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<title>3.31 user -- User-specific configuration hook
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<H1><A NAME=
"SECTION0053100000000000000000">
3.31 <tt class=
"module">user
</tt> --
User-specific configuration hook
</A>
<A NAME=
"module-user"></A>
<a id='l2h-
808' xml:id='l2h-
808'
></a><a id='l2h-
809' xml:id='l2h-
809'
></a>
As a policy, Python doesn't run user-specified code on startup of
Python programs. (Only interactive sessions execute the script
specified in the
<a class=
"envvar" id='l2h-
811' xml:id='l2h-
811'
>PYTHONSTARTUP
</a> environment variable if it
However, some programs or sites may find it convenient to allow users
to have a standard customization file, which gets run when a program
requests it. This module implements such a mechanism. A program
that wishes to use the mechanism must execute the statement
<div class=
"verbatim"><pre>
The
<tt class=
"module">user
</tt> module looks for a file
<span class=
"file">.pythonrc.py
</span> in the user's
home directory and if it can be opened, executes it (using
<tt class=
"function">execfile()
</tt><a id='l2h-
810' xml:id='l2h-
810'
></a>) in its own (the
module
<tt class=
"module">user
</tt>'s) global namespace. Errors during this phase
are not caught; that's up to the program that imports the
<tt class=
"module">user
</tt> module, if it wishes. The home directory is assumed to
be named by the
<a class=
"envvar" id='l2h-
812' xml:id='l2h-
812'
>HOME
</a> environment variable; if this is not set,
the current directory is used.
The user's
<span class=
"file">.pythonrc.py
</span> could conceivably test for
<code>sys.version
</code> if it wishes to do different things depending on
A warning to users: be very conservative in what you place in your
<span class=
"file">.pythonrc.py
</span> file. Since you don't know which programs will
use it, changing the behavior of standard modules or functions is
generally not a good idea.
A suggestion for programmers who wish to use this mechanism: a simple
way to let users specify options for your package is to have them
define variables in their
<span class=
"file">.pythonrc.py
</span> file that you test in
your module. For example, a module
<tt class=
"module">spam
</tt> that has a verbosity
level can look for a variable
<code>user.spam_verbose
</code>, as follows:
<div class=
"verbatim"><pre>
verbose = bool(getattr(user,
"spam_verbose",
0))
(The three-argument form of
<tt class=
"function">getattr()
</tt> is used in case
the user has not defined
<code>spam_verbose
</code> in their
<span class=
"file">.pythonrc.py
</span> file.)
Programs with extensive customization needs are better off reading a
program-specific customization file.
Programs with security or privacy concerns should
<em>not
</em> import
this module; a user can easily break into a program by placing
arbitrary code in the
<span class=
"file">.pythonrc.py
</span> file.
Modules for general use should
<em>not
</em> import this module; it may
interfere with the operation of the importing program.
<p class=
"heading">See Also:
</p>
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-site.html">site
</a></tt>:
</b>
<dd>Site-wide customization mechanism.
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<span class=
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2.4.2, documentation updated on
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2005.
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