| 1 | """runpy.py - locating and running Python code using the module namespace
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| 2 |
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| 3 | Provides support for locating and running Python scripts using the Python
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| 4 | module namespace instead of the native filesystem.
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| 5 |
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| 6 | This allows Python code to play nicely with non-filesystem based PEP 302
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| 7 | importers when locating support scripts as well as when importing modules.
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| 8 | """
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| 9 | # Written by Nick Coghlan <ncoghlan at gmail.com>
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| 10 | # to implement PEP 338 (Executing Modules as Scripts)
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| 11 |
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| 12 | import sys
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| 13 | import imp
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| 14 | from pkgutil import read_code
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| 15 | try:
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| 16 | from imp import get_loader
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| 17 | except ImportError:
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| 18 | from pkgutil import get_loader
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| 19 |
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| 20 | __all__ = [
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| 21 | "run_module", "run_path",
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| 22 | ]
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| 23 |
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| 24 | class _TempModule(object):
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| 25 | """Temporarily replace a module in sys.modules with an empty namespace"""
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| 26 | def __init__(self, mod_name):
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| 27 | self.mod_name = mod_name
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| 28 | self.module = imp.new_module(mod_name)
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| 29 | self._saved_module = []
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| 30 |
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| 31 | def __enter__(self):
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| 32 | mod_name = self.mod_name
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| 33 | try:
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| 34 | self._saved_module.append(sys.modules[mod_name])
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| 35 | except KeyError:
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| 36 | pass
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| 37 | sys.modules[mod_name] = self.module
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| 38 | return self
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| 39 |
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| 40 | def __exit__(self, *args):
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| 41 | if self._saved_module:
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| 42 | sys.modules[self.mod_name] = self._saved_module[0]
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| 43 | else:
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| 44 | del sys.modules[self.mod_name]
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| 45 | self._saved_module = []
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| 46 |
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| 47 | class _ModifiedArgv0(object):
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| 48 | def __init__(self, value):
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| 49 | self.value = value
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| 50 | self._saved_value = self._sentinel = object()
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| 51 |
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| 52 | def __enter__(self):
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| 53 | if self._saved_value is not self._sentinel:
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| 54 | raise RuntimeError("Already preserving saved value")
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| 55 | self._saved_value = sys.argv[0]
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| 56 | sys.argv[0] = self.value
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| 57 |
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| 58 | def __exit__(self, *args):
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| 59 | self.value = self._sentinel
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| 60 | sys.argv[0] = self._saved_value
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| 61 |
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| 62 | def _run_code(code, run_globals, init_globals=None,
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| 63 | mod_name=None, mod_fname=None,
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| 64 | mod_loader=None, pkg_name=None):
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| 65 | """Helper to run code in nominated namespace"""
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| 66 | if init_globals is not None:
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| 67 | run_globals.update(init_globals)
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| 68 | run_globals.update(__name__ = mod_name,
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| 69 | __file__ = mod_fname,
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| 70 | __loader__ = mod_loader,
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| 71 | __package__ = pkg_name)
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| 72 | exec code in run_globals
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| 73 | return run_globals
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| 74 |
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| 75 | def _run_module_code(code, init_globals=None,
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| 76 | mod_name=None, mod_fname=None,
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| 77 | mod_loader=None, pkg_name=None):
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| 78 | """Helper to run code in new namespace with sys modified"""
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| 79 | with _TempModule(mod_name) as temp_module, _ModifiedArgv0(mod_fname):
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| 80 | mod_globals = temp_module.module.__dict__
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| 81 | _run_code(code, mod_globals, init_globals,
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| 82 | mod_name, mod_fname, mod_loader, pkg_name)
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| 83 | # Copy the globals of the temporary module, as they
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| 84 | # may be cleared when the temporary module goes away
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| 85 | return mod_globals.copy()
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| 86 |
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| 87 |
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| 88 | # This helper is needed due to a missing component in the PEP 302
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| 89 | # loader protocol (specifically, "get_filename" is non-standard)
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| 90 | # Since we can't introduce new features in maintenance releases,
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| 91 | # support was added to zipimporter under the name '_get_filename'
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| 92 | def _get_filename(loader, mod_name):
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| 93 | for attr in ("get_filename", "_get_filename"):
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| 94 | meth = getattr(loader, attr, None)
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| 95 | if meth is not None:
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| 96 | return meth(mod_name)
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| 97 | return None
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| 98 |
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| 99 | # Helper to get the loader, code and filename for a module
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| 100 | def _get_module_details(mod_name, error=ImportError):
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| 101 | try:
