New in version 2.5.
The runpy module is used to locate and run Python modules without importing them first. Its main use is to implement the -m command line switch that allows scripts to be located using the Python module namespace rather than the filesystem.
When executed as a script, the module effectively operates as follows:
del sys.argv # Remove the runpy module from the arguments run_module(sys.argv, run_name="__main__", alter_sys=True)
The runpy module provides a single function:
|mod_name[, init_globals] [, run_name][, alter_sys])|
The optional dictionary argument init_globals may be used to
pre-populate the 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 the
The special global variables
__builtins__ are set in the globals
dictionary before the module code is executed.
__name__ is set to run_name if this optional argument is
supplied, and the mod_name argument otherwise.
__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).
__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
__builtins__ is automatically initialised with a reference to
the top level namespace of the __builtin__ module.
If the argument alter_sys is supplied and evaluates to
sys.argv is updated with the value of
sys.modules[__name__] is updated with a
temporary module object for the module being executed. Both
sys.modules[__name__] are restored to
their original values before the function returns.
Note that this manipulation of 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 sys module be left alone when invoking this function from threaded code.
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