1 

     2 :mod:`user` --- User-specific configuration hook

     3 ================================================

     4 

     5 .. module:: user

     6    :synopsis: A standard way to reference user-specific modules.

     7    :deprecated:

     8 

     9 .. deprecated:: 2.6

    10    The :mod:`user` module has been removed in Python 3.0.

    11 

    12 .. index::

    13    pair: .pythonrc.py; file

    14    triple: user; configuration; file

    15 

    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).

    19 

    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 ::

    24 

    25    import user

    26 

    27 .. index:: builtin: execfile

    28 

    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.

    35 

    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.

    38 

    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

    42 idea.

    43 

    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::

    49 

    50    import user

    51 

    52    verbose = bool(getattr(user, "spam_verbose", 0))

    53 

    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.)

    56 

    57 Programs with extensive customization needs are better off reading a

    58 program-specific customization file.

    59 

    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.

    63 

    64 Modules for general use should *not* import this module; it may interfere with

    65 the operation of the importing program.

    66 

    67 

    68 .. seealso::

    69 

    70    Module :mod:`site`

    71       Site-wide customization mechanism.

    72