1 :mod:`runpy` --- Locating and executing Python modules 2 ====================================================== 3 4 .. module:: runpy 5 :synopsis: Locate and run Python modules without importing them first. 6 .. moduleauthor:: Nick Coghlan <ncoghlan (a] gmail.com> 7 8 9 .. versionadded:: 2.5 10 11 **Source code:** :source:`Lib/runpy.py` 12 13 -------------- 14 15 The :mod:`runpy` module is used to locate and run Python modules without 16 importing them first. Its main use is to implement the :option:`-m` command 17 line switch that allows scripts to be located using the Python module 18 namespace rather than the filesystem. 19 20 The :mod:`runpy` module provides two functions: 21 22 23 .. function:: run_module(mod_name, init_globals=None, run_name=None, alter_sys=False) 24 25 .. index:: 26 module: __main__ 27 28 Execute the code of the specified module and return the resulting module 29 globals dictionary. The module's code is first located using the standard 30 import mechanism (refer to :pep:`302` for details) and then executed in a 31 fresh module namespace. 32 33 If the supplied module name refers to a package rather than a normal 34 module, then that package is imported and the ``__main__`` submodule within 35 that package is then executed and the resulting module globals dictionary 36 returned. 37 38 The optional dictionary argument *init_globals* may be used to pre-populate 39 the module's globals dictionary before the code is executed. The supplied 40 dictionary will not be modified. If any of the special global variables 41 below are defined in the supplied dictionary, those definitions are 42 overridden by :func:`run_module`. 43 44 The special global variables ``__name__``, ``__file__``, ``__loader__`` 45 and ``__package__`` are set in the globals dictionary before the module 46 code is executed (Note that this is a minimal set of variables - other 47 variables may be set implicitly as an interpreter implementation detail). 48 49 ``__name__`` is set to *run_name* if this optional argument is not 50 :const:`None`, to ``mod_name + '.__main__'`` if the named module is a 51 package and to the *mod_name* argument otherwise. 52 53 ``__file__`` is set to the name provided by the module loader. If the 54 loader does not make filename information available, this variable is set 55 to :const:`None`. 56 57 ``__loader__`` is set to the :pep:`302` module loader used to retrieve the 58 code for the module (This loader may be a wrapper around the standard 59 import mechanism). 60 61 ``__package__`` is set to *mod_name* if the named module is a package and 62 to ``mod_name.rpartition('.')[0]`` otherwise. 63 64 If the argument *alter_sys* is supplied and evaluates to :const:`True`, 65 then ``sys.argv[0]`` is updated with the value of ``__file__`` and 66 ``sys.modules[__name__]`` is updated with a temporary module object for the 67 module being executed. Both ``sys.argv[0]`` and ``sys.modules[__name__]`` 68 are restored to their original values before the function returns. 69 70 Note that this manipulation of :mod:`sys` is not thread-safe. Other threads 71 may see the partially initialised module, as well as the altered list of 72 arguments. It is recommended that the :mod:`sys` module be left alone when 73 invoking this function from threaded code. 74 75 .. seealso:: 76 The :option:`-m` option offering equivalent functionality from the 77 command line. 78 79 .. versionchanged:: 2.7 80 Added ability to execute packages by looking for a ``__main__`` 81 submodule 82 83 84 .. function:: run_path(file_path, init_globals=None, run_name=None) 85 86 .. index:: 87 module: __main__ 88 89 Execute the code at the named filesystem location and return the resulting 90 module globals dictionary. As with a script name supplied to the CPython 91 command line, the supplied path may refer to a Python source file, a 92 compiled bytecode file or a valid sys.path entry containing a ``__main__`` 93 module (e.g. a zipfile containing a top-level ``__main__.py`` file). 94 95 For a simple script, the specified code is simply executed in a fresh 96 module namespace. For a valid sys.path entry (typically a zipfile or 97 directory), the entry is first added to the beginning of ``sys.path``. The 98 function then looks for and executes a :mod:`__main__` module using the 99 updated path. Note that there is no special protection against invoking 100 an existing :mod:`__main__` entry located elsewhere on ``sys.path`` if 101 there is no such module at the specified location. 102 103 The optional dictionary argument *init_globals* may be used to pre-populate 104 the module's globals dictionary before the code is executed. The supplied 105 dictionary will not be modified. If any of the special global variables 106 below are defined in the supplied dictionary, those definitions are 107 overridden by :func:`run_path`. 108 109 The special global variables ``__name__``, ``__file__``, ``__loader__`` 110 and ``__package__`` are set in the globals dictionary before the module 111 code is executed (Note that this is a minimal set of variables - other 112 variables may be set implicitly as an interpreter implementation detail). 113 114 ``__name__`` is set to *run_name* if this optional argument is not 115 :const:`None` and to ``'<run_path>'`` otherwise. 116 117 ``__file__`` is set to the name provided by the module loader. If the 118 loader does not make filename information available, this variable is set 119 to :const:`None`. For a simple script, this will be set to ``file_path``. 120 121 ``__loader__`` is set to the :pep:`302` module loader used to retrieve the 122 code for the module (This loader may be a wrapper around the standard 123 import mechanism). For a simple script, this will be set to :const:`None`. 124 125 ``__package__`` is set to ``__name__.rpartition('.')[0]``. 126 127 A number of alterations are also made to the :mod:`sys` module. Firstly, 128 ``sys.path`` may be altered as described above. ``sys.argv[0]`` is updated 129 with the value of ``file_path`` and ``sys.modules[__name__]`` is updated 130 with a temporary module object for the module being executed. All 131 modifications to items in :mod:`sys` are reverted before the function 132 returns. 133 134 Note that, unlike :func:`run_module`, the alterations made to :mod:`sys` 135 are not optional in this function as these adjustments are essential to 136 allowing the execution of sys.path entries. As the thread-safety 137 limitations still apply, use of this function in threaded code should be 138 either serialised with the import lock or delegated to a separate process. 139 140 .. seealso:: 141 :ref:`using-on-interface-options` for equivalent functionality on the 142 command line (``python path/to/script``). 143 144 .. versionadded:: 2.7 145 146 .. seealso:: 147 148 :pep:`338` -- Executing modules as scripts 149 PEP written and implemented by Nick Coghlan. 150 151 :pep:`366` -- Main module explicit relative imports 152 PEP written and implemented by Nick Coghlan. 153 154 :ref:`using-on-general` - CPython command line details 155
