even:
@weekdays = @gettext{qw (Sunday Monday Tuesday Wednesday Thursday
Friday Saturday) };
</PRE>
<P>
This is perfectly valid usage of the tied hash <CODE>%gettext</CODE> but the
strings are not recognized and therefore will not be extracted.
</P>
<P>
Another caveat of the current version is its rudimentary support for
non-ASCII characters in identifiers. You may encounter serious
problems if you use identifiers with characters outside the range of
'A'-'Z', 'a'-'z', '0'-'9' and the underscore '_'.
</P>
<P>
Maybe some of these missing features will be implemented in future
versions, but since you can always make do without them at minimal effort,
these todos have very low priority.
</P>
<P>
A nasty problem are brace format strings that already contain braces
as part of the normal text, for example the usage strings typically
encountered in programs:
</P>
<PRE>
die "usage: $0 {OPTIONS} FILENAME...\n";
</PRE>
<P>
If you want to internationalize this code with Perl brace format strings,
you will run into a problem:
</P>
<PRE>
die __x ("usage: {program} {OPTIONS} FILENAME...\n", program => $0);
</PRE>
<P>
Whereas <SAMP>‘{program}’</SAMP> is a placeholder, <SAMP>‘{OPTIONS}’</SAMP>
is not and should probably be translated. Yet, there is no way to teach
the Perl parser in <CODE>xgettext</CODE> to recognize the first one, and leave
the other one alone.
</P>
<P>
There are two possible work-arounds for this problem. If you are
sure that your program will run under Perl 5.8.0 or newer (these
Perl versions handle positional parameters in <CODE>printf()</CODE>) or
if you are sure that the translator will not have to reorder the arguments
in her translation -- for example if you have only one brace placeholder
in your string, or if it describes a syntax, like in this one --, you can
mark the string as <CODE>no-perl-brace-format</CODE> and use <CODE>printf()</CODE>:
</P>
<PRE>
# xgettext: no-perl-brace-format
die sprintf ("usage: %s {OPTIONS} FILENAME...\n", $0);
</PRE>
<P>
If you want to use the more portable Perl brace format, you will have to do
put placeholders in place of the literal braces:
</P>
<PRE>
die __x ("usage: {program} {[}OPTIONS{]} FILENAME...\n",
program => $0, '[' => '{', ']' => '}');
</PRE>
<P>
Perl brace format strings know no escaping mechanism. No matter how this
escaping mechanism looked like, it would either give the programmer a
hard time, make translating Perl brace format strings heavy-going, or
result in a performance penalty at runtime, when the format directives
get executed. Most of the time you will happily get along with
<CODE>printf()</CODE> for this special case.
</P>
<H3><A NAME="SEC314" HREF="gettext_toc.html#TOC314">15.5.19 PHP Hypertext Preprocessor</A></H3>
<P>
<A NAME="IDX1301"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
mod_php4, mod_php4-core, phpdoc
<DT>File extension
<DD>
<CODE>php</CODE>, <CODE>php3</CODE>, <CODE>php4</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>, <CODE>'abc'</CODE>
<DT>gettext shorthand
<DD>
<CODE>_("abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>, <CODE>dgettext</CODE>, <CODE>dcgettext</CODE>; starting with PHP 4.2.0
also <CODE>ngettext</CODE>, <CODE>dngettext</CODE>, <CODE>dcngettext</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE> function
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function
<DT>setlocale
<DD>
Programmer must call <CODE>setlocale (LC_ALL, "")</CODE>
<DT>Prerequisite
<DD>
---
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
<CODE>printf "%2\$d %1\$d"</CODE>
<DT>Portability
<DD>
On platforms without gettext, the functions are not available.
<DT>po-mode marking
<DD>
---
</DL>
<P>
An example is available in the <TT>‘examples’</TT> directory: <CODE>hello-php</CODE>.
