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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 importlib.machinery # importlib first so we can test #15386 via -m |
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import importlib.util |
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import io |
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import types |
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import os |
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from pkgutil import read_code, get_importer |
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__all__ = [ |
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"run_module", "run_path", |
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] |
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class _TempModule(object): |
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"""Temporarily replace a module in sys.modules with an empty namespace""" |
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def __init__(self, mod_name): |
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self.mod_name = mod_name |
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self.module = types.ModuleType(mod_name) |
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self._saved_module = [] |
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def __enter__(self): |
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mod_name = self.mod_name |
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try: |
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self._saved_module.append(sys.modules[mod_name]) |
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except KeyError: |
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pass |
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sys.modules[mod_name] = self.module |
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return self |
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def __exit__(self, *args): |
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if self._saved_module: |
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sys.modules[self.mod_name] = self._saved_module[0] |
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else: |
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del sys.modules[self.mod_name] |
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self._saved_module = [] |
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class _ModifiedArgv0(object): |
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def __init__(self, value): |
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self.value = value |
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self._saved_value = self._sentinel = object() |
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def __enter__(self): |
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if self._saved_value is not self._sentinel: |
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raise RuntimeError("Already preserving saved value") |
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self._saved_value = sys.argv[0] |
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sys.argv[0] = self.value |
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def __exit__(self, *args): |
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self.value = self._sentinel |
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sys.argv[0] = self._saved_value |
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# TODO: Replace these helpers with importlib._bootstrap_external functions. |
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def _run_code(code, run_globals, init_globals=None, |
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mod_name=None, mod_spec=None, |
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pkg_name=None, script_name=None): |
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"""Helper to run code in nominated namespace""" |
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if init_globals is not None: |
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run_globals.update(init_globals) |
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if mod_spec is None: |
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loader = None |
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fname = script_name |
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cached = None |
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else: |
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loader = mod_spec.loader |
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fname = mod_spec.origin |
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cached = mod_spec.cached |
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if pkg_name is None: |
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pkg_name = mod_spec.parent |
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run_globals.update(__name__ = mod_name, |
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__file__ = fname, |
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__cached__ = cached, |
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__doc__ = None, |
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__loader__ = loader, |
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__package__ = pkg_name, |
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__spec__ = mod_spec) |
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exec(code, 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_spec=None, |
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pkg_name=None, script_name=None): |
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"""Helper to run code in new namespace with sys modified""" |
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fname = script_name if mod_spec is None else mod_spec.origin |
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with _TempModule(mod_name) as temp_module, _ModifiedArgv0(fname): |
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mod_globals = temp_module.module.__dict__ |
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_run_code(code, mod_globals, init_globals, |
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mod_name, mod_spec, pkg_name, script_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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# Helper to get the full name, spec and code for a module |
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def _get_module_details(mod_name, error=ImportError): |
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if mod_name.startswith("."): |
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raise error("Relative module names not supported") |
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pkg_name, _, _ = mod_name.rpartition(".") |
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if pkg_name: |
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# Try importing the parent to avoid catching initialization errors |
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try: |
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__import__(pkg_name) |
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except ImportError as e: |
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# If the parent or higher ancestor package is missing, let the |
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# error be raised by find_spec() below and then be caught. But do |
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# not allow other errors to be caught. |
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if e.name is None or (e.name != pkg_name and |
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not pkg_name.startswith(e.name + ".")): |
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raise |
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# Warn if the module has already been imported under its normal name |
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existing = sys.modules.get(mod_name) |
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if existing is not None and not hasattr(existing, "__path__"): |
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from warnings import warn |
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msg = "{mod_name!r} found in sys.modules after import of " \ |
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"package {pkg_name!r}, but prior to execution of " \ |
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"{mod_name!r}; this may result in unpredictable " \ |
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"behaviour".format(mod_name=mod_name, pkg_name=pkg_name) |
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warn(RuntimeWarning(msg)) |
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try: |
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spec = importlib.util.find_spec(mod_name) |
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except (ImportError, AttributeError, TypeError, ValueError) as ex: |
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# This hack fixes an impedance mismatch between pkgutil and |
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# importlib, where the latter raises other errors for cases where |
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# pkgutil previously raised ImportError |
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msg = "Error while finding module specification for {!r} ({}: {})" |
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if mod_name.endswith(".py"): |
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msg += (f". Try using '{mod_name[:-3]}' instead of " |
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f"'{mod_name}' as the module name.") |
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raise error(msg.format(mod_name, type(ex).__name__, ex)) from ex |
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if spec is None: |
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raise error("No module named %s" % mod_name) |
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if spec.submodule_search_locations is not None: |
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if mod_name == "__main__" or mod_name.endswith(".__main__"): |
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raise error("Cannot use package as __main__ module") |
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try: |
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pkg_main_name = mod_name + ".__main__" |
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return _get_module_details(pkg_main_name, error) |
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except error as e: |
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if mod_name not in sys.modules: |
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raise # No module loaded; being a package is irrelevant |
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raise error(("%s; %r is a package and cannot " + |
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"be directly executed") %(e, mod_name)) |
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loader = spec.loader |
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if loader is None: |
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raise error("%r is a namespace package and cannot be executed" |
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% mod_name) |
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try: |
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code = loader.get_code(mod_name) |
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except ImportError as e: |
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raise error(format(e)) from e |
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if code is None: |
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raise error("No code object available for %s" % mod_name) |
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return mod_name, spec, code |
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class _Error(Exception): |
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"""Error that _run_module_as_main() should report without a traceback""" |
