mirror of
https://github.com/python/cpython.git
synced 2024-12-12 03:04:15 +08:00
138 lines
6.4 KiB
ReStructuredText
138 lines
6.4 KiB
ReStructuredText
:mod:`runpy` --- Locating and executing Python modules
|
|
======================================================
|
|
|
|
.. module:: runpy
|
|
:synopsis: Locate and run Python modules without importing them first.
|
|
.. moduleauthor:: Nick Coghlan <ncoghlan@gmail.com>
|
|
|
|
|
|
The :mod:`runpy` module is used to locate and run Python modules without
|
|
importing them first. Its main use is to implement the :option:`-m` command
|
|
line switch that allows scripts to be located using the Python module
|
|
namespace rather than the filesystem.
|
|
|
|
The :mod:`runpy` module provides two functions:
|
|
|
|
|
|
.. function:: run_module(mod_name, init_globals=None, run_name=None, alter_sys=False)
|
|
|
|
Execute the code of the specified module and return the resulting module
|
|
globals dictionary. The module's code is first located using the standard
|
|
import mechanism (refer to :pep:`302` for details) and then executed in a
|
|
fresh module namespace.
|
|
|
|
If the supplied module name refers to a package rather than a normal
|
|
module, then that package is imported and the ``__main__`` submodule within
|
|
that package is then executed and the resulting module globals dictionary
|
|
returned.
|
|
|
|
The optional dictionary argument *init_globals* may be used to pre-populate
|
|
the module's globals dictionary before the code is executed. The supplied
|
|
dictionary will not be modified. If any of the special global variables
|
|
below are defined in the supplied dictionary, those definitions are
|
|
overridden by :func:`run_module`.
|
|
|
|
The special global variables ``__name__``, ``__file__``, ``__cached__``,
|
|
``__loader__``
|
|
and ``__package__`` are set in the globals dictionary before the module
|
|
code is executed (Note that this is a minimal set of variables - other
|
|
variables may be set implicitly as an interpreter implementation detail).
|
|
|
|
``__name__`` is set to *run_name* if this optional argument is not
|
|
:const:`None`, to ``mod_name + '.__main__'`` if the named module is a
|
|
package and to the *mod_name* argument otherwise.
|
|
|
|
``__file__`` is set to the name provided by the module loader. If the
|
|
loader does not make filename information available, this variable is set
|
|
to :const:`None`.
|
|
|
|
``__cached__`` will be set to ``None``.
|
|
|
|
``__loader__`` is set to the :pep:`302` module loader used to retrieve the
|
|
code for the module (This loader may be a wrapper around the standard
|
|
import mechanism).
|
|
|
|
``__package__`` is set to *mod_name* if the named module is a package and
|
|
to ``mod_name.rpartition('.')[0]`` otherwise.
|
|
|
|
If the argument *alter_sys* is supplied and evaluates to :const:`True`,
|
|
then ``sys.argv[0]`` is updated with the value of ``__file__`` and
|
|
``sys.modules[__name__]`` is updated with a temporary module object for the
|
|
module being executed. Both ``sys.argv[0]`` and ``sys.modules[__name__]``
|
|
are restored to their original values before the function returns.
|
|
|
|
Note that this manipulation of :mod:`sys` is not thread-safe. Other threads
|
|
may see the partially initialised module, as well as the altered list of
|
|
arguments. It is recommended that the :mod:`sys` module be left alone when
|
|
invoking this function from threaded code.
|
|
|
|
|
|
.. versionchanged:: 3.1
|
|
Added ability to execute packages by looking for a ``__main__`` submodule.
|
|
|
|
|
|
.. function:: run_path(file_path, init_globals=None, run_name=None)
|
|
|
|
Execute the code at the named filesystem location and return the resulting
|
|
module globals dictionary. As with a script name supplied to the CPython
|
|
command line, the supplied path may refer to a Python source file, a
|
|
compiled bytecode file or a valid sys.path entry containing a ``__main__``
|
|
module (e.g. a zipfile containing a top-level ``__main__.py`` file).
|
|
|
|
For a simple script, the specified code is simply executed in a fresh
|
|
module namespace. For a valid sys.path entry (typically a zipfile or
|
|
directory), the entry is first added to the beginning of ``sys.path``. The
|
|
function then looks for and executes a :mod:`__main__` module using the
|
|
updated path. Note that there is no special protection against invoking
|
|
an existing :mod:`__main__` entry located elsewhere on ``sys.path`` if
|
|
there is no such module at the specified location.
|
|
|
|
The optional dictionary argument *init_globals* may be used to pre-populate
|
|
the module's globals dictionary before the code is executed. The supplied
|
|
dictionary will not be modified. If any of the special global variables
|
|
below are defined in the supplied dictionary, those definitions are
|
|
overridden by :func:`run_path`.
|
|
|
|
The special global variables ``__name__``, ``__file__``, ``__loader__``
|
|
and ``__package__`` are set in the globals dictionary before the module
|
|
code is executed (Note that this is a minimal set of variables - other
|
|
variables may be set implicitly as an interpreter implementation detail).
|
|
|
|
``__name__`` is set to *run_name* if this optional argument is not
|
|
:const:`None` and to ``'<run_path>'`` otherwise.
|
|
|
|
``__file__`` is set to the name provided by the module loader. If the
|
|
loader does not make filename information available, this variable is set
|
|
to :const:`None`. For a simple script, this will be set to ``file_path``.
|
|
|
|
``__loader__`` is set to the :pep:`302` module loader used to retrieve the
|
|
code for the module (This loader may be a wrapper around the standard
|
|
import mechanism). For a simple script, this will be set to :const:`None`.
|
|
|
|
``__package__`` is set to ``__name__.rpartition('.')[0]``.
|
|
|
|
A number of alterations are also made to the :mod:`sys` module. Firstly,
|
|
``sys.path`` may be altered as described above. ``sys.argv[0]`` is updated
|
|
with the value of ``file_path`` and ``sys.modules[__name__]`` is updated
|
|
with a temporary module object for the module being executed. All
|
|
modifications to items in :mod:`sys` are reverted before the function
|
|
returns.
|
|
|
|
Note that, unlike :func:`run_module`, the alterations made to :mod:`sys`
|
|
are not optional in this function as these adjustments are essential to
|
|
allowing the execution of sys.path entries. As the thread safety
|
|
limitations still apply, use of this function in threaded code should be
|
|
either serialised with the import lock or delegated to a separate process.
|
|
|
|
.. versionadded:: 3.2
|
|
|
|
.. seealso::
|
|
|
|
:pep:`338` - Executing modules as scripts
|
|
PEP written and implemented by Nick Coghlan.
|
|
|
|
:pep:`366` - Main module explicit relative imports
|
|
PEP written and implemented by Nick Coghlan.
|
|
|
|
:ref:`using-on-general` - CPython command line details
|