| """runpy.py - locating and running Python code using the module namespace |
| |
| Provides support for locating and running Python scripts using the Python |
| module namespace instead of the native filesystem. |
| |
| This allows Python code to play nicely with non-filesystem based PEP 302 |
| importers when locating support scripts as well as when importing modules. |
| """ |
| # Written by Nick Coghlan <ncoghlan at gmail.com> |
| # to implement PEP 338 (Executing Modules as Scripts) |
| |
| import sys |
| import imp |
| from pkgutil import read_code |
| try: |
| from imp import get_loader |
| except ImportError: |
| from pkgutil import get_loader |
| |
| __all__ = [ |
| "run_module", "run_path", |
| ] |
| |
| class _TempModule(object): |
| """Temporarily replace a module in sys.modules with an empty namespace""" |
| def __init__(self, mod_name): |
| self.mod_name = mod_name |
| self.module = imp.new_module(mod_name) |
| self._saved_module = [] |
| |
| def __enter__(self): |
| mod_name = self.mod_name |
| try: |
| self._saved_module.append(sys.modules[mod_name]) |
| except KeyError: |
| pass |
| sys.modules[mod_name] = self.module |
| return self |
| |
| def __exit__(self, *args): |
| if self._saved_module: |
| sys.modules[self.mod_name] = self._saved_module[0] |
| else: |
| del sys.modules[self.mod_name] |
| self._saved_module = [] |
| |
| class _ModifiedArgv0(object): |
| def __init__(self, value): |
| self.value = value |
| self._saved_value = self._sentinel = object() |
| |
| def __enter__(self): |
| if self._saved_value is not self._sentinel: |
| raise RuntimeError("Already preserving saved value") |
| self._saved_value = sys.argv[0] |
| sys.argv[0] = self.value |
| |
| def __exit__(self, *args): |
| self.value = self._sentinel |
| sys.argv[0] = self._saved_value |
| |
| def _run_code(code, run_globals, init_globals=None, |
| mod_name=None, mod_fname=None, |
| mod_loader=None, pkg_name=None): |
| """Helper to run code in nominated namespace""" |
| if init_globals is not None: |
| run_globals.update(init_globals) |
| run_globals.update(__name__ = mod_name, |
| __file__ = mod_fname, |
| __loader__ = mod_loader, |
| __package__ = pkg_name) |
| exec code in run_globals |
| return run_globals |
| |
| def _run_module_code(code, init_globals=None, |
| mod_name=None, mod_fname=None, |
| mod_loader=None, pkg_name=None): |
| """Helper to run code in new namespace with sys modified""" |
| with _TempModule(mod_name) as temp_module, _ModifiedArgv0(mod_fname): |
| mod_globals = temp_module.module.__dict__ |
| _run_code(code, mod_globals, init_globals, |
| mod_name, mod_fname, mod_loader, pkg_name) |
| # Copy the globals of the temporary module, as they |
| # may be cleared when the temporary module goes away |
| return mod_globals.copy() |
| |
| |
| # This helper is needed due to a missing component in the PEP 302 |
| # loader protocol (specifically, "get_filename" is non-standard) |
| # Since we can't introduce new features in maintenance releases, |
| # support was added to zipimporter under the name '_get_filename' |
| def _get_filename(loader, mod_name): |
| for attr in ("get_filename", "_get_filename"): |
| meth = getattr(loader, attr, None) |
| if meth is not None: |
| return meth(mod_name) |
| return None |
| |
| # Helper to get the loader, code and filename for a module |
| def _get_module_details(mod_name): |
| loader = get_loader(mod_name) |
| if loader is None: |
| raise ImportError("No module named %s" % mod_name) |
| if loader.is_package(mod_name): |
| if mod_name == "__main__" or mod_name.endswith(".__main__"): |
| raise ImportError("Cannot use package as __main__ module") |
| try: |
| pkg_main_name = mod_name + ".__main__" |
| return _get_module_details(pkg_main_name) |
| except ImportError, e: |
| raise ImportError(("%s; %r is a package and cannot " + |
| "be directly executed") %(e, mod_name)) |
| code = loader.get_code(mod_name) |
| if code is None: |
| raise ImportError("No code object available for %s" % mod_name) |
| filename = _get_filename(loader, mod_name) |
| return mod_name, loader, code, filename |
| |
| |
| def _get_main_module_details(): |
| # Helper that gives a nicer error message when attempting to |
| # execute a zipfile or directory by invoking __main__.py |
| main_name = "__main__" |
| try: |
| return _get_module_details(main_name) |
| except ImportError as exc: |
| if main_name in str(exc): |
| raise ImportError("can't find %r module in %r" % |
| (main_name, sys.path[0])) |
| raise |
| |
| # This function is the actual implementation of the -m switch and direct |
| # execution of zipfiles and directories and is deliberately kept private. |
| # This avoids a repeat of the situation where run_module() no longer met the |
| # needs of mainmodule.c, but couldn't be changed because it was public |
| def _run_module_as_main(mod_name, alter_argv=True): |
| """Runs the designated module in the __main__ namespace |
| |