</P>
<H3><A NAME="SEC315" HREF="gettext_toc.html#TOC315">15.5.20 Pike</A></H3>
<P>
<A NAME="IDX1302"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
roxen
<DT>File extension
<DD>
<CODE>pike</CODE>
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
---
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>, <CODE>dgettext</CODE>, <CODE>dcgettext</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE> function
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function
<DT>setlocale
<DD>
<CODE>setlocale</CODE> function
<DT>Prerequisite
<DD>
<CODE>import Locale.Gettext;</CODE>
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
---
<DT>Formatting with positions
<DD>
---
<DT>Portability
<DD>
On platforms without gettext, the functions are not available.
<DT>po-mode marking
<DD>
---
</DL>
<H3><A NAME="SEC316" HREF="gettext_toc.html#TOC316">15.5.21 GNU Compiler Collection sources</A></H3>
<P>
<A NAME="IDX1303"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
gcc
<DT>File extension
<DD>
<CODE>c</CODE>, <CODE>h</CODE>.
<DT>String syntax
<DD>
<CODE>"abc"</CODE>
<DT>gettext shorthand
<DD>
<CODE>_("abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>, <CODE>dgettext</CODE>, <CODE>dcgettext</CODE>, <CODE>ngettext</CODE>,
<CODE>dngettext</CODE>, <CODE>dcngettext</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE> function
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function
<DT>setlocale
<DD>
Programmer must call <CODE>setlocale (LC_ALL, "")</CODE>
<DT>Prerequisite
<DD>
<CODE>#include "intl.h"</CODE>
<DT>Use or emulate GNU gettext
<DD>
Use
<DT>Extractor
<DD>
<CODE>xgettext -k_</CODE>
<DT>Formatting with positions
<DD>
---
<DT>Portability
<DD>
Uses autoconf macros
<DT>po-mode marking
<DD>
yes
</DL>
<H3><A NAME="SEC317" HREF="gettext_toc.html#TOC317">15.5.22 Lua</A></H3>
<DL COMPACT>
<DT>RPMs
<DD>
lua
<DT>File extension
<DD>
<CODE>lua</CODE>
<DT>String syntax
<DD>
<UL>
<LI><CODE>"abc"</CODE>
<LI><CODE>'abc'</CODE>
<LI><CODE>[[abc]]</CODE>
<LI><CODE>[=[abc]=]</CODE>
<LI><CODE>[==[abc]==]</CODE>
<LI>...
</UL>
<DT>gettext shorthand
<DD>
<CODE>_("abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>gettext.gettext</CODE>, <CODE>gettext.dgettext</CODE>, <CODE>gettext.dcgettext</CODE>,
<CODE>gettext.ngettext</CODE>, <CODE>gettext.dngettext</CODE>, <CODE>gettext.dcngettext</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE> function
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function
<DT>setlocale
<DD>
automatic
<DT>Prerequisite
<DD>
<CODE>require 'gettext'</CODE> or running lua interpreter with <CODE>-l gettext</CODE> option
<DT>Use or emulate GNU gettext
<DD>
use
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
---
<DT>Portability
<DD>
On platforms without gettext, the functions are not available.
<DT>po-mode marking
<DD>
---
</DL>
<H3><A NAME="SEC318" HREF="gettext_toc.html#TOC318">15.5.23 JavaScript</A></H3>
<DL COMPACT>
<DT>RPMs
<DD>
js
<DT>File extension
<DD>
<CODE>js</CODE>
<DT>String syntax
<DD>
<UL>
<LI><CODE>"abc"</CODE>
<LI><CODE>'abc'</CODE>
</UL>
<DT>gettext shorthand
<DD>
<CODE>_("abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>, <CODE>dgettext</CODE>, <CODE>dcgettext</CODE>, <CODE>ngettext</CODE>,
<CODE>dngettext</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE> function
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function
<DT>setlocale
<DD>
automatic
<DT>Prerequisite
<DD>
---
<DT>Use or emulate GNU gettext
<DD>
use, or emulate
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
---
<DT>Portability
<DD>
On platforms without gettext, the functions are not available.
