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<FONT FACE="sans-serif" SIZE=-1><A HREF="http://www.zeegee.com" TARGET="_top"><IMG SRC="icons/zeegee.gif" ALT="ZeeGee Software" ALIGN="RIGHT" BORDER="0"></A><A NAME="__TOP__"><H1>IO::Scalar 2.104</H1>
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<P><B>This module is <FONT COLOR="#990000">BETA</FONT> code, which means that the interfaces are fairly stable BUT it has not been out in the community long enough to guarantee much testing. Use with caution! Please report any errors back to <A HREF="mailto:eryq@zeegee.com">eryq@zeegee.com</A> as soon as you can.</B><UL>
<LI> <A NAME="menu:NAME"><A HREF="#NAME">NAME</A></A>
<LI> <A NAME="menu:SYNOPSIS"><A HREF="#SYNOPSIS">SYNOPSIS</A></A>
<LI> <A NAME="menu:DESCRIPTION"><A HREF="#DESCRIPTION">DESCRIPTION</A></A>
<LI> <A NAME="menu:PUBLIC_INTERFACE"><A HREF="#PUBLIC_INTERFACE">PUBLIC INTERFACE</A></A>
<UL>
<LI> <A NAME="menu:Construction"><A HREF="#Construction">Construction</A></A>
<UL>
<LI> <A NAME="menu:item:new_ARGS"><A HREF="#item:new_ARGS">new [ARGS...]</A></A>
<LI> <A NAME="menu:item:open_SCALARREF"><A HREF="#item:open_SCALARREF">open [SCALARREF]</A></A>
<LI> <A NAME="menu:item:opened"><A HREF="#item:opened">opened</A></A>
<LI> <A NAME="menu:item:close"><A HREF="#item:close">close</A></A>
</UL>
<LI> <A NAME="menu:Input_and_output"><A HREF="#Input_and_output">Input and output</A></A>
<UL>
<LI> <A NAME="menu:item:flush"><A HREF="#item:flush">flush </A></A>
<LI> <A NAME="menu:item:getc"><A HREF="#item:getc">getc</A></A>
<LI> <A NAME="menu:item:getline"><A HREF="#item:getline">getline</A></A>
<LI> <A NAME="menu:item:getlines"><A HREF="#item:getlines">getlines</A></A>
<LI> <A NAME="menu:item:print_ARGS"><A HREF="#item:print_ARGS">print ARGS...</A></A>
<LI> <A NAME="menu:item:read_BUF_NBYTES_OFFSET"><A HREF="#item:read_BUF_NBYTES_OFFSET">read BUF, NBYTES, [OFFSET]</A></A>
<LI> <A NAME="menu:item:write_BUF_NBYTES_OFFSET"><A HREF="#item:write_BUF_NBYTES_OFFSET">write BUF, NBYTES, [OFFSET]</A></A>
<LI> <A NAME="menu:item:sysread_BUF_LEN_OFFSET"><A HREF="#item:sysread_BUF_LEN_OFFSET">sysread BUF, LEN, [OFFSET]</A></A>
<LI> <A NAME="menu:item:syswrite_BUF_NBYTES_OFFSET"><A HREF="#item:syswrite_BUF_NBYTES_OFFSET">syswrite BUF, NBYTES, [OFFSET]</A></A>
</UL>
<LI> <A NAME="menu:Seeking_telling_and_other_attributes"><A HREF="#Seeking_telling_and_other_attributes">Seeking/telling and other attributes</A></A>
<UL>
<LI> <A NAME="menu:item:autoflush"><A HREF="#item:autoflush">autoflush </A></A>
<LI> <A NAME="menu:item:binmode"><A HREF="#item:binmode">binmode</A></A>
<LI> <A NAME="menu:item:clearerr"><A HREF="#item:clearerr">clearerr</A></A>
<LI> <A NAME="menu:item:eof"><A HREF="#item:eof">eof </A></A>
<LI> <A NAME="menu:item:seek_OFFSET_WHENCE"><A HREF="#item:seek_OFFSET_WHENCE">seek OFFSET, WHENCE</A></A>
<LI> <A NAME="menu:item:sysseek_OFFSET_WHENCE"><A HREF="#item:sysseek_OFFSET_WHENCE">sysseek OFFSET, WHENCE</A></A>
<LI> <A NAME="menu:item:tell"><A HREF="#item:tell">tell</A></A>
<LI> <A NAME="menu:item:setpos_POS"><A HREF="#item:setpos_POS">setpos POS</A></A>
<LI> <A NAME="menu:item:getpos"><A HREF="#item:getpos">getpos </A></A>
<LI> <A NAME="menu:item:sref"><A HREF="#item:sref">sref</A></A>
</UL>
</UL>
<LI> <A NAME="menu:WARNINGS"><A HREF="#WARNINGS">WARNINGS</A></A>
<LI> <A NAME="menu:VERSION"><A HREF="#VERSION">VERSION</A></A>
<LI> <A NAME="menu:AUTHORS"><A HREF="#AUTHORS">AUTHORS</A></A>
<UL>
<LI> <A NAME="menu:Principal_author"><A HREF="#Principal_author">Principal author</A></A>
<LI> <A NAME="menu:Other_contributors"><A HREF="#Other_contributors">Other contributors</A></A>
</UL>
<LI> <A NAME="menu:SEE_ALSO"><A HREF="#SEE_ALSO">SEE ALSO</A></A>
</UL>
<P><HR>
<A NAME="NAME"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> NAME</H2></A>
<P>IO::Scalar - IO:: interface for reading/writing a scalar
<P><HR>
<A NAME="SYNOPSIS"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> SYNOPSIS</H2></A>
<P>Perform I/O on strings, using the basic OO interface...
