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73 lines
2.7 KiB
73 lines
2.7 KiB
4 months ago
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:mod:`user` --- User-specific configuration hook
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================================================
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.. module:: user
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:synopsis: A standard way to reference user-specific modules.
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:deprecated:
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.. deprecated:: 2.6
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The :mod:`user` module has been removed in Python 3.
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.. index::
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pair: .pythonrc.py; file
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triple: user; configuration; file
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As a policy, Python doesn't run user-specified code on startup of Python
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programs. (Only interactive sessions execute the script specified in the
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:envvar:`PYTHONSTARTUP` environment variable if it exists).
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However, some programs or sites may find it convenient to allow users to have a
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standard customization file, which gets run when a program requests it. This
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module implements such a mechanism. A program that wishes to use the mechanism
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must execute the statement ::
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import user
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.. index:: builtin: execfile
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The :mod:`user` module looks for a file :file:`.pythonrc.py` in the user's home
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directory and if it can be opened, executes it (using :func:`execfile`) in its
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own (the module :mod:`user`'s) global namespace. Errors during this phase are
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not caught; that's up to the program that imports the :mod:`user` module, if it
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wishes. The home directory is assumed to be named by the :envvar:`HOME`
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environment variable; if this is not set, the current directory is used.
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The user's :file:`.pythonrc.py` could conceivably test for ``sys.version`` if it
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wishes to do different things depending on the Python version.
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A warning to users: be very conservative in what you place in your
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:file:`.pythonrc.py` file. Since you don't know which programs will use it,
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changing the behavior of standard modules or functions is generally not a good
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idea.
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A suggestion for programmers who wish to use this mechanism: a simple way to let
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users specify options for your package is to have them define variables in their
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:file:`.pythonrc.py` file that you test in your module. For example, a module
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:mod:`spam` that has a verbosity level can look for a variable
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``user.spam_verbose``, as follows::
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import user
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verbose = bool(getattr(user, "spam_verbose", 0))
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(The three-argument form of :func:`getattr` is used in case the user has not
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defined ``spam_verbose`` in their :file:`.pythonrc.py` file.)
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Programs with extensive customization needs are better off reading a
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program-specific customization file.
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Programs with security or privacy concerns should *not* import this module; a
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user can easily break into a program by placing arbitrary code in the
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:file:`.pythonrc.py` file.
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Modules for general use should *not* import this module; it may interfere with
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the operation of the importing program.
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.. seealso::
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Module :mod:`site`
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Site-wide customization mechanism.
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