<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>ext:process-command-args</title><link rel="stylesheet" href="ecl.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.75.2"><link rel="home" href="index.html" title="The ECL manual"><link rel="up" href="ch17s03.html" title="2.3. OS Reference"><link rel="prev" href="re08.html" title="ext:command-args"><link rel="next" href="re10.html" title="ext:quit"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><code class="function">ext:process-command-args</code></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re08.html">Prev</a> </td><th width="60%" align="center">2.3. OS Reference</th><td width="20%" align="right"> <a accesskey="n" href="re10.html">Next</a></td></tr></table><hr></div><div class="refentry" title="ext:process-command-args"><a name="ref.process-command-args"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p><code class="function">ext:process-command-args</code> — Process command line arguments.</p></div><div class="refsynopsisdiv" title="Function"><h2>Function</h2><div class="funcsynopsis"><p><code class="funcdef">(ext:process-command-args</code> <var class="pdparam">&key</var>) ⇒ <var class="pdparam">args</var>) ⇒ <var class="pdparam">rules</var>)</p></div><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><p><span class="term"><em class="replaceable"><code>args</code></em></span></p></td><td><p>A list of strings. Defaults to the output of <a class="xref" href="re08.html" title="ext:command-args"><code class="function">ext:command-args</code></a></p></td></tr><tr><td><p><span class="term"><em class="replaceable"><code>rules</code></em></span></p></td><td><p>A list of lists. Defaults to the value of <a class="xref" href="re07.html" title="ext:+default-command-arg-rules+"><code class="varname">ext:+default-command-arg-rules+</code></a></p></td></tr></tbody></table></div></div><div class="refsect1" title="Description"><a name="id654120"></a><h2>Description</h2><p>This function processes the command line arguments passed to either
<span class="application">ECL</span> or the program that embeds it. It uses the list of rules
<em class="replaceable"><code>rules</code></em>, which has the following syntax:
</p><pre class="synopsis">(option-name nargs template [:stop | :noloadrc | :loadrc]*)</pre><p>
</p><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><p><span class="term"><em class="replaceable"><code>option-name</code></em></span></p></td><td><p>A string with the option prefix as typed by the user. For
instance <code class="option">--help</code>, <code class="option">-?</code>,
<code class="option">--compile</code>, etc.</p></td></tr><tr><td><p><span class="term"><em class="replaceable"><code>nargs</code></em></span></p></td><td><p>A nonnegative integer denoting the number of arguments
taken by this option.</p></td></tr><tr><td><p><span class="term"><em class="replaceable"><code>template</code></em></span></p></td><td><p>A lisp form, not evaluated, where numbers from 0 to
<em class="replaceable"><code>nargs</code></em> will be replaced by the corresponding
option argument.</p></td></tr><tr><td><p><span class="term"><span class="symbol">:STOP</span></span></p></td><td><p>If present, parsing of arguments stops after this option
is found and processed.</p></td></tr><tr><td><p><span class="term"><span class="symbol">:NOLOADRC</span> and <span class="symbol">:LOADRC</span></span></p></td><td><p>Determine whether the lisp initalization file (<a class="xref" href="re06.html" title="ext:*lisp-init-file-list*"><code class="varname">ext:*lisp-init-file-list*</code></a>) will be loaded before processing
all forms.</p></td></tr></tbody></table></div><p><code class="function">EXT:PROCESS-COMMAND-ARGS</code> works as follows. First
of all, it parses all the command line arguments, except for the first one,
which is assumed to contain the program name. Each of these arguments is
matched against the rules, sequentially, until one of the patterns
succeeeds.</p><p>A special name <code class="literal">"*DEFAULT*"</code>, matches any unknown
command line option. This template gets a single argument, which is the list
of remaining unprocessed options.</p><p>If no match is found, an error is signalled. For each rule
that succeeds, the function constructs a lisp statement using the
<em class="replaceable"><code>template</code></em>.</p><p>After all arguments have been processed,
<code class="function">EXT:PROCESS-COMMAND-ARGS</code>, and there were no occurences
of <span class="symbol">:NOLOADRC</span>, one of the files listed in <a class="xref" href="re06.html" title="ext:*lisp-init-file-list*"><code class="varname">ext:*lisp-init-file-list*</code></a> will be loaded. Finally, the list of
lisp statements will be evaluated.</p></div><div class="refsect1" title="Example"><a name="id654273"></a><h2>Example</h2><p>The following piece of code implements the <span class="command"><strong>ls</strong></span>
command using lisp.<sup>[<a name="id654286" href="#ftn.id654286" class="footnote">2</a>]</sup></p><pre class="programlisting">
(setq ext:*help-message* "
ls [--help | -?] filename*
Lists the file that match the given patterns.
")
(defun print-directory (pathnames)
(format t "~{~A~%~}"
(mapcar #'(lambda (x) (enough-namestring x (si::getcwd)))
(mapcan #'directory (or pathnames '("*.*" "*/"))))))
(defconstant +ls-rules+
'(("--help" 0 (progn (princ ext:*help-message* *standard-output*) (ext:quit 0)))
("-?" 0 (progn (princ ext:*help-message* *standard-output*) (ext:quit 0)))
("*DEFAULT*" 1 (print-directory 1))))
(let ((ext:*lisp-init-file-list* NIL)) ; No initialization files
(handler-case (ext:process-command-args :rules +ls-rules+)
(error (c)
(princ ext:*help-message* *error-output*)
(ext:quit 1))))
(ext:quit 0)
</pre></div><div class="footnotes"><br><hr width="100" align="left"><div class="footnote"><p><sup>[<a name="ftn.id654286" href="#id654286" class="para">2</a>] </sup>Instructions for building this program
are found under
<code class="filename">ecl/examples/cmdline/ls.lsp</code></p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re08.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch17s03.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re10.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><code class="function">ext:command-args</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <code class="function">ext:quit</code></td></tr></table></div></body></html>
