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<H3><A NAME="SECTION0082137000000000000000"></A><A NAME="optparse-parsing-arguments"></A>
<BR>
6.21.3.7 Parsing arguments
</H3>

<P>
The whole point of creating and populating an OptionParser is to call
its <tt class="method">parse_args()</tt> method:
<div class="verbatim"><pre>
(options, args) = parser.parse_args(args=None, options=None)
</pre></div>

<P>
where the input parameters are
<DL>
<DT><STRONG><code>args</code></STRONG></DT>
<DD>the list of arguments to process (<code>sys.argv[1:]</code> by default)
</DD>
<DT><STRONG><code>options</code></STRONG></DT>
<DD>object to store option arguments in (a new instance of
optparse.Values by default)
</DD>
</DL>

<P>
and the return values are
<DL>
<DT><STRONG><code>options</code></STRONG></DT>
<DD>the same object as was passed in as <code>options</code>, or the new
optparse.Values instance created by <tt class="module">optparse</tt>
</DD>
<DT><STRONG><code>args</code></STRONG></DT>
<DD>the leftover positional arguments after all options have been
processed
</DD>
</DL>

<P>
The most common usage is to supply neither keyword argument.  If you
supply a <code>values</code> object, it will be repeatedly modified with a
<code>setattr()</code> call for every option argument written to an option
destination, and finally returned by <tt class="method">parse_args()</tt>.

<P>
If <tt class="method">parse_args()</tt> encounters any errors in the argument list, it calls
the OptionParser's <tt class="method">error()</tt> method with an appropriate end-user error
message.  This ultimately terminates your process with an exit status of
2 (the traditional <span class="Unix">Unix</span> exit status for command-line errors).

<P>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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