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| 102 | loader = get_loader(mod_name)
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| 103 | if loader is None:
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| 104 | raise error("No module named %s" % mod_name)
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| 105 | ispkg = loader.is_package(mod_name)
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| 106 | except ImportError as e:
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| 107 | raise error(format(e))
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| 108 | if ispkg:
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| 109 | if mod_name == "__main__" or mod_name.endswith(".__main__"):
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| 110 | raise error("Cannot use package as __main__ module")
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| 111 | __import__(mod_name) # Do not catch exceptions initializing package
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| 112 | try:
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| 113 | pkg_main_name = mod_name + ".__main__"
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| 114 | return _get_module_details(pkg_main_name)
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| 115 | except ImportError, e:
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| 116 | raise error(("%s; %r is a package and cannot " +
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| 117 | "be directly executed") %(e, mod_name))
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| 118 | try:
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| 119 | code = loader.get_code(mod_name)
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| 120 | except ImportError as e:
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| 121 | raise error(format(e))
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| 122 | if code is None:
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| 123 | raise error("No code object available for %s" % mod_name)
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| 124 | filename = _get_filename(loader, mod_name)
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| 125 | return mod_name, loader, code, filename
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| 126 |
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| 127 |
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| 128 | def _get_main_module_details(error=ImportError):
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| 129 | # Helper that gives a nicer error message when attempting to
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| 130 | # execute a zipfile or directory by invoking __main__.py
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| 131 | main_name = "__main__"
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| 132 | try:
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| 133 | return _get_module_details(main_name)
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| 134 | except ImportError as exc:
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| 135 | if main_name in str(exc):
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| 136 | raise error("can't find %r module in %r" %
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| 137 | (main_name, sys.path[0]))
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| 138 | raise
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| 139 |
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| 140 | class _Error(Exception):
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| 141 | """Error that _run_module_as_main() should report without a traceback"""
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| 142 |
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| 143 | # This function is the actual implementation of the -m switch and direct
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| 144 | # execution of zipfiles and directories and is deliberately kept private.
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| 145 | # This avoids a repeat of the situation where run_module() no longer met the
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| 146 | # needs of mainmodule.c, but couldn't be changed because it was public
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| 147 | def _run_module_as_main(mod_name, alter_argv=True):
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| 148 | """Runs the designated module in the __main__ namespace
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| 149 |
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| 150 | Note that the executed module will have full access to the
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| 151 | __main__ namespace. If this is not desirable, the run_module()
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| 152 | function should be used to run the module code in a fresh namespace.
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| 153 |
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| 154 | At the very least, these variables in __main__ will be overwritten:
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| 155 | __name__
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| 156 | __file__
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| 157 | __loader__
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| 158 | __package__
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| 159 | """
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| 160 | try:
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| 161 | if alter_argv or mod_name != "__main__": # i.e. -m switch
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| 162 | mod_name, loader, code, fname = _get_module_details(
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| 163 | mod_name, _Error)
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| 164 | else: # i.e. directory or zipfile execution
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| 165 | mod_name, loader, code, fname = _get_main_module_details(_Error)
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| 166 | except _Error as exc:
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| 167 | msg = "%s: %s" % (sys.executable, exc)
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| 168 | sys.exit(msg)
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| 169 | pkg_name = mod_name.rpartition('.')[0]
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| 170 | main_globals = sys.modules["__main__"].__dict__
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| 171 | if alter_argv:
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| 172 | sys.argv[0] = fname
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| 173 | return _run_code(code, main_globals, None,
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| 174 | "__main__", fname, loader, pkg_name)
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| 175 |
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| 176 | def run_module(mod_name, init_globals=None,
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| 177 | run_name=None, alter_sys=False):
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| 178 | """Execute a module's code without importing it
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| 179 |
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| 180 | Returns the resulting top level namespace dictionary
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| 181 | """
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| 182 | mod_name, loader, code, fname = _get_module_details(mod_name)
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| 183 | if run_name is None:
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| 184 | run_name = mod_name
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| 185 | pkg_name = mod_name.rpartition('.')[0]
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| 186 | if alter_sys:
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| 187 | return _run_module_code(code, init_globals, run_name,
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| 188 | fname, loader, pkg_name)
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| 189 | else:
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| 190 | # Leave the sys module alone
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| 191 | return _run_code(code, {}, init_globals, run_name,
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| 192 | fname, loader, pkg_name)
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| 193 |
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| 194 |
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| 195 | # XXX (ncoghlan): Perhaps expose the C API function
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| 196 | # as imp.get_importer instead of reimplementing it in Python?