<FONT SIZE=3 FACE="courier"><PRE>
use 5.005;
use IO::Scalar;
$data = "My message:\n";
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open a handle on a string, and append to it:
$SH = new IO::Scalar \$data;
$SH->print("Hello");
$SH->print(", world!\nBye now!\n");
print "The string is now: ", $data, "\n";
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open a handle on a string, read it line-by-line, then close it:
$SH = new IO::Scalar \$data;
while (defined($_ = $SH->getline)) {
print "Got line: $_";
}
$SH->close;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open a handle on a string, and slurp in all the lines:
$SH = new IO::Scalar \$data;
print "All lines:\n", $SH->getlines;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Get the current position (either of two ways):
$pos = $SH->getpos;
$offset = $SH->tell;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Set the current position (either of two ways):
$SH->setpos($pos);
$SH->seek($offset, 0);
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open an anonymous temporary scalar:
$SH = new IO::Scalar;
$SH->print("Hi there!");
print "I printed: ", ${$SH->sref}, "\n"; ### get at value
</PRE></FONT>
<P>Don't like OO for your I/O? No problem.
Thanks to the magic of an invisible tie(), the following now
works out of the box, just as it does with IO::Handle:
<FONT SIZE=3 FACE="courier"><PRE>
use 5.005;
use IO::Scalar;
$data = "My message:\n";
### Open a handle on a string, and append to it:
$SH = new IO::Scalar \$data;
print $SH "Hello";
print $SH ", world!\nBye now!\n";
print "The string is now: ", $data, "\n";
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open a handle on a string, read it line-by-line, then close it:
$SH = new IO::Scalar \$data;
while (<$SH>) {
print "Got line: $_";
}
close $SH;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open a handle on a string, and slurp in all the lines:
$SH = new IO::Scalar \$data;
print "All lines:\n", <$SH>;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Get the current position (WARNING: requires 5.6):
$offset = tell $SH;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Set the current position (WARNING: requires 5.6):
seek $SH, $offset, 0;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open an anonymous temporary scalar:
$SH = new IO::Scalar;
print $SH "Hi there!";
print "I printed: ", ${$SH->sref}, "\n"; ### get at value
</PRE></FONT>
<P>And for you folks with 1.x code out there: the old tie() style still works,
though this is <I>unnecessary and deprecated</I>:
<FONT SIZE=3 FACE="courier"><PRE>
use IO::Scalar;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Writing to a scalar...
my $s;
tie *OUT, 'IO::Scalar', \$s;
print OUT "line 1\nline 2\n", "line 3\n";
print "String is now: $s\n"
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Reading and writing an anonymous scalar...
tie *OUT, 'IO::Scalar';
print OUT "line 1\nline 2\n", "line 3\n";
tied(OUT)->seek(0,0);
while (<OUT>) {
print "Got line: ", $_;
}
</PRE></FONT>
<P>Stringification works, too!
<FONT SIZE=3 FACE="courier"><PRE>
my $SH = new IO::Scalar \$data;
print $SH "Hello, ";
print $SH "world!";
print "I printed: $SH\n";
</PRE></FONT>
<P><HR>
<A NAME="DESCRIPTION"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> DESCRIPTION</H2></A>
<P>This class is part of the IO::Stringy distribution;
see <A HREF="../IO/Stringy.pm.html">IO::Stringy</A> for change log and general information.