| Note that the executed module will have full access to the |
| __main__ namespace. If this is not desirable, the run_module() |
| function should be used to run the module code in a fresh namespace. |
| |
| At the very least, these variables in __main__ will be overwritten: |
| __name__ |
| __file__ |
| __loader__ |
| __package__ |
| """ |
| try: |
| if alter_argv or mod_name != "__main__": # i.e. -m switch |
| mod_name, loader, code, fname = _get_module_details(mod_name) |
| else: # i.e. directory or zipfile execution |
| mod_name, loader, code, fname = _get_main_module_details() |
| except ImportError as exc: |
| msg = "%s: %s" % (sys.executable, str(exc)) |
| sys.exit(msg) |
| pkg_name = mod_name.rpartition('.')[0] |
| main_globals = sys.modules["__main__"].__dict__ |
| if alter_argv: |
| sys.argv[0] = fname |
| return _run_code(code, main_globals, None, |
| "__main__", fname, loader, pkg_name) |
| |
| def run_module(mod_name, init_globals=None, |
| run_name=None, alter_sys=False): |
| """Execute a module's code without importing it |
| |
| Returns the resulting top level namespace dictionary |
| """ |
| mod_name, loader, code, fname = _get_module_details(mod_name) |
| if run_name is None: |
| run_name = mod_name |
| pkg_name = mod_name.rpartition('.')[0] |
| if alter_sys: |
| return _run_module_code(code, init_globals, run_name, |
| fname, loader, pkg_name) |
| else: |
| # Leave the sys module alone |
| return _run_code(code, {}, init_globals, run_name, |
| fname, loader, pkg_name) |
| |
| |
| # XXX (ncoghlan): Perhaps expose the C API function |
| # as imp.get_importer instead of reimplementing it in Python? |
| def _get_importer(path_name): |
| """Python version of PyImport_GetImporter C API function""" |
| cache = sys.path_importer_cache |
| try: |
| importer = cache[path_name] |
| except KeyError: |
| # Not yet cached. Flag as using the |
| # standard machinery until we finish |
| # checking the hooks |
| cache[path_name] = None |
| for hook in sys.path_hooks: |
| try: |
| importer = hook(path_name) |
| break |
| except ImportError: |
| pass |
| else: |
| # The following check looks a bit odd. The trick is that |
| # NullImporter raises ImportError if the supplied path is a |
| # *valid* directory entry (and hence able to be handled |
| # by the standard import machinery) |
| try: |
| importer = imp.NullImporter(path_name) |
| except ImportError: |
| return None |
| cache[path_name] = importer |
| return importer |
| |
| def _get_code_from_file(fname): |
| # Check for a compiled file first |
| with open(fname, "rb") as f: |
| code = read_code(f) |
| if code is None: |
| # That didn't work, so try it as normal source code |
| with open(fname, "rU") as f: |
| code = compile(f.read(), fname, 'exec') |
| return code |
| |
| def run_path(path_name, init_globals=None, run_name=None): |
| """Execute code located at the specified filesystem location |
| |
| Returns the resulting top level namespace dictionary |
| |
| The file path may refer directly to a Python script (i.e. |
| one that could be directly executed with execfile) or else |
| it may refer to a zipfile or directory containing a top |
| level __main__.py script. |
| """ |
| if run_name is None: |
| run_name = "<run_path>" |
| importer = _get_importer(path_name) |
| if isinstance(importer, imp.NullImporter): |
| # Not a valid sys.path entry, so run the code directly |
| # execfile() doesn't help as we want to allow compiled files |
| code = _get_code_from_file(path_name) |
| return _run_module_code(code, init_globals, run_name, path_name) |
| else: |
| # Importer is defined for path, so add it to |
| # the start of sys.path |
| sys.path.insert(0, path_name) |
| try: |
| # Here's where things are a little different from the run_module |
| # case. There, we only had to replace the module in sys while the |
| # code was running and doing so was somewhat optional. Here, we |
| # have no choice and we have to remove it even while we read the |
| # code. If we don't do this, a __loader__ attribute in the |
| # existing __main__ module may prevent location of the new module. |
| main_name = "__main__" |
| saved_main = sys.modules[main_name] |
| del sys.modules[main_name] |
| try: |
| mod_name, loader, code, fname = _get_main_module_details() |
| finally: |
| sys.modules[main_name] = saved_main |
| pkg_name = "" |
| with _TempModule(run_name) as temp_module, \ |
| _ModifiedArgv0(path_name): |
| mod_globals = temp_module.module.__dict__ |
| return _run_code(code, mod_globals, init_globals, |
| run_name, fname, loader, pkg_name).copy() |
| finally: |
| try: |
| sys.path.remove(path_name) |
| except ValueError: |
| pass |
| |
| |
| if __name__ == "__main__": |
| # Run the module specified as the next command line argument |
| if len(sys.argv) < 2: |
| print >> sys.stderr, "No module specified for execution" |
| else: |
| del sys.argv[0] # Make the requested module sys.argv[0] |
| _run_module_as_main(sys.argv[0]) |