<DT>po-mode marking
<DD>
---
</DL>
<H3><A NAME="SEC319" HREF="gettext_toc.html#TOC319">15.5.24 Vala</A></H3>
<DL COMPACT>
<DT>RPMs
<DD>
vala
<DT>File extension
<DD>
<CODE>vala</CODE>
<DT>String syntax
<DD>
<UL>
<LI><CODE>"abc"</CODE>
<LI><CODE>"""abc"""</CODE>
</UL>
<DT>gettext shorthand
<DD>
<CODE>_("abc")</CODE>
<DT>gettext/ngettext functions
<DD>
<CODE>gettext</CODE>, <CODE>dgettext</CODE>, <CODE>dcgettext</CODE>, <CODE>ngettext</CODE>,
<CODE>dngettext</CODE>, <CODE>dpgettext</CODE>, <CODE>dpgettext2</CODE>
<DT>textdomain
<DD>
<CODE>textdomain</CODE> function, defined under the <CODE>Intl</CODE> namespace
<DT>bindtextdomain
<DD>
<CODE>bindtextdomain</CODE> function, defined under the <CODE>Intl</CODE> namespace
<DT>setlocale
<DD>
Programmer must call <CODE>Intl.setlocale (LocaleCategory.ALL, "")</CODE>
<DT>Prerequisite
<DD>
---
<DT>Use or emulate GNU gettext
<DD>
Use
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
<DT>Formatting with positions
<DD>
Same as for the C language.
<DT>Portability
<DD>
autoconf (gettext.m4) and #if ENABLE_NLS
<DT>po-mode marking
<DD>
yes
</DL>
<H2><A NAME="SEC320" HREF="gettext_toc.html#TOC320">15.6 Internationalizable Data</A></H2>
<P>
Here is a list of other data formats which can be internationalized
using GNU gettext.
</P>
<H3><A NAME="SEC321" HREF="gettext_toc.html#TOC321">15.6.1 POT - Portable Object Template</A></H3>
<DL COMPACT>
<DT>RPMs
<DD>
gettext
<DT>File extension
<DD>
<CODE>pot</CODE>, <CODE>po</CODE>
<DT>Extractor
<DD>
<CODE>xgettext</CODE>
</DL>
<H3><A NAME="SEC322" HREF="gettext_toc.html#TOC322">15.6.2 Resource String Table</A></H3>
<P>
<A NAME="IDX1304"></A>
</P>
<DL COMPACT>
<DT>RPMs
<DD>
fpk
<DT>File extension
<DD>
<CODE>rst</CODE>
<DT>Extractor
<DD>
<CODE>xgettext</CODE>, <CODE>rstconv</CODE>
</DL>
<H3><A NAME="SEC323" HREF="gettext_toc.html#TOC323">15.6.3 Glade - GNOME user interface description</A></H3>
<DL COMPACT>
<DT>RPMs
<DD>
glade, libglade, glade2, libglade2, intltool
<DT>File extension
<DD>
<CODE>glade</CODE>, <CODE>glade2</CODE>, <CODE>ui</CODE>
<DT>Extractor
<DD>
<CODE>xgettext</CODE>, <CODE>libglade-xgettext</CODE>, <CODE>xml-i18n-extract</CODE>, <CODE>intltool-extract</CODE>
</DL>
<H3><A NAME="SEC324" HREF="gettext_toc.html#TOC324">15.6.4 GSettings - GNOME user configuration schema</A></H3>
<DL COMPACT>
<DT>RPMs
<DD>
glib2
<DT>File extension
<DD>
<CODE>gschema.xml</CODE>
<DT>Extractor
<DD>
<CODE>xgettext</CODE>, <CODE>intltool-extract</CODE>
</DL>
<H3><A NAME="SEC325" HREF="gettext_toc.html#TOC325">15.6.5 AppData - freedesktop.org application description</A></H3>
<DL COMPACT>
<DT>RPMs
<DD>
appdata-tools, appstream, libappstream-glib, libappstream-glib-builder
<DT>File extension
<DD>
<CODE>appdata.xml</CODE>
<DT>Extractor
<DD>
