Refactor importlib.__import__() and _gcd_import() to facilitate using
an __import__ implementation that takes care of basics in C and punts to importlib for more complicated code.
This commit is contained in:
Brett Cannon
parent
292f9a891d
commit
7fab676e87
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@ -861,6 +861,84 @@ class _ImportLockContext:
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imp.release_lock()
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def _resolve_name(name, package, level):
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"""Resolve a relative module name to an absolute one."""
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dot = len(package)
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for x in range(level, 1, -1):
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try:
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dot = package.rindex('.', 0, dot)
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except ValueError:
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raise ValueError("attempted relative import beyond "
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"top-level package")
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if name:
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return "{0}.{1}".format(package[:dot], name)
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else:
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return package[:dot]
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def _find_module(name, path):
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"""Find a module's loader."""
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meta_path = sys.meta_path + _IMPLICIT_META_PATH
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for finder in meta_path:
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loader = finder.find_module(name, path)
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if loader is not None:
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# The parent import may have already imported this module.
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if name not in sys.modules:
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return loader
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else:
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return sys.modules[name].__loader__
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else:
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return None
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def _set___package__(module):
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"""Set __package__ on a module."""
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# Watch out for what comes out of sys.modules to not be a module,
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# e.g. an int.
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try:
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module.__package__ = module.__name__
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if not hasattr(module, '__path__'):
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module.__package__ = module.__package__.rpartition('.')[0]
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except AttributeError:
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pass
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def _sanity_check(name, package, level):
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"""Verify arguments are "sane"."""
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if package:
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if not hasattr(package, 'rindex'):
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raise ValueError("__package__ not set to a string")
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elif package not in sys.modules:
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msg = ("Parent module {0!r} not loaded, cannot perform relative "
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"import")
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raise SystemError(msg.format(package))
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if not name and level == 0:
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raise ValueError("Empty module name")
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def _find_search_path(name, import_):
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"""Find the search path for a module.
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import_ is expected to be a callable which takes the name of a module to
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import. It is required to decouple the function from importlib.
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"""
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path = None
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parent = name.rpartition('.')[0]
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if parent:
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if parent not in sys.modules:
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import_(parent)
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# Backwards-compatibility; be nicer to skip the dict lookup.
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parent_module = sys.modules[parent]
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try:
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path = parent_module.__path__
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except AttributeError:
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msg = (_ERR_MSG + '; {} is not a package').format(name, parent)
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raise ImportError(msg)
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return parent, path
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_IMPLICIT_META_PATH = [BuiltinImporter, FrozenImporter, _DefaultPathFinder]
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_ERR_MSG = 'No module named {!r}'
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@ -874,27 +952,9 @@ def _gcd_import(name, package=None, level=0):
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the loader did not.
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"""
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if package:
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if not hasattr(package, 'rindex'):
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raise ValueError("__package__ not set to a string")
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elif package not in sys.modules:
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msg = ("Parent module {0!r} not loaded, cannot perform relative "
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"import")
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raise SystemError(msg.format(package))
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if not name and level == 0:
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raise ValueError("Empty module name")
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_sanity_check(name, package, level)
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if level > 0:
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dot = len(package)
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for x in range(level, 1, -1):
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try:
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dot = package.rindex('.', 0, dot)
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except ValueError:
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raise ValueError("attempted relative import beyond "
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"top-level package")
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if name:
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name = "{0}.{1}".format(package[:dot], name)
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else:
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name = package[:dot]
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name = _resolve_name(name, package, level)
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with _ImportLockContext():
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try:
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module = sys.modules[name]
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@ -905,70 +965,33 @@ def _gcd_import(name, package=None, level=0):
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return module
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except KeyError:
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pass
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parent = name.rpartition('.')[0]
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path = None
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if parent:
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if parent not in sys.modules:
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_gcd_import(parent)
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# Backwards-compatibility; be nicer to skip the dict lookup.
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parent_module = sys.modules[parent]
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try:
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path = parent_module.__path__
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except AttributeError:
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msg = (_ERR_MSG + '; {} is not a package').format(name, parent)
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raise ImportError(msg)
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meta_path = sys.meta_path + _IMPLICIT_META_PATH
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for finder in meta_path:
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loader = finder.find_module(name, path)
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if loader is not None:
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# The parent import may have already imported this module.
