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<link title="Getopt" rel="Chapter" href="Getopt.html"><link title="Layout of the command line" rel="Section" href="#1_Layoutofthecommandline">
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<center><h1>Module <a href="type_Getopt.html">Getopt</a></h1></center>
<br>
<pre><span class="keyword">module</span> Getopt: <code class="code">sig</code> <a href="Getopt.html">..</a> <code class="code">end</code></pre>Module <code class="code">Getopt</code>: parsing of command line arguments.
<p>
Copyright (C) 2000-2004 Alain Frisch. Distributed under the terms of the MIT
license.
<p>
email: <a href="Alain.Frisch@ens.fr">Alain Frisch@ens.fr</a>
<p>
web: <a href="http://www.eleves.ens.fr/home/frisch">http://www.eleves.ens.fr/home/frisch</a>
<p>
This module provides a general mechanism for extracting options and
arguments from the command line to the program. It is an alternative
to the module <code class="code">Arg</code> from the standard OCaml distribution.
<p>
The syntax is close to GNU getopt and getop_long (<code class="code">man 3 getopt</code>).<br>
<hr width="100%">
<br>
<a name="1_Layoutofthecommandline"></a>
<h1>Layout of the command line</h1>
There are two types of argument on the command line: options and
anonymous arguments. Options may have two forms: a short one introduced
by a single dash character (-) and a long one introduced by a double
dash (--).
<p>
Options may have an argument attached. For the long form, the syntax
is "--option=argument". For the short form, there are two possible syntaxes:
"-o argument" (argument doesn't start with a dash) and "-oargument"
<p>
Short options that refuse arguments may be concatenated, as in
"-opq".
<p>
The special argument -- interrupts the parsing of options: all the
remaining arguments are arguments even they start with a dash.
<p>
<a name="1_Commandlinespecification"></a>
<h1>Command line specification</h1>
A specification lists the possible options and describe what to do
when they are found; it also gives the action for anonymous arguments
and for the special option - (a single dash alone).<br>
<pre><span class="keyword">type</span> <a name="TYPEopt"></a><code class="type"></code>opt = <code class="type">char * string * (unit -> unit) option * (string -> unit) option</code> </pre>
<br>
The specification for a single option is a tuple
<code class="code">(short_form, long_form, action, handler)</code>
where:<ul>
<li><code class="code">short_form</code> is the character for the short form of the option
without the leading -
(or <code class="code">noshort='\000'</code> if the option does not have a short form)</li>
</ul>
<ul>
<li><code class="code">long_form</code> is the string for the long form of the option
without the leading --
(or <code class="code">nolong=""</code> if no long form)</li>
</ul>
<ul>
<li><code class="code">(action : (unit -> unit) option)</code> gives the action to be executed
when the option is found without an argument</li>
</ul>
<ul>
<li><code class="code">(handler : (string -> unit) option)</code> specifies how to handle the
argument when the option is found with the argument</li>
</ul>
According to the pair <code class="code">(action, handler)</code>, the corresponding option
may, must or mustn't have an argument :
<p>
<ul>
<li><code class="code">(Some _, Some _)</code> : the option may have an argument; the short form can't be
concatenated with other options (even if the user does not want to provide
an argument). The behaviour (handler/action) is determined by the
presence of the argument.</li>
</ul>
<ul>
<li><code class="code">(Some _, None)</code> : the option must not have an argument; the short form, if
it exists, may be concatenated</li>
</ul>
<ul>
<li><code class="code">(None, Some _)</code> : the option must have an argument; the short form can't
be concatenated</li>
</ul>
<ul>
<li><code class="code">(None, None)</code> : not allowed</li>
</ul>
<br>
<pre><span class="keyword">val</span> <a name="VALnoshort"></a>noshort : <code class="type">char</code></pre><div class="info">
<code class="code">noshort='\000'</code> can be used when an option has no short form<br>
</div>
<pre><span class="keyword">val</span> <a name="VALnolong"></a>nolong : <code class="type">string</code></pre><div class="info">
<code class="code">nolong=""</code> can be used when an option has no long form<br>
</div>
<pre><span class="keyword">exception</span> <a name="EXCEPTIONError"></a>Error <span class="keyword">of</span> <code class="type">string</code></pre>
<div class="info">
Signals error on the command line<br>
</div>
<br>
<a name="1_Parsingthecommandline"></a>
<h1>Parsing the command line</h1><br>
<pre><span class="keyword">val</span> <a name="VALparse"></a>parse : <code class="type"><a href="Getopt.html#TYPEopt">opt</a> list -> (string -> unit) -> string array -> int -> int -> unit</code></pre><div class="info">
<code class="code">parse opts others args first last</code> parse the arguments
<code class="code">args.(first)</code>, <code class="code">arg.(first+1)</code> ... <code class="code">args.(last)</code>.
<code class="code">others</code> is called on anonymous arguments (and the special - argument);
<code class="code">opts</code> is a list of option specifications (there must be no ambiguities).<br>
<b>Raises</b> <code>Error</code> : Unknown options, unexpected argument, ...<br>
</div>
<pre><span class="keyword">val</span> <a name="VALparse_cmdline"></a>parse_cmdline : <code class="type"><a href="Getopt.html#TYPEopt">opt</a> list -> (string -> unit) -> unit</code></pre><div class="info">
Parse the command line in <code class="code">Sys.argv</code> using <code class="code">parse</code>.<br>
</div>
<br>
<a name="1_Usefulactionsandhandlers"></a>
<h1>Useful actions and handlers</h1><br>
<pre><span class="keyword">val</span> <a name="VALset"></a>set : <code class="type">'a Pervasives.ref -> 'a -> (unit -> unit) option</code></pre><div class="info">
<b>Returns</b> an action that gives a reference a given value<br>
</div>
<pre><span class="keyword">val</span> <a name="VALincr"></a>incr : <code class="type">int Pervasives.ref -> (unit -> unit) option</code></pre><div class="info">
<b>Returns</b> an action that increments an <code class="code">int</code> reference<br>
</div>
<pre><span class="keyword">val</span> <a name="VALappend"></a>append : <code class="type">string list Pervasives.ref -> (string -> unit) option</code></pre><div class="info">
<b>Returns</b> an handler that appends the argument to the end of a <code class="code">string list</code>
reference<br>
</div>
<pre><span class="keyword">val</span> <a name="VALatmost_once"></a>atmost_once : <code class="type">string Pervasives.ref -> exn -> (string -> unit) option</code></pre><div class="info">
<b>Returns</b> an handler that stores the argument in a <code class="code">string</code> reference if
it is empty, raises an exception otherwise<br>
</div>
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