cpython/Doc/library/runpy.rst

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: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>
2011-01-26 21:20:32 -04:00
**Source code:** :source:`Lib/runpy.py`
--------------
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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.
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Note that this is *not* a sandbox module - all code is executed in the
current process, and any side effects (such as cached imports of other
modules) will remain in place after the functions have returned.
Furthermore, any functions and classes defined by the executed code are not
guaranteed to work correctly after a :mod:`runpy` function has returned.
If that limitation is not acceptable for a given use case, :mod:`importlib`
is likely to be a more suitable choice than this module.
The :mod:`runpy` module provides two functions:
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.. function:: run_module(mod_name, init_globals=None, run_name=None, alter_sys=False)
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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.
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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`.
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The special global variables ``__name__``, ``__spec__``, ``__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).
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``__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.
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``__spec__`` will be set appropriately for the *actually* imported
module (that is, ``__spec__.name`` will always be *mod_name* or
``mod_name + '.__main__``, never *run_name*).
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``__file__``, ``__cached__``, ``__loader__`` and ``__package__`` are
:ref:`set as normal <import-mod-attrs>` based on the module spec.
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If the argument *alter_sys* is supplied and evaluates to :const:`True`,
then ``sys.argv[0]`` is updated with the value of ``__file__`` and
Merge the trunk changes in. Breaks socket.ssl for now. Merged revisions 57392-57619 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r57395 | georg.brandl | 2007-08-24 19:23:23 +0200 (Fri, 24 Aug 2007) | 2 lines Bug #1011: fix rfc822.Message.getheader docs. ........ r57397 | georg.brandl | 2007-08-24 19:38:49 +0200 (Fri, 24 Aug 2007) | 2 lines Patch #1006: port test_winreg to unittest. ........ r57398 | georg.brandl | 2007-08-24 19:46:54 +0200 (Fri, 24 Aug 2007) | 2 lines Fix #1012: wrong URL to :mod:`site` in install/index.rst. ........ r57399 | georg.brandl | 2007-08-24 20:07:52 +0200 (Fri, 24 Aug 2007) | 2 lines Patch #1008: port test_signal to unittest. ........ r57400 | georg.brandl | 2007-08-24 20:22:54 +0200 (Fri, 24 Aug 2007) | 2 lines Port test_frozen to unittest. ........ r57401 | georg.brandl | 2007-08-24 20:27:43 +0200 (Fri, 24 Aug 2007) | 2 lines Document new utility functions in test_support. ........ r57402 | georg.brandl | 2007-08-24 20:30:06 +0200 (Fri, 24 Aug 2007) | 2 lines Remove test_rgbimg output file, there is no test_rgbimg.py. ........ r57403 | georg.brandl | 2007-08-24 20:35:27 +0200 (Fri, 24 Aug 2007) | 2 lines Remove output file for test_ossaudiodev, also properly close the dsp object. ........ r57404 | georg.brandl | 2007-08-24 20:46:27 +0200 (Fri, 24 Aug 2007) | 2 lines Convert test_linuxaudiodev to unittest. Fix a wrong finally clause in test_ossaudiodev. ........ r57406 | collin.winter | 2007-08-24 21:13:58 +0200 (Fri, 24 Aug 2007) | 1 line Convert test_pkg to use unittest. ........ r57408 | georg.brandl | 2007-08-24 21:22:34 +0200 (Fri, 24 Aug 2007) | 2 lines Catch the correct errors. ........ r57409 | georg.brandl | 2007-08-24 21:33:53 +0200 (Fri, 24 Aug 2007) | 2 lines Port test_class to unittest. Patch #1671298. ........ r57415 | collin.winter | 2007-08-24 23:09:42 +0200 (Fri, 24 Aug 2007) | 1 line Make test_structmembers pass when run with regrtests's -R flag. ........ r57455 | nick.coghlan | 2007-08-25 06:32:07 +0200 (Sat, 25 Aug 2007) | 1 line Revert misguided attempt at fixing incompatibility between -m and -i switches (better fix coming soon) ........ r57456 | nick.coghlan | 2007-08-25 06:35:54 +0200 (Sat, 25 Aug 2007) | 1 line Revert compile.c changes that shouldn't have been included in previous checkin ........ r57461 | nick.coghlan | 2007-08-25 12:50:41 +0200 (Sat, 25 Aug 2007) | 1 line Fix bug 1764407 - the -i switch now does the right thing when using the -m switch ........ r57464 | guido.van.rossum | 2007-08-25 17:08:43 +0200 (Sat, 25 Aug 2007) | 4 lines Server-side SSL and certificate validation, by Bill Janssen. While cleaning up Bill's C style, I may have cleaned up some code he didn't touch as well (in _ssl.c). ........ r57465 | neal.norwitz | 2007-08-25 18:41:36 +0200 (Sat, 25 Aug 2007) | 3 lines Try to get this to build with Visual Studio by moving all the variable declarations to the beginning of a scope. ........ r57466 | neal.norwitz | 2007-08-25 18:54:38 +0200 (Sat, 25 Aug 2007) | 1 line Fix test so it is skipped properly if there is no SSL support. ........ r57467 | neal.norwitz | 2007-08-25 18:58:09 +0200 (Sat, 25 Aug 2007) | 2 lines Fix a few more variables to try to get this to compile with Visual Studio. ........ r57473 | neal.norwitz | 2007-08-25 19:25:17 +0200 (Sat, 25 Aug 2007) | 1 line Try to get this test to pass for systems that do not have SO_REUSEPORT ........ r57482 | gregory.p.smith | 2007-08-26 02:26:00 +0200 (Sun, 26 Aug 2007) | 7 lines keep setup.py from listing unneeded hash modules (_md5, _sha*) as missing when they were not built because _hashlib with openssl provided their functionality instead. don't build bsddb185 if bsddb was built. ........ r57483 | neal.norwitz | 2007-08-26 03:08:16 +0200 (Sun, 26 Aug 2007) | 1 line Fix typo in docstring (missing c in reacquire) ........ r57484 | neal.norwitz | 2007-08-26 03:42:03 +0200 (Sun, 26 Aug 2007) | 2 lines Spell check (also americanify behaviour, it's almost 3 times as common) ........ r57503 | neal.norwitz | 2007-08-26 08:29:57 +0200 (Sun, 26 Aug 2007) | 4 lines Reap children before the test starts so hopefully SocketServer won't find any old children left around which causes an exception in collect_children() and the test to fail. ........ r57510 | neal.norwitz | 2007-08-26 20:50:39 +0200 (Sun, 26 Aug 2007) | 1 line Fail gracefully if the cert files cannot be created ........ r57513 | guido.van.rossum | 2007-08-26 21:35:09 +0200 (Sun, 26 Aug 2007) | 4 lines Bill Janssen wrote: Here's a patch which makes test_ssl a better player in the buildbots environment. I deep-ended on "try-except-else" clauses. ........ r57518 | neal.norwitz | 2007-08-26 23:40:16 +0200 (Sun, 26 Aug 2007) | 1 line Get the test passing by commenting out some writes (should they be removed?) ........ r57522 | neal.norwitz | 2007-08-27 00:16:23 +0200 (Mon, 27 Aug 2007) | 3 lines Catch IOError for when the device file doesn't exist or the user doesn't have permission to write to the device. ........ r57524 | neal.norwitz | 2007-08-27 00:20:03 +0200 (Mon, 27 Aug 2007) | 5 lines Another patch from Bill Janssen that: 1) Fixes the bug that two class names are initial-lower-case. 2) Replaces the poll waiting for the server to become ready with a threading.Event signal. ........ r57536 | neal.norwitz | 2007-08-27 02:58:33 +0200 (Mon, 27 Aug 2007) | 1 line Stop using string.join (from the module) to ease upgrade to py3k ........ r57537 | neal.norwitz | 2007-08-27 03:03:18 +0200 (Mon, 27 Aug 2007) | 1 line Make a utility function for handling (printing) an error ........ r57538 | neal.norwitz | 2007-08-27 03:15:33 +0200 (Mon, 27 Aug 2007) | 4 lines If we can't create a certificate, print a warning, but don't fail the test. Modified patch from what Bill Janssen sent on python-3000. ........ r57539 | facundo.batista | 2007-08-27 03:15:34 +0200 (Mon, 27 Aug 2007) | 7 lines Ignore test failures caused by 'resource temporarily unavailable' exceptions raised in the test server thread, since SimpleXMLRPCServer does not gracefully handle them. Changed number of requests handled by tests server thread to one (was 2) because no tests require more than one request. [GSoC - Alan McIntyre] ........ r57561 | guido.van.rossum | 2007-08-27 19:19:42 +0200 (Mon, 27 Aug 2007) | 8 lines > Regardless, building a fixed test certificate and checking it in sounds like > the better option. Then the openssl command in the test code can be turned > into a comment describing how the test data was pregenerated. Here's a patch that does that. Bill ........ r57568 | guido.van.rossum | 2007-08-27 20:42:23 +0200 (Mon, 27 Aug 2007) | 26 lines > Some of the code sets the error string in this directly before > returning NULL, and other pieces of the code call PySSL_SetError, > which creates the error string. I think some of the places which set > the string directly probably shouldn't; instead, they should call > PySSL_SetError to cons up the error name directly from the err code. > However, PySSL_SetError only works after the construction of an ssl > object, which means it can't be used there... I'll take a longer look > at it and see if there's a reasonable fix. Here's a patch which addresses this. It also fixes the indentation in PySSL_SetError, bringing it into line with PEP 7, fixes a compile warning about one of the OpenSSL macros, and makes the namespace a bit more consistent. I've tested it on FC 7 and OS X 10.4. % ./python ./Lib/test/regrtest.py -R :1: -u all test_ssl test_ssl beginning 6 repetitions 123456 ...... 