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<center><h1>Module <a href="type_Arg.html">Arg</a></h1></center>
<br>
<pre><span class="keyword">module</span> Arg: <code class="code"><span class="keyword">sig</span></code> <a href="Arg.html">..</a> <code class="code"><span class="keyword">end</span></code></pre>Parsing of command line arguments.
<p>
This module provides a general mechanism for extracting options and
arguments from the command line to the program.
<p>
Syntax of command lines:
A keyword is a character string starting with a <code class="code">-</code>.
An option is a keyword alone or followed by an argument.
The types of keywords are: <code class="code"><span class="constructor">Unit</span></code>, <code class="code"><span class="constructor">Bool</span></code>, <code class="code"><span class="constructor">Set</span></code>, <code class="code"><span class="constructor">Clear</span></code>,
<code class="code"><span class="constructor">String</span></code>, <code class="code"><span class="constructor">Set_string</span></code>, <code class="code"><span class="constructor">Int</span></code>, <code class="code"><span class="constructor">Set_int</span></code>, <code class="code"><span class="constructor">Float</span></code>, <code class="code"><span class="constructor">Set_float</span></code>,
<code class="code"><span class="constructor">Tuple</span></code>, <code class="code"><span class="constructor">Symbol</span></code>, and <code class="code"><span class="constructor">Rest</span></code>.
<code class="code"><span class="constructor">Unit</span></code>, <code class="code"><span class="constructor">Set</span></code> and <code class="code"><span class="constructor">Clear</span></code> keywords take no argument. A <code class="code"><span class="constructor">Rest</span></code>
keyword takes the remaining of the command line as arguments.
Every other keyword takes the following word on the command line
as argument.
Arguments not preceded by a keyword are called anonymous arguments.
<p>
Examples (<code class="code">cmd</code> is assumed to be the command name):<ul>
<li> <code class="code">cmd -flag </code>(a unit option)</li>
<li> <code class="code">cmd -int 1 </code>(an int option with argument <code class="code">1</code>)</li>
<li> <code class="code">cmd -string foobar </code>(a string option with argument <code class="code"><span class="string">"foobar"</span></code>)</li>
<li> <code class="code">cmd -float 12.34 </code>(a float option with argument <code class="code">12.34</code>)</li>
<li> <code class="code">cmd a b c </code>(three anonymous arguments: <code class="code"><span class="string">"a"</span></code>, <code class="code"><span class="string">"b"</span></code>, and <code class="code"><span class="string">"c"</span></code>)</li>
<li> <code class="code">cmd a b -- c d </code>(two anonymous arguments and a rest option with
two arguments)</li>
</ul>
<br>
<hr width="100%">
<br><code><span class="keyword">type</span> <a name="TYPEspec"></a><code class="type"></code>spec = </code><table class="typetable">
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Unit</span> <span class="keyword">of</span> <code class="type">(unit -> unit)</code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Call the function with unit argument</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Bool</span> <span class="keyword">of</span> <code class="type">(bool -> unit)</code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Call the function with a bool argument</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Set</span> <span class="keyword">of</span> <code class="type">bool <a href="Pervasives.html#TYPEref">ref</a></code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Set the reference to true</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Clear</span> <span class="keyword">of</span> <code class="type">bool <a href="Pervasives.html#TYPEref">ref</a></code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Set the reference to false</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">String</span> <span class="keyword">of</span> <code class="type">(string -> unit)</code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Call the function with a string argument</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Set_string</span> <span class="keyword">of</span> <code class="type">string <a href="Pervasives.html#TYPEref">ref</a></code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Set the reference to the string argument</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Int</span> <span class="keyword">of</span> <code class="type">(int -> unit)</code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Call the function with an int argument</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Set_int</span> <span class="keyword">of</span> <code class="type">int <a href="Pervasives.html#TYPEref">ref</a></code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Set the reference to the int argument</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Float</span> <span class="keyword">of</span> <code class="type">(float -> unit)</code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Call the function with a float argument</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Set_float</span> <span class="keyword">of</span> <code class="type">float <a href="Pervasives.html#TYPEref">ref</a></code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Set the reference to the float argument</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Tuple</span> <span class="keyword">of</span> <code class="type"><a href="Arg.html#TYPEspec">spec</a> list</code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Take several arguments according to the