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# XXX ncoghlan: Should this be documented and made public? |
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# (Current thoughts: don't repeat the mistake that lead to its |
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# creation when run_module() no longer met the needs of |
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# mainmodule.c, but couldn't be changed because it was public) |
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def _run_module_as_main(mod_name, alter_argv=True): |
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"""Runs the designated module in the __main__ namespace |
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Note that the executed module will have full access to the |
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__main__ namespace. If this is not desirable, the run_module() |
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function should be used to run the module code in a fresh namespace. |
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At the very least, these variables in __main__ will be overwritten: |
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__name__ |
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__file__ |
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__cached__ |
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__loader__ |
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__package__ |
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""" |
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try: |
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if alter_argv or mod_name != "__main__": # i.e. -m switch |
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mod_name, mod_spec, code = _get_module_details(mod_name, _Error) |
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else: # i.e. directory or zipfile execution |
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mod_name, mod_spec, code = _get_main_module_details(_Error) |
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except _Error as exc: |
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msg = "%s: %s" % (sys.executable, exc) |
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sys.exit(msg) |
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main_globals = sys.modules["__main__"].__dict__ |
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if alter_argv: |
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sys.argv[0] = mod_spec.origin |
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return _run_code(code, main_globals, None, |
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"__main__", mod_spec) |
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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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mod_name -- an absolute module name or package name. |
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Optional arguments: |
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init_globals -- dictionary used to pre-populate the module’s |
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globals dictionary before the code is executed. |
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run_name -- if not None, this will be used for setting __name__; |
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otherwise, __name__ will be set to mod_name + '__main__' if the |
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named module is a package and to just mod_name otherwise. |
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alter_sys -- if True, sys.argv[0] is updated with the value of |
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__file__ and sys.modules[__name__] is updated with a temporary |
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module object for the module being executed. Both are |
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restored to their original values before the function returns. |
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Returns the resulting module globals dictionary. |
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""" |
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mod_name, mod_spec, code = _get_module_details(mod_name) |
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if run_name is None: |
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run_name = mod_name |
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if alter_sys: |
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return _run_module_code(code, init_globals, run_name, mod_spec) |
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else: |
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# Leave the sys module alone |
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return _run_code(code, {}, init_globals, run_name, mod_spec) |
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def _get_main_module_details(error=ImportError): |
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# Helper that gives a nicer error message when attempting to |
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# execute a zipfile or directory by invoking __main__.py |
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# Also moves the standard __main__ out of the way so that the |
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# preexisting __loader__ entry doesn't cause issues |
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main_name = "__main__" |
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saved_main = sys.modules[main_name] |
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del sys.modules[main_name] |
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try: |
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return _get_module_details(main_name) |
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except ImportError as exc: |
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if main_name in str(exc): |
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raise error("can't find %r module in %r" % |
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(main_name, sys.path[0])) from exc |
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raise |
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finally: |
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sys.modules[main_name] = saved_main |
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def _get_code_from_file(run_name, fname): |
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# Check for a compiled file first |
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decoded_path = os.path.abspath(os.fsdecode(fname)) |
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with io.open_code(decoded_path) as f: |
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code = read_code(f) |
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if code is None: |
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# That didn't work, so try it as normal source code |
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with io.open_code(decoded_path) as f: |
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code = compile(f.read(), fname, 'exec') |
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return code, fname |
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def run_path(path_name, init_globals=None, run_name=None): |
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"""Execute code located at the specified filesystem location. |
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path_name -- filesystem location of a Python script, zipfile, |
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or directory containing a top level __main__.py script. |
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Optional arguments: |
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init_globals -- dictionary used to pre-populate the module’s |
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globals dictionary before the code is executed. |
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run_name -- if not None, this will be used to set __name__; |
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otherwise, '<run_path>' will be used for __name__. |
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Returns the resulting module globals dictionary. |
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""" |
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if run_name is None: |
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run_name = "<run_path>" |
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pkg_name = run_name.rpartition(".")[0] |
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importer = get_importer(path_name) |
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# Trying to avoid importing imp so as to not consume the deprecation warning. |
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is_NullImporter = False |
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if type(importer).__module__ == 'imp': |
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if type(importer).__name__ == 'NullImporter': |
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is_NullImporter = True |
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if isinstance(importer, type(None)) or is_NullImporter: |
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# Not a valid sys.path entry, so run the code directly |
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# execfile() doesn't help as we want to allow compiled files |
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code, fname = _get_code_from_file(run_name, path_name) |
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return _run_module_code(code, init_globals, run_name, |
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pkg_name=pkg_name, script_name=fname) |
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else: |
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# Finder is defined for path, so add it to |
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# the start of sys.path |
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sys.path.insert(0, path_name) |
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try: |
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# Here's where things are a little different from the run_module |
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# case. There, we only had to replace the module in sys while the |
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# code was running and doing so was somewhat optional. Here, we |
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# have no choice and we have to remove it even while we read the |
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# code. If we don't do this, a __loader__ attribute in the |
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# existing __main__ module may prevent location of the new module. |
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mod_name, mod_spec, code = _get_main_module_details() |
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with _TempModule(run_name) as temp_module, \ |
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_ModifiedArgv0(path_name): |
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mod_globals = temp_module.module.__dict__ |
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return _run_code(code, mod_globals, init_globals, |
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run_name, mod_spec, pkg_name).copy() |
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finally: |
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try: |
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sys.path.remove(path_name) |
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except ValueError: |
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pass |
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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("No module specified for execution", file=sys.stderr) |
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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_as_main(sys.argv[0]) |