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<H3><A NAME="SECTION0082136000000000000000"></A><A NAME="optparse-standard-option-types"></A>
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6.21.3.6 Standard option types
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<P>
<tt class="module">optparse</tt> has six built-in option types: <code>string</code>, <code>int</code>, <code>long</code>,
<code>choice</code>, <code>float</code> and <code>complex</code>.  If you need to add new option
types, see section&nbsp;<A HREF="#optparse-extending"><tex2html_cross_ref_visible_mark></A>, Extending <tt class="module">optparse</tt>.

<P>
Arguments to string options are not checked or converted in any way: the
text on the command line is stored in the destination (or passed to the
callback) as-is.

<P>
Integer arguments are passed to <code>int()</code> to convert them to Python
integers.  If <code>int()</code> fails, so will <tt class="module">optparse</tt>, although with a more
useful error message.  (Internally, <tt class="module">optparse</tt> raises OptionValueError;
OptionParser catches this exception higher up and terminates your
program with a useful error message.)

<P>
Likewise, <code>float</code> arguments are passed to <code>float()</code> for conversion,
<code>long</code> arguments to <code>long()</code>, and <code>complex</code> arguments to
<code>complex()</code>.  Apart from that, they are handled identically to integer
arguments.

<P>
<code>choice</code> options are a subtype of <code>string</code> options.  The <code>choices</code>
option attribute (a sequence of strings) defines the set of allowed
option arguments.  <code>optparse.check_choice()</code> compares
user-supplied option arguments against this master list and raises
OptionValueError if an invalid string is given.

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