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<H3><A NAME="SECTION004291000000000000000"> </A>
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2.2.9.1 Modules
</H3>
<P>
The only special operation on a module is attribute access:
<code><var>m</var>.<var>name</var></code>, where <var>m</var> is a module and <var>name</var>
accesses a name defined in <var>m</var>'s symbol table. Module attributes
can be assigned to. (Note that the <tt class="keyword">import</tt> statement is not,
strictly speaking, an operation on a module object; <code>import
<var>foo</var></code> does not require a module object named <var>foo</var> to exist,
rather it requires an (external) <i>definition</i> for a module named
<var>foo</var> somewhere.)
<P>
A special member of every module is <tt class="member">__dict__</tt>.
This is the dictionary containing the module's symbol table.
Modifying this dictionary will actually change the module's symbol
table, but direct assignment to the <tt class="member">__dict__</tt> attribute is not
possible (you can write <code><var>m</var>.__dict__['a'] = 1</code>, which
defines <code><var>m</var>.a</code> to be <code>1</code>, but you can't write
<code><var>m</var>.__dict__ = {}</code>.
<P>
Modules built into the interpreter are written like this:
<code><module 'sys' (built-in)></code>. If loaded from a file, they are
written as <code><module 'os' from
'/usr/local/lib/python2.2/os.pyc'></code>.
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<span class="release-info">Release 2.2, documentation updated on December 21, 2001.</span>
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