<P>The IO::Scalar class implements objects which behave just like
IO::Handle (or FileHandle) objects, except that you may use them
to write to (or read from) scalars. These handles are
automatically tiehandle'd (though please see <A HREF="#WARNINGS">WARNINGS</A>
for information relevant to your Perl version).
<P>Basically, this:
<FONT SIZE=3 FACE="courier"><PRE>
my $s;
$SH = new IO::Scalar \$s;
$SH->print("Hel", "lo, "); ### OO style
$SH->print("world!\n"); ### ditto
</PRE></FONT>
<P>Or this:
<FONT SIZE=3 FACE="courier"><PRE>
my $s;
$SH = tie *OUT, 'IO::Scalar', \$s;
print OUT "Hel", "lo, "; ### non-OO style
print OUT "world!\n"; ### ditto
</PRE></FONT>
<P>Causes $s to be set to:
<FONT SIZE=3 FACE="courier"><PRE>
"Hello, world!\n"
</PRE></FONT>
<P><HR>
<A NAME="PUBLIC_INTERFACE"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> PUBLIC INTERFACE</H2></A>
<P><HR>
<A NAME="Construction"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Construction</H3></A>
<DL>
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:new"><A NAME="item:new_ARGS">new [ARGS...]</A></A></B></DT>
<DD>
<I>Class method.</I>
Return a new, unattached scalar handle.
If any arguments are given, they're sent to open().
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:open"><A NAME="item:open_SCALARREF">open [SCALARREF]</A></A></B></DT>
<DD>
<I>Instance method.</I>
Open the scalar handle on a new scalar, pointed to by SCALARREF.
If no SCALARREF is given, a "private" scalar is created to hold
the file data.
<P>Returns the self object on success, undefined on error.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:opened">opened</A></B></DT>
<DD>
<I>Instance method.</I>
Is the scalar handle opened on something?
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:close">close</A></B></DT>
<DD>
<I>Instance method.</I>
Disassociate the scalar handle from its underlying scalar.
Done automatically on destroy.
</DL>
<P><HR>
<A NAME="Input_and_output"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Input and output</H3></A>
<DL>
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:flush">flush</A></B></DT>
<DD>
<I>Instance method.</I>
No-op, provided for OO compatibility.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:getc">getc</A></B></DT>
<DD>
<I>Instance method.</I>
Return the next character, or undef if none remain.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:getline">getline</A></B></DT>
<DD>
<I>Instance method.</I>
Return the next line, or undef on end of string.
Can safely be called in an array context.
Currently, lines are delimited by "\n".
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:getlines">getlines</A></B></DT>
<DD>
<I>Instance method.</I>
Get all remaining lines.
It will croak() if accidentally called in a scalar context.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:print"><A NAME="item:print_ARGS">print ARGS...</A></A></B></DT>
<DD>
<I>Instance method.</I>
Print ARGS to the underlying scalar.
<P><B>Warning:</B> this continues to always cause a seek to the end
of the string, but if you perform seek()s and tell()s, it is
still safer to explicitly seek-to-end before subsequent print()s.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:read"><A NAME="item:read_BUF_NBYTES_OFFSET">read BUF, NBYTES, [OFFSET]</A></A></B></DT>
<DD>
<I>Instance method.</I>
Read some bytes from the scalar.
Returns the number of bytes actually read, 0 on end-of-file, undef on error.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:write"><A NAME="item:write_BUF_NBYTES_OFFSET">write BUF, NBYTES, [OFFSET]</A></A></B></DT>
<DD>
<I>Instance method.</I>
Write some bytes to the scalar.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:sysread"><A NAME="item:sysread_BUF_LEN_OFFSET">sysread BUF, LEN, [OFFSET]</A></A></B></DT>
<DD>
<I>Instance method.</I>
Read some bytes from the scalar.
Returns the number of bytes actually read, 0 on end-of-file, undef on error.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:syswrite"><A NAME="item:syswrite_BUF_NBYTES_OFFSET">syswrite BUF, NBYTES, [OFFSET]</A></A></B></DT>
<DD>
<I>Instance method.</I>
Write some bytes to the scalar.
</DL>
<P><HR>
<A NAME="Seeking_telling_and_other_attributes"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Seeking/telling and other attributes</H3></A>
<DL>
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:autoflush">autoflush</A></B></DT>
<DD>
<I>Instance method.</I>
No-op, provided for OO compatibility.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:binmode">binmode</A></B></DT>
<DD>
<I>Instance method.</I>
No-op, provided for OO compatibility.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:clearerr">clearerr</A></B></DT>
<DD>
<I>Instance method.</I> Clear the error and EOF flags. A no-op.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:eof">eof</A></B></DT>
<DD>
<I>Instance method.</I> Are we at end of file?