<CODE>xgettext</CODE>, <CODE>intltool-extract</CODE>, <CODE>itstool</CODE>
</DL>
<H3><A NAME="SEC326" HREF="gettext_toc.html#TOC326">15.6.6 Preparing Rules for XML Internationalization</A></H3>
<P>
<A NAME="IDX1305"></A>
</P>
<P>
Marking translatable strings in an XML file is done through a separate
"rule" file, making use of the Internationalization Tag Set standard
(ITS, <A HREF="http://www.w3.org/TR/its20/">http://www.w3.org/TR/its20/</A>). The currently supported ITS
data categories are: <SAMP>‘Translate’</SAMP>, <SAMP>‘Localization Note’</SAMP>,
<SAMP>‘Elements Within Text’</SAMP>, and <SAMP>‘Preserve Space’</SAMP>. In addition to
them, <CODE>xgettext</CODE> also recognizes the following extended data
categories:
</P>
<DL COMPACT>
<DT><SAMP>‘Context’</SAMP>
<DD>
This data category associates <CODE>msgctxt</CODE> to the extracted text. In
the global rule, the <CODE>contextRule</CODE> element contains the following:
<UL>
<LI>
A required <CODE>selector</CODE> attribute. It contains an absolute selector
that selects the nodes to which this rule applies.
<LI>
A required <CODE>contextPointer</CODE> attribute that contains a relative
selector pointing to a node that holds the <CODE>msgctxt</CODE> value.
<LI>
An optional <CODE>textPointer</CODE> attribute that contains a relative
selector pointing to a node that holds the <CODE>msgid</CODE> value.
</UL>
<DT><SAMP>‘Escape Special Characters’</SAMP>
<DD>
This data category indicates whether the special XML characters
(<CODE><</CODE>, <CODE>></CODE>, <CODE>&</CODE>, <CODE>"</CODE>) are escaped with entity
reference. In the global rule, the <CODE>escapeRule</CODE> element contains
the following:
<UL>
<LI>
A required <CODE>selector</CODE> attribute. It contains an absolute selector
that selects the nodes to which this rule applies.
<LI>
A required <CODE>escape</CODE> attribute with the value <CODE>yes</CODE> or <CODE>no</CODE>.
</UL>
<DT><SAMP>‘Extended Preserve Space’</SAMP>
<DD>
This data category extends the standard <SAMP>‘Preserve Space’</SAMP> data
category with the additional value <SAMP>‘trim’</SAMP>. The value means to
remove the leading and trailing whitespaces of the content, but not to
normalize whitespaces in the middle. In the global rule, the
<CODE>preserveSpaceRule</CODE> element contains the following:
<UL>
<LI>
A required <CODE>selector</CODE> attribute. It contains an absolute selector
that selects the nodes to which this rule applies.
<LI>
A required <CODE>space</CODE> attribute with the value <CODE>default</CODE>,
<CODE>preserve</CODE>, or <CODE>trim</CODE>.
</UL>
</DL>
<P>
All those extended data categories can only be expressed with global
rules, and the rule elements have to have the
<CODE>https://www.gnu.org/s/gettext/ns/its/extensions/1.0</CODE> namespace.