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| 197 | def _get_importer(path_name):
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| 198 | """Python version of PyImport_GetImporter C API function"""
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| 199 | cache = sys.path_importer_cache
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| 200 | try:
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| 201 | importer = cache[path_name]
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| 202 | except KeyError:
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| 203 | # Not yet cached. Flag as using the
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| 204 | # standard machinery until we finish
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| 205 | # checking the hooks
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| 206 | cache[path_name] = None
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| 207 | for hook in sys.path_hooks:
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| 208 | try:
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| 209 | importer = hook(path_name)
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| 210 | break
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| 211 | except ImportError:
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| 212 | pass
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| 213 | else:
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| 214 | # The following check looks a bit odd. The trick is that
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| 215 | # NullImporter raises ImportError if the supplied path is a
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| 216 | # *valid* directory entry (and hence able to be handled
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| 217 | # by the standard import machinery)
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| 218 | try:
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| 219 | importer = imp.NullImporter(path_name)
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| 220 | except ImportError:
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| 221 | return None
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| 222 | cache[path_name] = importer
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| 223 | return importer
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| 224 |
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| 225 | def _get_code_from_file(fname):
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| 226 | # Check for a compiled file first
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| 227 | with open(fname, "rb") as f:
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| 228 | code = read_code(f)
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| 229 | if code is None:
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| 230 | # That didn't work, so try it as normal source code
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| 231 | with open(fname, "rU") as f:
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| 232 | code = compile(f.read(), fname, 'exec')
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| 233 | return code
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| 234 |
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| 235 | def run_path(path_name, init_globals=None, run_name=None):
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| 236 | """Execute code located at the specified filesystem location
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| 237 |
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| 238 | Returns the resulting top level namespace dictionary
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| 239 |
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| 240 | The file path may refer directly to a Python script (i.e.
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| 241 | one that could be directly executed with execfile) or else
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| 242 | it may refer to a zipfile or directory containing a top
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| 243 | level __main__.py script.
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| 244 | """
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| 245 | if run_name is None:
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| 246 | run_name = "<run_path>"
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| 247 | importer = _get_importer(path_name)
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| 248 | if isinstance(importer, imp.NullImporter):
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| 249 | # Not a valid sys.path entry, so run the code directly
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| 250 | # execfile() doesn't help as we want to allow compiled files
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| 251 | code = _get_code_from_file(path_name)
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| 252 | return _run_module_code(code, init_globals, run_name, path_name)
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| 253 | else:
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| 254 | # Importer is defined for path, so add it to
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| 255 | # the start of sys.path
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| 256 | sys.path.insert(0, path_name)
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| 257 | try:
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| 258 | # Here's where things are a little different from the run_module
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| 259 | # case. There, we only had to replace the module in sys while the
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| 260 | # code was running and doing so was somewhat optional. Here, we
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| 261 | # have no choice and we have to remove it even while we read the
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| 262 | # code. If we don't do this, a __loader__ attribute in the
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| 263 | # existing __main__ module may prevent location of the new module.
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| 264 | main_name = "__main__"
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| 265 | saved_main = sys.modules[main_name]
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| 266 | del sys.modules[main_name]
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| 267 | try:
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| 268 | mod_name, loader, code, fname = _get_main_module_details()
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| 269 | finally:
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| 270 | sys.modules[main_name] = saved_main
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| 271 | pkg_name = ""
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| 272 | with _TempModule(run_name) as temp_module, \
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| 273 | _ModifiedArgv0(path_name):
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| 274 | mod_globals = temp_module.module.__dict__
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| 275 | return _run_code(code, mod_globals, init_globals,
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| 276 | run_name, fname, loader, pkg_name).copy()
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| 277 | finally:
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| 278 | try:
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| 279 | sys.path.remove(path_name)
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| 280 | except ValueError:
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| 281 | pass
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| 282 |
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| 283 |
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| 284 | if __name__ == "__main__":
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| 285 | # Run the module specified as the next command line argument
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| 286 | if len(sys.argv) < 2:
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| 287 | print >> sys.stderr, "No module specified for execution"
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| 288 | else:
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| 289 | del sys.argv[0] # Make the requested module sys.argv[0]
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| 290 | _run_module_as_main(sys.argv[0])
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