spec list</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Symbol</span> <span class="keyword">of</span> <code class="type">string list * (string -> unit)</code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Take one of the symbols as argument and
call the function with the symbol</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Rest</span> <span class="keyword">of</span> <code class="type">(string -> unit)</code></code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" >Stop interpreting keywords and call the
function with each remaining argument</td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr></table>
<div class="info">
The concrete type describing the behavior associated
with a keyword.<br>
</div>
<pre><span class="keyword">type</span> <a name="TYPEkey"></a><code class="type"></code>key = <code class="type">string</code> </pre>
<pre><span class="keyword">type</span> <a name="TYPEdoc"></a><code class="type"></code>doc = <code class="type">string</code> </pre>
<pre><span class="keyword">type</span> <a name="TYPEusage_msg"></a><code class="type"></code>usage_msg = <code class="type">string</code> </pre>
<pre><span class="keyword">type</span> <a name="TYPEanon_fun"></a><code class="type"></code>anon_fun = <code class="type">string -> unit</code> </pre>
<pre><span class="keyword">val</span> <a name="VALparse"></a>parse : <code class="type">(<a href="Arg.html#TYPEkey">key</a> * <a href="Arg.html#TYPEspec">spec</a> * <a href="Arg.html#TYPEdoc">doc</a>) list -> <a href="Arg.html#TYPEanon_fun">anon_fun</a> -> <a href="Arg.html#TYPEusage_msg">usage_msg</a> -> unit</code></pre><div class="info">
<code class="code"><span class="constructor">Arg</span>.parse speclist anon_fun usage_msg</code> parses the command line.
<code class="code">speclist</code> is a list of triples <code class="code">(key, spec, doc)</code>.
<code class="code">key</code> is the option keyword, it must start with a <code class="code"><span class="string">'-'</span></code> character.
<code class="code">spec</code> gives the option type and the function to call when this option
is found on the command line.
<code class="code">doc</code> is a one-line description of this option.
<code class="code">anon_fun</code> is called on anonymous arguments.
The functions in <code class="code">spec</code> and <code class="code">anon_fun</code> are called in the same order
as their arguments appear on the command line.
<p>
If an error occurs, <code class="code"><span class="constructor">Arg</span>.parse</code> exits the program, after printing
an error message as follows:<ul>
<li> The reason for the error: unknown option, invalid or missing argument, etc.</li>
<li> <code class="code">usage_msg</code></li>
<li> The list of options, each followed by the corresponding <code class="code">doc</code> string.</li>
</ul>
For the user to be able to specify anonymous arguments starting with a
<code class="code">-</code>, include for example <code class="code">(<span class="string">"-"</span>, <span class="constructor">String</span> anon_fun, doc)</code> in <code class="code">speclist</code>.
<p>
By default, <code class="code">parse</code> recognizes two unit options, <code class="code">-help</code> and <code class="code">--help</code>,
which will display <code class="code">usage_msg</code> and the list of options, and exit
the program. You can override this behaviour by specifying your
own <code class="code">-help</code> and <code class="code">--help</code> options in <code class="code">speclist</code>.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALparse_argv"></a>parse_argv : <code class="type">?current:int <a href="Pervasives.html#TYPEref">ref</a> -><br> string array -><br> (<a href="Arg.html#TYPEkey">key</a> * <a href="Arg.html#TYPEspec">spec</a> * <a href="Arg.html#TYPEdoc">doc</a>) list -> <a href="Arg.html#TYPEanon_fun">anon_fun</a> -> <a href="Arg.html#TYPEusage_msg">usage_msg</a> -> unit</code></pre><div class="info">
<code class="code"><span class="constructor">Arg</span>.parse_argv ~current args speclist anon_fun usage_msg</code> parses
the array <code class="code">args</code> as if it were the command line. It uses and updates
the value of <code class="code">~current</code> (if given), or <code class="code"><span class="constructor">Arg</span>.current</code>. You must set
it before calling <code class="code">parse_argv</code>. The initial value of <code class="code">current</code>
is the index of the program name (argument 0) in the array.