</P>
<P>
Given the following XML document in a file <TT>‘messages.xml’</TT>:
</P>
<PRE>
<?xml version="1.0"?>
<messages>
<message>
<p>A translatable string</p>
</message>
<message>
<p translatable="no">A non-translatable string</p>
</message>
</messages>
</PRE>
<P>
To extract the first text content ("A translatable string"), but not the
second ("A non-translatable string"), the following ITS rules can be used:
</P>
<PRE>
<?xml version="1.0"?>
<its:rules xmlns:its="http://www.w3.org/2005/11/its" version="1.0">
<its:translateRule selector="/messages" translate="no"/>
<its:translateRule selector="//message/p" translate="yes"/>
<!-- If 'p' has an attribute 'translatable' with the value 'no', then
the content is not translatable. -->
<its:translateRule selector="//message/p[@translatable = 'no']"
translate="no"/>
</its:rules>
</PRE>
<P>
<SAMP>‘xgettext’</SAMP> needs another file called "locating rule" to associate
an ITS rule with an XML file. If the above ITS file is saved as
<TT>‘messages.its’</TT>, the locating rule would look like:
</P>
<PRE>
<?xml version="1.0"?>
<locatingRules>
<locatingRule name="Messages" pattern="*.xml">
<documentRule localName="messages" target="messages.its"/>
</locatingRule>
<locatingRule name="Messages" pattern="*.msg" target="messages.its"/>
</locatingRules>
</PRE>
<P>
The <CODE>locatingRule</CODE> element must have a <CODE>pattern</CODE> attribute,
which denotes either a literal file name or a wildcard pattern of the
XML file<A NAME="DOCF7" HREF="gettext_foot.html#FOOT7">(7)</A>. The <CODE>locatingRule</CODE> element can have child
<CODE>documentRule</CODE> element, which adds checks on the content of the XML
file.
</P>
<P>
The first rule matches any file with the <TT>‘.xml’</TT> file extension, but
it only applies to XML files whose root element is <SAMP>‘<messages>’</SAMP>.
</P>
<P>
The second rule indicates that the same ITS rule file are also
applicable to any file with the <TT>‘.msg’</TT> file extension. The
optional <CODE>name</CODE> attribute of <CODE>locatingRule</CODE> allows to choose
rules by name, typically with <CODE>xgettext</CODE>'s <CODE>-L</CODE> option.
</P>
<P>
The associated ITS rule file is indicated by the <CODE>target</CODE> attribute
of <CODE>locatingRule</CODE> or <CODE>documentRule</CODE>. If it is specified in a
<CODE>documentRule</CODE> element, the parent <CODE>locatingRule</CODE> shouldn't
have the <CODE>target</CODE> attribute.
</P>
<P>
Locating rule files must have the <TT>‘.loc’</TT> file extension. Both ITS
rule files and locating rule files must be installed in the
<TT>‘$prefix/share/gettext/its’</TT> directory. Once those files are
properly installed, <CODE>xgettext</CODE> can extract translatable strings
from the matching XML files.
</P>
<H4><A NAME="SEC327" HREF="gettext_toc.html#TOC327">15.6.6.1 Two Use-cases of Translated Strings in XML</A></H4>
<P>
For XML, there are two use-cases of translated strings. One is the case
where the translated strings are directly consumed by programs, and the
other is the case where the translated strings are merged back to the
original XML document. In the former case, special characters in the
extracted strings shouldn't be escaped, while they should in the latter
case. To control wheter to escape special characters, the <SAMP>‘Escape
Special Characters’</SAMP> data category can be used.
</P>
<P>
To merge the translations, the <SAMP>‘msgfmt’</SAMP> program can be used with
the option <CODE>--xml</CODE>. See section <A HREF="gettext_10.html#SEC157">10.1 Invoking the <CODE>msgfmt</CODE> Program</A>, for more details
about how one calls the <SAMP>‘msgfmt’</SAMP> program. <SAMP>‘msgfmt’</SAMP>'s
<CODE>--xml</CODE> option doesn't perform character escaping, so translated
strings can have arbitrary XML constructs, such as elements for markup.
</P>
<P><HR><P>
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