133 lines
5.7 KiB
HTML
133 lines
5.7 KiB
HTML
<!DOCTYPE html>
|
|
<html>
|
|
<!-- Created by GNU Texinfo 7.1, https://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<!-- This manual documents Guile version 3.0.10.
|
|
|
|
Copyright (C) 1996-1997, 2000-2005, 2009-2023 Free Software Foundation,
|
|
Inc.
|
|
|
|
Copyright (C) 2021 Maxime Devos
|
|
|
|
Copyright (C) 2024 Tomas Volf
|
|
|
|
|
|
Permission is granted to copy, distribute and/or modify this document
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
|
any later version published by the Free Software Foundation; with no
|
|
Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
|
|
copy of the license is included in the section entitled "GNU Free
|
|
Documentation License." -->
|
|
<title>getopt-long Example (Guile Reference Manual)</title>
|
|
|
|
<meta name="description" content="getopt-long Example (Guile Reference Manual)">
|
|
<meta name="keywords" content="getopt-long Example (Guile Reference Manual)">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content=".texi2any-real">
|
|
<meta name="viewport" content="width=device-width,initial-scale=1">
|
|
|
|
<link href="index.html" rel="start" title="Top">
|
|
<link href="Concept-Index.html" rel="index" title="Concept Index">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="getopt_002dlong.html" rel="up" title="getopt-long">
|
|
<link href="Option-Specification.html" rel="next" title="Option Specification">
|
|
<style type="text/css">
|
|
<!--
|
|
a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em}
|
|
div.example {margin-left: 3.2em}
|
|
span:hover a.copiable-link {visibility: visible}
|
|
-->
|
|
</style>
|
|
<link rel="stylesheet" type="text/css" href="https://www.gnu.org/software/gnulib/manual.css">
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en">
|
|
<div class="subsection-level-extent" id="getopt_002dlong-Example">
|
|
<div class="nav-panel">
|
|
<p>
|
|
Next: <a href="Option-Specification.html" accesskey="n" rel="next">How to Write an Option Specification</a>, Up: <a href="getopt_002dlong.html" accesskey="u" rel="up">The (ice-9 getopt-long) Module</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<h4 class="subsection" id="A-Short-getopt_002dlong-Example"><span>7.4.1 A Short getopt-long Example<a class="copiable-link" href="#A-Short-getopt_002dlong-Example"> ¶</a></span></h4>
|
|
|
|
<p>This section illustrates how <code class="code">getopt-long</code> is used by presenting
|
|
and dissecting a simple example. The first thing that we need is an
|
|
<em class="dfn">option specification</em> that tells <code class="code">getopt-long</code> how to parse
|
|
the command line. This specification is an association list with the
|
|
long option name as the key. Here is how such a specification might
|
|
look:
|
|
</p>
|
|
<div class="example lisp">
|
|
<pre class="lisp-preformatted">(define option-spec
|
|
'((version (single-char #\v) (value #f))
|
|
(help (single-char #\h) (value #f))))
|
|
</pre></div>
|
|
|
|
<p>This alist tells <code class="code">getopt-long</code> that it should accept two long
|
|
options, called <em class="emph">version</em> and <em class="emph">help</em>, and that these options
|
|
can also be selected by the single-letter abbreviations <em class="emph">v</em> and
|
|
<em class="emph">h</em>, respectively. The <code class="code">(value #f)</code> clauses indicate that
|
|
neither of the options accepts a value.
|
|
</p>
|
|
<p>With this specification we can use <code class="code">getopt-long</code> to parse a given
|
|
command line:
|
|
</p>
|
|
<div class="example lisp">
|
|
<pre class="lisp-preformatted">(define options (getopt-long (command-line) option-spec))
|
|
</pre></div>
|
|
|
|
<p>After this call, <code class="code">options</code> contains the parsed command line and is
|
|
ready to be examined by <code class="code">option-ref</code>. <code class="code">option-ref</code> is called
|
|
like this:
|
|
</p>
|
|
<div class="example lisp">
|
|
<pre class="lisp-preformatted">(option-ref options 'help #f)
|
|
</pre></div>
|
|
|
|
<p>It expects the parsed command line, a symbol indicating the option to
|
|
examine, and a default value. The default value is returned if the
|
|
option was not present in the command line, or if the option was present
|
|
but without a value; otherwise the value from the command line is
|
|
returned. Usually <code class="code">option-ref</code> is called once for each possible
|
|
option that a script supports.
|
|
</p>
|
|
<p>The following example shows a main program which puts all this together
|
|
to parse its command line and figure out what the user wanted.
|
|
</p>
|
|
<div class="example lisp">
|
|
<pre class="lisp-preformatted">(define (main args)
|
|
(let* ((option-spec '((version (single-char #\v) (value #f))
|
|
(help (single-char #\h) (value #f))))
|
|
(options (getopt-long args option-spec))
|
|
(help-wanted (option-ref options 'help #f))
|
|
(version-wanted (option-ref options 'version #f)))
|
|
(if (or version-wanted help-wanted)
|
|
(begin
|
|
(if version-wanted
|
|
(display "getopt-long-example version 0.3\n"))
|
|
(if help-wanted
|
|
(display "\
|
|
getopt-long-example [options]
|
|
-v, --version Display version
|
|
-h, --help Display this help
|
|
")))
|
|
(begin
|
|
(display "Hello, World!") (newline)))))
|
|
</pre></div>
|
|
|
|
|
|
</div>
|
|
<hr>
|
|
<div class="nav-panel">
|
|
<p>
|
|
Next: <a href="Option-Specification.html">How to Write an Option Specification</a>, Up: <a href="getopt_002dlong.html">The (ice-9 getopt-long) Module</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|