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<h3>Modules</h3>
<p>As your programs grow in size, you抣l probably want to break them into multiple files for easier maintenance. To do this, Python allows you to put definitions in a file and use them as a <i>module</I> that can be imported into other programs and scripts. To create a module, put the relevant statements and definitions into a file that has the same name as the module. (Note: The file must have a .py suffix.) For example:</P>
<PRe>
# file : div.py
def divide(a,b):
q = a/b # If a and b are integers, q is an integer
r = a - q*b
return (q,r) </pre>
<P>To use your module in other programs, you can use the <TT Class="monofont">import</TT> statement:</P>
<Pre>
import div
a, b = div.divide(2305, 29) </pre>
<p><tt class="monofont">import</tt> creates a new namespace that contains all the objects defined in the module. To access this namespace, simply use the name of the module as a prefix, as in <tt claSs="monofont">div.divide()</tT> in the preceding example.</p>
<p>If you want to import a module using a different name, supply the <tT clasS="monofont">import</tt> statement with an optional <tT CLAss="monofont">as</tt> qualifier as follows:</P>
<PRE>
import div as foo
a,b = foo.divide(2305,29) </pre>
<p>To import specific definitions into the current namespace, use the <TT CLass="monofont">from</tT> statement:</P>
<PRe>
from div import divide
a,b = divide(2305,29) # No longer need the div prefix </pre>
<p>To load all of a module抯 contents into the current namespace, you can also use the following:</p>
<pre>
from div import * </pre>
<p>Finally, the <tt class="monofont">dir()</Tt> function lists the contents of a module and is a useful tool for interactive experimentation, since it can be used to provide a list of available functions and variables:</p>
<Pre>
>>> import string
>>> dir(string)
['_ _builtins_ _', '_ _doc_ _', '_ _file_ _', '_ _name_ _', '_idmap',
'_idmapL', '_lower', '_swapcase', '_upper', 'atof', 'atof_error',
'atoi', 'atoi_error', 'atol', 'atol_error', 'capitalize',
'capwords', 'center', 'count', 'digits', 'expandtabs', 'find',
...
>>> </pRe>
</fonT>
<P><TABLE width="100%" border=0><TR valign="top"><TD><font size=1 color="#C0C0C0"><br></font></TD><TD align=right><font size=1 color="#C0C0C0">Last updated on 3/28/2002<br>Python Essential Reference, Second Edition, © 2002 New Riders Publishing</font></TD></TR></TABLE></P>
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