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<H3><A NAME="SECTION00821310000000000000000"></A><A NAME="optparse-other-methods"></A>
<BR>
6.21.3.10 Other methods
</H3>

<P>
OptionParser supports several other public methods:

<UL>
<LI>
<code>set_usage(usage)</code>

<P>
Set the usage string according to the rules described above for the
<code>usage</code> constructor keyword argument.  Passing <code>None</code> sets the
default usage string; use <code>SUPPRESS_USAGE</code> to suppress a usage
message.

<P>
</LI>
<LI>
<code>enable_interspersed_args()</code>, <code>disable_interspersed_args()</code>

<P>
Enable/disable positional arguments interspersed with options, similar
to GNU getopt (enabled by default).  For example, if <code>"-a"</code> and
<code>"-b"</code> are both simple options that take no arguments, <tt class="module">optparse</tt>
normally accepts this syntax:
<div class="verbatim"><pre>
prog -a arg1 -b arg2
</pre></div>

<P>
and treats it as equivalent to
<div class="verbatim"><pre>
prog -a -b arg1 arg2
</pre></div>

<P>
To disable this feature, call <code>disable_interspersed_args()</code>.  This
restores traditional <span class="Unix">Unix</span> syntax, where option parsing stops with the
first non-option argument.

<P>
</LI>
<LI>
<code>set_defaults(dest=value, ...)</code>

<P>
Set default values for several option destinations at once.  Using
<tt class="method">set_defaults()</tt> is the preferred way to set default values for
options, since multiple options can share the same destination.  For
example, if several ``mode'' options all set the same destination, any
one of them can set the default, and the last one wins:
<div class="verbatim"><pre>
parser.add_option("--advanced", action="store_const",
                  dest="mode", const="advanced",
                  default="novice")    # overridden below
parser.add_option("--novice", action="store_const",
                  dest="mode", const="novice",
                  default="advanced")  # overrides above setting
</pre></div>

<P>
To avoid this confusion, use <tt class="method">set_defaults()</tt>:
<div class="verbatim"><pre>
parser.set_defaults(mode="advanced")
parser.add_option("--advanced", action="store_const",
                  dest="mode", const="advanced")
parser.add_option("--novice", action="store_const",
                  dest="mode", const="novice")
</pre></div>

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