105 lines
3.5 KiB
Python
105 lines
3.5 KiB
Python
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"""runpy.py - locating and running Python code using the module namespace
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Provides support for locating and running Python scripts using the Python
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module namespace instead of the native filesystem.
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This allows Python code to play nicely with non-filesystem based PEP 302
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importers when locating support scripts as well as when importing modules.
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"""
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# Written by Nick Coghlan <ncoghlan at gmail.com>
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# to implement PEP 338 (Executing Modules as Scripts)
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import sys
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import imp
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try:
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from imp import get_loader
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except ImportError:
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from pkgutil import get_loader
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__all__ = [
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"run_module",
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]
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def _run_code(code, run_globals, init_globals,
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mod_name, mod_fname, mod_loader):
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"""Helper for _run_module_code"""
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if init_globals is not None:
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run_globals.update(init_globals)
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run_globals.update(__name__ = mod_name,
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__file__ = mod_fname,
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__loader__ = mod_loader)
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exec code in run_globals
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return run_globals
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def _run_module_code(code, init_globals=None,
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mod_name=None, mod_fname=None,
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mod_loader=None, alter_sys=False):
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"""Helper for run_module"""
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# Set up the top level namespace dictionary
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if alter_sys:
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# Modify sys.argv[0] and sys.module[mod_name]
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temp_module = imp.new_module(mod_name)
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mod_globals = temp_module.__dict__
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saved_argv0 = sys.argv[0]
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restore_module = mod_name in sys.modules
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if restore_module:
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saved_module = sys.modules[mod_name]
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sys.argv[0] = mod_fname
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sys.modules[mod_name] = temp_module
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try:
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_run_code(code, mod_globals, init_globals,
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mod_name, mod_fname, mod_loader)
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finally:
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sys.argv[0] = saved_argv0
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if restore_module:
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sys.modules[mod_name] = saved_module
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else:
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del sys.modules[mod_name]
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# Copy the globals of the temporary module, as they
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# may be cleared when the temporary module goes away
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return mod_globals.copy()
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else:
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# Leave the sys module alone
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return _run_code(code, {}, init_globals,
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mod_name, mod_fname, mod_loader)
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# This helper is needed due to a missing component in the PEP 302
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# loader protocol (specifically, "get_filename" is non-standard)
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def _get_filename(loader, mod_name):
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try:
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get_filename = loader.get_filename
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except AttributeError:
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return None
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else:
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return get_filename(mod_name)
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def run_module(mod_name, init_globals=None,
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run_name=None, alter_sys=False):
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"""Execute a module's code without importing it
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Returns the resulting top level namespace dictionary
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"""
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loader = get_loader(mod_name)
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if loader is None:
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raise ImportError("No module named " + mod_name)
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code = loader.get_code(mod_name)
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if code is None:
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raise ImportError("No code object available for " + mod_name)
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filename = _get_filename(loader, mod_name)
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if run_name is None:
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run_name = mod_name
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return _run_module_code(code, init_globals, run_name,
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filename, loader, alter_sys)
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if __name__ == "__main__":
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# Run the module specified as the next command line argument
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if len(sys.argv) < 2:
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print >> sys.stderr, "No module specified for execution"
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else:
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del sys.argv[0] # Make the requested module sys.argv[0]
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run_module(sys.argv[0], run_name="__main__", alter_sys=True)
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