mirror of
https://github.com/python/cpython.git
synced 2025-10-31 18:28:49 +00:00
71 lines
2.6 KiB
TeX
71 lines
2.6 KiB
TeX
\section{\module{user} ---
|
|
User-specific configuration hook}
|
|
|
|
\declaremodule{standard}{user}
|
|
\modulesynopsis{A standard way to reference user-specific modules.}
|
|
|
|
|
|
\indexii{.pythonrc.py}{file}
|
|
\indexiii{user}{configuration}{file}
|
|
|
|
As a policy, Python doesn't run user-specified code on startup of
|
|
Python programs. (Only interactive sessions execute the script
|
|
specified in the \envvar{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
|
|
|
|
\begin{verbatim}
|
|
import user
|
|
\end{verbatim}
|
|
|
|
The \module{user} module looks for a file \file{.pythonrc.py} in the user's
|
|
home directory and if it can be opened, executes it (using
|
|
\function{execfile()}\bifuncindex{execfile}) in its own (the
|
|
module \module{user}'s) global namespace. Errors during this phase
|
|
are not caught; that's up to the program that imports the
|
|
\module{user} module, if it wishes. The home directory is assumed to
|
|
be named by the \envvar{HOME} environment variable; if this is not set,
|
|
the current directory is used.
|
|
|
|
The user's \file{.pythonrc.py} could conceivably test for
|
|
\code{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
|
|
\file{.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 \file{.pythonrc.py} file that you test in
|
|
your module. For example, a module \module{spam} that has a verbosity
|
|
level can look for a variable \code{user.spam_verbose}, as follows:
|
|
|
|
\begin{verbatim}
|
|
import user
|
|
|
|
verbose = bool(getattr(user, "spam_verbose", 0))
|
|
\end{verbatim}
|
|
|
|
(The three-argument form of \function{getattr()} is used in case
|
|
the user has not defined \code{spam_verbose} in their
|
|
\file{.pythonrc.py} file.)
|
|
|
|
Programs with extensive customization needs are better off reading a
|
|
program-specific customization file.
|
|
|
|
Programs with security or privacy concerns should \emph{not} import
|
|
this module; a user can easily break into a program by placing
|
|
arbitrary code in the \file{.pythonrc.py} file.
|
|
|
|
Modules for general use should \emph{not} import this module; it may
|
|
interfere with the operation of the importing program.
|
|
|
|
\begin{seealso}
|
|
\seemodule{site}{Site-wide customization mechanism.}
|
|
\end{seealso}
|