2 :mod:`user` --- User-specific configuration hook
3 ================================================
6 :synopsis: A standard way to reference user-specific modules.
10 The :mod:`user` module has been removed in Python 3.0.
13 pair: .pythonrc.py; file
14 triple: user; configuration; file
16 As a policy, Python doesn't run user-specified code on startup of Python
17 programs. (Only interactive sessions execute the script specified in the
18 :envvar:`PYTHONSTARTUP` environment variable if it exists).
20 However, some programs or sites may find it convenient to allow users to have a
21 standard customization file, which gets run when a program requests it. This
22 module implements such a mechanism. A program that wishes to use the mechanism
23 must execute the statement ::
27 .. index:: builtin: execfile
29 The :mod:`user` module looks for a file :file:`.pythonrc.py` in the user's home
30 directory and if it can be opened, executes it (using :func:`execfile`) in its
31 own (the module :mod:`user`'s) global namespace. Errors during this phase are
32 not caught; that's up to the program that imports the :mod:`user` module, if it
33 wishes. The home directory is assumed to be named by the :envvar:`HOME`
34 environment variable; if this is not set, the current directory is used.
36 The user's :file:`.pythonrc.py` could conceivably test for ``sys.version`` if it
37 wishes to do different things depending on the Python version.
39 A warning to users: be very conservative in what you place in your
40 :file:`.pythonrc.py` file. Since you don't know which programs will use it,
41 changing the behavior of standard modules or functions is generally not a good
44 A suggestion for programmers who wish to use this mechanism: a simple way to let
45 users specify options for your package is to have them define variables in their
46 :file:`.pythonrc.py` file that you test in your module. For example, a module
47 :mod:`spam` that has a verbosity level can look for a variable
48 ``user.spam_verbose``, as follows::
52 verbose = bool(getattr(user, "spam_verbose", 0))
54 (The three-argument form of :func:`getattr` is used in case the user has not
55 defined ``spam_verbose`` in their :file:`.pythonrc.py` file.)
57 Programs with extensive customization needs are better off reading a
58 program-specific customization file.
60 Programs with security or privacy concerns should *not* import this module; a
61 user can easily break into a program by placing arbitrary code in the
62 :file:`.pythonrc.py` file.
64 Modules for general use should *not* import this module; it may interfere with
65 the operation of the importing program.
71 Site-wide customization mechanism.