mirror of
https://github.com/python/cpython.git
synced 2026-07-24 02:46:51 -04:00
Brett Cannon
3fe35e6503
implementing in code) the deprecation of imp.reload(). Thanks to Berker Peksag for the patch.
125 lines
4.2 KiB
Python
125 lines
4.2 KiB
Python
"""A pure Python implementation of import."""
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__all__ = ['__import__', 'import_module', 'invalidate_caches', 'reload']
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# Bootstrap help #####################################################
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# Until bootstrapping is complete, DO NOT import any modules that attempt
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# to import importlib._bootstrap (directly or indirectly). Since this
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# partially initialised package would be present in sys.modules, those
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# modules would get an uninitialised copy of the source version, instead
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# of a fully initialised version (either the frozen one or the one
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# initialised below if the frozen one is not available).
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import _imp # Just the builtin component, NOT the full Python module
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import sys
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import types
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try:
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import _frozen_importlib as _bootstrap
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except ModuleNotFoundError:
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from . import _bootstrap
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_bootstrap._setup(sys, _imp)
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else:
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# importlib._bootstrap is the built-in import, ensure we don't create
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# a second copy of the module.
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_bootstrap.__name__ = 'importlib._bootstrap'
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_bootstrap.__package__ = 'importlib'
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_bootstrap.__file__ = __file__.replace('__init__.py', '_bootstrap.py')
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sys.modules['importlib._bootstrap'] = _bootstrap
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# To simplify imports in test code
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_w_long = _bootstrap._w_long
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_r_long = _bootstrap._r_long
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# Fully bootstrapped at this point, import whatever you like, circular
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# dependencies and startup overhead minimisation permitting :)
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# Public API #########################################################
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from ._bootstrap import __import__
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def invalidate_caches():
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"""Call the invalidate_caches() method on all meta path finders stored in
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sys.meta_path (where implemented)."""
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for finder in sys.meta_path:
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if hasattr(finder, 'invalidate_caches'):
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finder.invalidate_caches()
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def find_loader(name, path=None):
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"""Find the loader for the specified module.
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First, sys.modules is checked to see if the module was already imported. If
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so, then sys.modules[name].__loader__ is returned. If that happens to be
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set to None, then ValueError is raised. If the module is not in
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sys.modules, then sys.meta_path is searched for a suitable loader with the
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value of 'path' given to the finders. None is returned if no loader could
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be found.
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Dotted names do not have their parent packages implicitly imported. You will
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most likely need to explicitly import all parent packages in the proper
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order for a submodule to get the correct loader.
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"""
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try:
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loader = sys.modules[name].__loader__
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if loader is None:
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raise ValueError('{}.__loader__ is None'.format(name))
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else:
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return loader
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except KeyError:
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pass
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except AttributeError:
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raise ValueError('{}.__loader__ is not set'.format(name))
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return _bootstrap._find_module(name, path)
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def import_module(name, package=None):
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"""Import a module.
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The 'package' argument is required when performing a relative import. It
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specifies the package to use as the anchor point from which to resolve the
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relative import to an absolute import.
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"""
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level = 0
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if name.startswith('.'):
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if not package:
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raise TypeError("relative imports require the 'package' argument")
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for character in name:
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if character != '.':
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break
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level += 1
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return _bootstrap._gcd_import(name[level:], package, level)
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_RELOADING = {}
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def reload(module):
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"""Reload the module and return it.
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The module must have been successfully imported before.
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"""
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if not module or not isinstance(module, types.ModuleType):
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raise TypeError("reload() argument must be module")
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name = module.__name__
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if name not in sys.modules:
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msg = "module {} not in sys.modules"
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raise ImportError(msg.format(name), name=name)
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if name in _RELOADING:
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return _RELOADING[name]
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_RELOADING[name] = module
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try:
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parent_name = name.rpartition('.')[0]
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if parent_name and parent_name not in sys.modules:
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msg = "parent {!r} not in sys.modules"
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raise ImportError(msg.format(parentname), name=parent_name)
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return module.__loader__.load_module(name)
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finally:
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try:
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del _RELOADING[name]
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except KeyError:
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pass
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