3.22 Standard Module user

   

As a policy, Python doesn't run user-specified code on startup of Python programs. (Only interactive sessions execute the script specified in the $PYTHONSTARTUP environment variable if it exists).

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

import user

The user module looks for a file ".pythonrc.py" in the user's home directory and if it can be opened, exececutes it (using execfile() ) in its own (i.e. the module user's) global namespace. Errors during this phase are not caught; that's up to the program that imports the user module, if it wishes. The home directory is assumed to be named by the $HOME environment variable; if this is not set, the current directory is used.

The user's ".pythonrc.py" could conceivably test for sys.version if it wishes to do different things depending on the Python version.

A warning to users: be very conservative in what you place in your ".pythonrc.py" 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 ".pythonrc.py" file that you test in your module. For example, a module spam that has a verbosity level can look for a variable user.spam_verbose, as follows:

import user
try:
    verbose = user.spam_verbose  # user's verbosity preference
except AttributeError:
    verbose = 0                  # default verbosity

Programs with extensive customization needs are better off reading a program-specific customization file.

Programs with security or privacy concerns should not import this module; a user can easily break into a a program by placing arbitrary code in the ".pythonrc.py" file.

Modules for general use should not import this module; it may interfere with the operation of the importing program.

See Also:

Module site   (site-wide customization mechanism)