219 lines
7.3 KiB
ReStructuredText
219 lines
7.3 KiB
ReStructuredText
:mod:`sysconfig` --- Provide access to Python's configuration information
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=========================================================================
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.. module:: sysconfig
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:synopsis: Python's configuration information
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.. moduleauthor:: Tarek Ziade <tarek@ziade.org>
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.. sectionauthor:: Tarek Ziade <tarek@ziade.org>
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.. versionadded:: 2.7
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.. index::
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single: configuration information
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The :mod:`sysconfig` module provides access to Python's configuration
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information like the list of installation paths and the configuration
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variables relevant for the current platform.
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Configuration variables
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-----------------------
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A Python distribution contains a :file:`Makefile` file and a :file:`python.h`
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that are used to build the Python binary itself, but also any C extension
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created in a third party project and compiled using :mod:`distutils`.
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:mod:`sysconfig` put all variables found in these files in a dictionnary
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that can be accessed using :func:`get_config_vars` or :func:`get_config_var`.
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Notice that on Windows, it's a much smaller set.
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.. function:: get_config_vars(\*args)
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With no arguments, return a dictionary of all configuration
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variables relevant for the current platform.
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With arguments, return a list of values that result from looking up
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each argument in the configuration variable dictionary.
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For each argument, if the value is not found, returns None.
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.. function:: get_config_var(name)
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Return the value of a single variable *name*. Equivalent to
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get_config_vars().get(name).
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If *name* is not found, return None.
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Example of usage::
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>>> import sysconfig
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>>> sysconfig.get_config_var('Py_ENABLE_SHARED')
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0
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>>> sysconfig.get_config_var('LIBDIR')
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'/usr/local/lib'
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>>> sysconfig.get_config_vars('AR', 'CXX')
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['ar', 'g++']
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Installation paths
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------------------
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Python uses an installation scheme that differs depending on the platform
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and on the installation options. These schemes are stored in :mod:`sysconfig`
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under unique identifiers based on the value returned by :const:`os.name`.
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Every new component that is installed using :mod:`distutils` or a
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Distutils-based system will follow the same scheme to copy its file in the
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right places.
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Python currently supports seven schemes:
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- *posix_prefix*: scheme for posix platforms like Linux or Mac OS X. This is the
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default scheme used when Python or a component is installed.
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- *posix_home*: scheme for posix platform used when a *home* option is used
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upon installation. This scheme is used when a component is installed through
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Distutils with a specific home prefix.
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- *posix_user*: scheme for posix platform used when a component is installed
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through Distutils and the *user* option is used. This scheme defines paths
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located under the user home directory.
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- *nt*: scheme for nt platforms like Windows.
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- *nt_user*: scheme for nt platforms, when the *user* option is used.
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- *os2*: scheme for OS2 platforms.
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- *os2_home*: scheme for OS2 patforms, when the *user* option is used.
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Each scheme is itself composed of a series of paths and each path has a unique
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identifier. Python currently uses eight paths:
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- *stdlib*: directory containing the standard Python library files that are
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not platform-specific.
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- *platstdlib*: directory containing the standard Python library files that
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are platform-specific files.
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- *platlib*: directory for the site-specific, platform-specific files.
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- *purelib*: directory for the site-specific, non platform-specific files.
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- *include*: directory containing the non-platform-specific header files.
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- *platinclude*: directory containing the platform-specific header files.
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- *scripts*: directory containing the script files.
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- *data*: directory containing the data files.
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:mod:`sysconfig` provides some functions to read these paths.
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.. function:: get_scheme_names()
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Return a tuple containing all schemes currently supported in
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:mod:`sysconfig`.
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.. function:: get_path_names()
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Return a tuple containing all path names currently supported in
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:mod:`sysconfig`.
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.. function:: get_path(name, [scheme, [vars, [expand]]])
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Return an installation path corresponding to the path *name*, from the
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install scheme named *scheme*.
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*name* has to be a value from the list returned by :func:`get_path_names`.
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:mod:`sysconfig` stores installation paths corresponding to the each
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path name, for each platform, with variables to be expanded. For instance
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the `stdlib` path for the `nt` scheme is: `{base}/Lib`.
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:func:`get_path` will use the variables returned by :func:`get_config_vars`
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to expand the path. All variables have default values for each platform
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so one may call this function and get the default value.
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If *scheme* is provided, it must be a value from the list returned by
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:func:`get_path_names`. Otherwise, the default scheme for the current
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platform is used.
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If *vars* is provided, it must be a dictionnary of variables that will
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update the dictionnary return by :func:`get_config_vars`.
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If *expand* is set to False, the path will not be expanded using
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the variables.
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If *name* is not found, return None.
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.. function:: get_paths([scheme, [vars, [expand]]])
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Return a dictionnary containing all installation paths corresponding to an
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installation scheme. See :func:`get_path` for more information.
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If *scheme* is not provided, will use the default scheme for the current
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platform.
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If *vars* is provided, it must be a dictionnary of variables that will
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update the dictionnary used to expand the paths.
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If *expand* is set to False, the paths will not be expanded.
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If *scheme* is not an existing scheme, :func:`get_paths` will raise a
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:exc:`KeyError`.
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Other functions
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---------------
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.. function:: get_python_version()
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Return the MAJOR.MINOR Python version number as a string. Similar to
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``sys.version[:3]``.
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.. function:: get_platform()
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Return a string that identifies the current platform.
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This is used mainly to distinguish platform-specific build directories and
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platform-specific built distributions. Typically includes the OS name
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and version and the architecture (as supplied by 'os.uname()'),
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although the exact information included depends on the OS; eg. for IRIX
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the architecture isn't particularly important (IRIX only runs on SGI
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hardware), but for Linux the kernel version isn't particularly
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important.
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Examples of returned values:
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- linux-i586
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- linux-alpha (?)
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- solaris-2.6-sun4u
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- irix-5.3
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- irix64-6.2
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Windows will return one of:
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- win-amd64 (64bit Windows on AMD64 (aka x86_64, Intel64, EM64T, etc)
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- win-ia64 (64bit Windows on Itanium)
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- win32 (all others - specifically, sys.platform is returned)
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Mac OS X can return :
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- macosx-10.6-ppc
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- macosx-10.4-ppc64
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- macosx-10.3-i386
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- macosx-10.4-fat
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For other non-POSIX platforms, currently just returns 'sys.platform'.
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.. function:: is_python_build():
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Returns True if the current Python installation was built from source.
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.. function:: parse_config_h(fp[, vars]):
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Parse a config.h-style file.
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*fp* is a file-like object pointing to the config.h-like file.
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A dictionary containing name/value pairs is returned. If an optional
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dictionary is passed in as the second argument, it is used instead of a
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new dictionary, and updated with the values read in the file.
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.. function:: get_config_h_filename():
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Returns the path of pyconfig.h
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