If an error occurs, <code class="code"><span class="constructor">Arg</span>.parse_argv</code> raises <code class="code"><span class="constructor">Arg</span>.<span class="constructor">Bad</span></code> with
the error message as argument. If option <code class="code">-help</code> or <code class="code">--help</code> is
given, <code class="code"><span class="constructor">Arg</span>.parse_argv</code> raises <code class="code"><span class="constructor">Arg</span>.<span class="constructor">Help</span></code> with the help message
as argument.<br>
</div>
<pre><span class="keyword">exception</span> <a name="EXCEPTIONHelp"></a>Help <span class="keyword">of</span> <code class="type">string</code></pre>
<div class="info">
Raised by <code class="code"><span class="constructor">Arg</span>.parse_argv</code> when the user asks for help.<br>
</div>
<pre><span class="keyword">exception</span> <a name="EXCEPTIONBad"></a>Bad <span class="keyword">of</span> <code class="type">string</code></pre>
<div class="info">
Functions in <code class="code">spec</code> or <code class="code">anon_fun</code> can raise <code class="code"><span class="constructor">Arg</span>.<span class="constructor">Bad</span></code> with an error
message to reject invalid arguments.
<code class="code"><span class="constructor">Arg</span>.<span class="constructor">Bad</span></code> is also raised by <code class="code"><span class="constructor">Arg</span>.parse_argv</code> in case of an error.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALusage"></a>usage : <code class="type">(<a href="Arg.html#TYPEkey">key</a> * <a href="Arg.html#TYPEspec">spec</a> * <a href="Arg.html#TYPEdoc">doc</a>) list -> <a href="Arg.html#TYPEusage_msg">usage_msg</a> -> unit</code></pre><div class="info">
<code class="code"><span class="constructor">Arg</span>.usage speclist usage_msg</code> prints an error message including
the list of valid options. This is the same message that
<a href="Arg.html#VALparse"><code class="code"><span class="constructor">Arg</span>.parse</code></a> prints in case of error.
<code class="code">speclist</code> and <code class="code">usage_msg</code> are the same as for <code class="code"><span class="constructor">Arg</span>.parse</code>.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALalign"></a>align : <code class="type">(<a href="Arg.html#TYPEkey">key</a> * <a href="Arg.html#TYPEspec">spec</a> * <a href="Arg.html#TYPEdoc">doc</a>) list -> (<a href="Arg.html#TYPEkey">key</a> * <a href="Arg.html#TYPEspec">spec</a> * <a href="Arg.html#TYPEdoc">doc</a>) list</code></pre><div class="info">
Align the documentation strings by inserting spaces at the first
space, according to the length of the keyword. Use a
space as the first character in a doc string if you want to
align the whole string. The doc strings corresponding to
<code class="code"><span class="constructor">Symbol</span></code> arguments are not aligned.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALcurrent"></a>current : <code class="type">int <a href="Pervasives.html#TYPEref">ref</a></code></pre><div class="info">
Position (in <a href="Sys.html#VALargv"><code class="code"><span class="constructor">Sys</span>.argv</code></a>) of the argument being processed. You can
change this value, e.g. to force <a href="Arg.html#VALparse"><code class="code"><span class="constructor">Arg</span>.parse</code></a> to skip some arguments.
<a href="Arg.html#VALparse"><code class="code"><span class="constructor">Arg</span>.parse</code></a> uses the initial value of <a href="Arg.html#VALcurrent"><code class="code"><span class="constructor">Arg</span>.current</code></a> as the index of
argument 0 (the program name) and starts parsing arguments
at the next element.<br>
</div>
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