1 test OK. [29244 refs] % [GvR: slightly edited to enforce 79-char line length, even if it required violating the style guide.] ........ r57570 | guido.van.rossum | 2007-08-27 21:11:11 +0200 (Mon, 27 Aug 2007) | 2 lines Patch 10124 by Bill Janssen, docs for the new ssl code. ........ r57574 | guido.van.rossum | 2007-08-27 22:51:00 +0200 (Mon, 27 Aug 2007) | 3 lines Patch # 1739906 by Christian Heimes -- add reduce to functools (importing it from __builtin__). ........ r57575 | guido.van.rossum | 2007-08-27 22:52:10 +0200 (Mon, 27 Aug 2007) | 2 lines News about functools.reduce. ........ r57611 | georg.brandl | 2007-08-28 10:29:08 +0200 (Tue, 28 Aug 2007) | 2 lines Document rev. 57574. ........ r57612 | sean.reifschneider | 2007-08-28 11:07:54 +0200 (Tue, 28 Aug 2007) | 2 lines Adding basic imputil documentation. ........ r57614 | georg.brandl | 2007-08-28 12:48:18 +0200 (Tue, 28 Aug 2007) | 2 lines Fix some glitches. ........ r57616 | lars.gustaebel | 2007-08-28 14:31:09 +0200 (Tue, 28 Aug 2007) | 5 lines TarFile.__init__() no longer fails if no name argument is passed and the fileobj argument has no usable name attribute (e.g. StringIO). (will backport to 2.5) ........ r57619 | thomas.wouters | 2007-08-28 17:28:19 +0200 (Tue, 28 Aug 2007) | 22 lines Improve extended slicing support in builtin types and classes. Specifically: - Specialcase extended slices that amount to a shallow copy the same way as is done for simple slices, in the tuple, string and unicode case. - Specialcase step-1 extended slices to optimize the common case for all involved types. - For lists, allow extended slice assignment of differing lengths as long as the step is 1. (Previously, 'l[:2:1] = []' failed even though 'l[:2] = []' and 'l[:2:None] = []' do not.) - Implement extended slicing for buffer, array, structseq, mmap and UserString.UserString. - Implement slice-object support (but not non-step-1 slice assignment) for UserString.MutableString. - Add tests for all new functionality. ........
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``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.
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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.
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.. versionchanged:: 3.1
Added ability to execute packages by looking for a ``__main__`` submodule.
.. versionchanged:: 3.2
Added ``__cached__`` global variable (see :pep:`3147`).
.. versionchanged:: 3.4
Updated to take advantage of the module spec feature added by
:pep:`451`. This allows ``__cached__`` to be set correctly for modules
run this way, as well as ensuring the real module name is always
accessible as ``__spec__.name``.
.. 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__``, ``__spec__``, ``__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` and to ``'<run_path>'`` otherwise.
If the supplied path directly references a script file (whether as source
or as precompiled byte code), then ``__file__`` will be set to the
supplied path, and ``__spec__``, ``__cached__``, ``__loader__`` and
``__package__`` will all be set to :const:`None`.
``__spec__`` will be set to :const:`None` if the supplied path is a
direct path to a script (as source or as precompiled bytecode).
If the supplied path is a reference to a valid sys.path entry, then
``__spec__`` will be set appropriately for the imported ``__main__``
module (that is, ``__spec__.name`` will always be ``__main__``).
``__file__``, ``__cached__``, ``__loader__`` and ``__package__`` will be
:ref:`set as normal <import-mod-attrs>` based on the module spec.
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
.. versionchanged:: 3.4
Updated to take advantage of the module spec feature added by
:pep:`451`. This allows ``__cached__`` to be set correctly in the
case where ``__main__`` is imported from a valid sys.path entry rather
than being executed directly.
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.. 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.
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:pep:`451` - A ModuleSpec Type for the Import System
PEP written and implemented by Eric Snow
:ref:`using-on-general` - CPython command line details
The :func:`importlib.import_module` function