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:seek"><A NAME="item:seek_OFFSET_WHENCE">seek OFFSET, WHENCE</A></A></B></DT>
<DD>
<I>Instance method.</I> Seek to a given position in the stream.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:sysseek"><A NAME="item:sysseek_OFFSET_WHENCE">sysseek OFFSET, WHENCE</A></A></B></DT>
<DD>
<I>Instance method.</I> Identical to <CODE>seek OFFSET, WHENCE</CODE>, <I>q.v.</I>
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:tell">tell</A></B></DT>
<DD>
<I>Instance method.</I>
Return the current position in the stream, as a numeric offset.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:setpos"><A NAME="item:setpos_POS">setpos POS</A></A></B></DT>
<DD>
<I>Instance method.</I>
Set the current position, using the opaque value returned by <CODE>getpos()</CODE>.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:getpos">getpos</A></B></DT>
<DD>
<I>Instance method.</I>
Return the current position in the string, as an opaque object.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:sref">sref</A></B></DT>
<DD>
<I>Instance method.</I>
Return a reference to the underlying scalar.
</DL>
<P><HR>
<A NAME="WARNINGS"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> WARNINGS</H2></A>
<P>Perl's TIEHANDLE spec was incomplete prior to 5.005_57;
it was missing support for <CODE>seek()</CODE>, <CODE>tell()</CODE>, and <CODE>eof()</CODE>.
Attempting to use these functions with an IO::Scalar will not work
prior to 5.005_57. IO::Scalar will not have the relevant methods
invoked; and even worse, this kind of bug can lie dormant for a while.
If you turn warnings on (via <CODE>$^W</CODE> or <CODE>perl -w</CODE>),
and you see something like this...
<FONT SIZE=3 FACE="courier"><PRE>
attempt to seek on unopened filehandle
</PRE></FONT>
<P>...then you are probably trying to use one of these functions
on an IO::Scalar with an old Perl. The remedy is to simply
use the OO version; e.g.:
<FONT SIZE=3 FACE="courier"><PRE>
$SH->seek(0,0); ### GOOD: will work on any 5.005
seek($SH,0,0); ### WARNING: will only work on 5.005_57 and beyond
</PRE></FONT>
<P><HR>
<A NAME="VERSION"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> VERSION</H2></A>
<P>$Id: Scalar.pm,v 2.104 2001/08/09 08:04:44 eryq Exp $
<P><HR>
<A NAME="AUTHORS"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> AUTHORS</H2></A>
<P><HR>
<A NAME="Principal_author"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Principal author</H3></A>
<P>Eryq (<I><FILE><A HREF="mailto:eryq@zeegee.com">eryq@zeegee.com</A></FILE></I>).
President, ZeeGee Software Inc (<I><FILE><A HREF="http://www.zeegee.com">http://www.zeegee.com</A></FILE></I>).
<P><HR>
<A NAME="Other_contributors"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Other contributors</H3></A>
<P>The full set of contributors always includes the folks mentioned
in <A HREF="../IO/Stringy.pm.html#CHANGE_LOG">CHANGE LOG</A>. But just the same, special
thanks to the following individuals for their invaluable contributions
(if I've forgotten or misspelled your name, please email me!):
<P><I>Andy Glew,</I>
for contributing <CODE>getc()</CODE>.
<P><I>Brandon Browning,</I>
for suggesting <CODE>opened()</CODE>.
<P><I>David Richter,</I>
for finding and fixing the bug in <CODE>PRINTF()</CODE>.
<P><I>Eric L. Brine,</I>
for his offset-using read() and write() implementations.
<P><I>Richard Jones,</I>
for his patches to massively improve the performance of <CODE>getline()</CODE>
and add <CODE>sysread</CODE> and <CODE>syswrite</CODE>.
<P><I>B. K. Oxley (binkley),</I>
for stringification and inheritance improvements,
and sundry good ideas.
<P><I>Doug Wilson,</I>
for the IO::Handle inheritance and automatic tie-ing.
<P><HR>
<A NAME="SEE_ALSO"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> SEE ALSO</H2></A>
<P><A HREF="../IO/String.pm.html">IO::String</A>, which is quite similar but which was designed
more-recently and with an IO::Handle-like interface in mind,
so you could mix OO- and native-filehandle usage without using tied().
<P><I>Note:</I> as of version 2.x, these classes all work like
their IO::Handle counterparts, so we have comparable
functionality to IO::String.
<P><HR>
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