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if name not in sys.modules:
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loader.load_module(name)
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break
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else:
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parent, path = _find_search_path(name, _gcd_import)
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loader = _find_module(name, path)
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if loader is None:
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raise ImportError(_ERR_MSG.format(name))
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elif name not in sys.modules:
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# The parent import may have already imported this module.
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loader.load_module(name)
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# Backwards-compatibility; be nicer to skip the dict lookup.
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module = sys.modules[name]
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if parent:
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# Set the module as an attribute on its parent.
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parent_module = sys.modules[parent]
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setattr(parent_module, name.rpartition('.')[2], module)
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# Set __package__ if the loader did not.
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if not hasattr(module, '__package__') or module.__package__ is None:
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# Watch out for what comes out of sys.modules to not be a module,
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# e.g. an int.
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try:
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module.__package__ = module.__name__
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if not hasattr(module, '__path__'):
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module.__package__ = module.__package__.rpartition('.')[0]
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except AttributeError:
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pass
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_set___package__(module)
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return module
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def __import__(name, globals={}, locals={}, fromlist=[], level=0):
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"""Import a module.
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def _return_module(module, name, fromlist, level, import_):
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"""Figure out what __import__ should return.
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The 'globals' argument is used to infer where the import is occuring from
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to handle relative imports. The 'locals' argument is ignored. The
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'fromlist' argument specifies what should exist as attributes on the module
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being imported (e.g. ``from module import <fromlist>``). The 'level'
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argument represents the package location to import from in a relative
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import (e.g. ``from ..pkg import mod`` would have a 'level' of 2).
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The import_ parameter is a callable which takes the name of module to
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import. It is required to decouple the function from assuming importlib's
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import implementation is desired.
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"""
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if not hasattr(name, 'rpartition'):
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raise TypeError("module name must be str, not {}".format(type(name)))
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if level == 0:
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module = _gcd_import(name)
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else:
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# __package__ is not guaranteed to be defined or could be set to None
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# to represent that its proper value is unknown
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package = globals.get('__package__')
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if package is None:
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package = globals['__name__']
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if '__path__' not in globals:
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package = package.rpartition('.')[0]
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module = _gcd_import(name, package, level)
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# The hell that is fromlist ...
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if not fromlist:
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# Return up to the first dot in 'name'. This is complicated by the fact
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@ -989,12 +1012,48 @@ def __import__(name, globals={}, locals={}, fromlist=[], level=0):
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fromlist.extend(module.__all__)
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for x in (y for y in fromlist if not hasattr(module,y)):
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try:
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_gcd_import('{0}.{1}'.format(module.__name__, x))
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import_('{0}.{1}'.format(module.__name__, x))
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except ImportError:
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pass
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return module
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def _calc___package__(globals):
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"""Calculate what __package__ should be.
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__package__ is not guaranteed to be defined or could be set to None
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to represent that its proper value is unknown.
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"""
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package = globals.get('__package__')
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if package is None:
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package = globals['__name__']
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if '__path__' not in globals:
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package = package.rpartition('.')[0]
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return package
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def __import__(name, globals={}, locals={}, fromlist=[], level=0):
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"""Import a module.
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The 'globals' argument is used to infer where the import is occuring from
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to handle relative imports. The 'locals' argument is ignored. The
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'fromlist' argument specifies what should exist as attributes on the module
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being imported (e.g. ``from module import <fromlist>``). The 'level'
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argument represents the package location to import from in a relative
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import (e.g. ``from ..pkg import mod`` would have a 'level' of 2).
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"""
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if not hasattr(name, 'rpartition'):
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raise TypeError("module name must be str, not {}".format(type(name)))
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if level == 0:
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module = _gcd_import(name)
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else:
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package = _calc___package__(globals)
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module = _gcd_import(name, package, level)
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return _return_module(module, name, fromlist, level, _gcd_import)
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def _setup(sys_module, imp_module):
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"""Setup importlib by importing needed built-in modules and injecting them
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into the global namespace.
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