1190 lines
39 KiB
Python
1190 lines
39 KiB
Python
"""Core implementation of import.
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This module is NOT meant to be directly imported! It has been designed such
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that it can be bootstrapped into Python as the implementation of import. As
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such it requires the injection of specific modules and attributes in order to
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work. One should use importlib as the public-facing version of this module.
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"""
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#
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# IMPORTANT: Whenever making changes to this module, be sure to run a top-level
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# `make regen-importlib` followed by `make` in order to get the frozen version
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# of the module updated. Not doing so will result in the Makefile to fail for
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# all others who don't have a ./python around to freeze the module
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# in the early stages of compilation.
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#
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# See importlib._setup() for what is injected into the global namespace.
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# When editing this code be aware that code executed at import time CANNOT
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# reference any injected objects! This includes not only global code but also
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# anything specified at the class level.
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# Bootstrap-related code ######################################################
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_bootstrap_external = None
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def _wrap(new, old):
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"""Simple substitute for functools.update_wrapper."""
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for replace in ['__module__', '__name__', '__qualname__', '__doc__']:
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if hasattr(old, replace):
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setattr(new, replace, getattr(old, replace))
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new.__dict__.update(old.__dict__)
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def _new_module(name):
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return type(sys)(name)
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# Module-level locking ########################################################
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# A dict mapping module names to weakrefs of _ModuleLock instances
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# Dictionary protected by the global import lock
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_module_locks = {}
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# A dict mapping thread ids to _ModuleLock instances
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_blocking_on = {}
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class _DeadlockError(RuntimeError):
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pass
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class _ModuleLock:
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"""A recursive lock implementation which is able to detect deadlocks
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(e.g. thread 1 trying to take locks A then B, and thread 2 trying to
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take locks B then A).
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"""
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def __init__(self, name):
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self.lock = _thread.allocate_lock()
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self.wakeup = _thread.allocate_lock()
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self.name = name
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self.owner = None
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self.count = 0
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self.waiters = 0
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def has_deadlock(self):
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# Deadlock avoidance for concurrent circular imports.
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me = _thread.get_ident()
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tid = self.owner
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seen = set()
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while True:
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lock = _blocking_on.get(tid)
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if lock is None:
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return False
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tid = lock.owner
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if tid == me:
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return True
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if tid in seen:
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# bpo 38091: the chain of tid's we encounter here
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# eventually leads to a fixpoint or a cycle, but
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# does not reach 'me'. This means we would not
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# actually deadlock. This can happen if other
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# threads are at the beginning of acquire() below.
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return False
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seen.add(tid)
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def acquire(self):
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"""
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Acquire the module lock. If a potential deadlock is detected,
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a _DeadlockError is raised.
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Otherwise, the lock is always acquired and True is returned.
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"""
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tid = _thread.get_ident()
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_blocking_on[tid] = self
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try:
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while True:
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with self.lock:
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if self.count == 0 or self.owner == tid:
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self.owner = tid
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self.count += 1
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return True
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if self.has_deadlock():
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raise _DeadlockError('deadlock detected by %r' % self)
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if self.wakeup.acquire(False):
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self.waiters += 1
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# Wait for a release() call
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self.wakeup.acquire()
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self.wakeup.release()
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finally:
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del _blocking_on[tid]
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def release(self):
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tid = _thread.get_ident()
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with self.lock:
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if self.owner != tid:
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raise RuntimeError('cannot release un-acquired lock')
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assert self.count > 0
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self.count -= 1
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if self.count == 0:
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self.owner = None
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if self.waiters:
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self.waiters -= 1
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self.wakeup.release()
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def __repr__(self):
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return '_ModuleLock({!r}) at {}'.format(self.name, id(self))
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class _DummyModuleLock:
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"""A simple _ModuleLock equivalent for Python builds without
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multi-threading support."""
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def __init__(self, name):
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self.name = name
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self.count = 0
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def acquire(self):
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self.count += 1
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return True
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def release(self):
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if self.count == 0:
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raise RuntimeError('cannot release un-acquired lock')
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self.count -= 1
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def __repr__(self):
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return '_DummyModuleLock({!r}) at {}'.format(self.name, id(self))
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class _ModuleLockManager:
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def __init__(self, name):
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self._name = name
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self._lock = None
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def __enter__(self):
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self._lock = _get_module_lock(self._name)
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self._lock.acquire()
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def __exit__(self, *args, **kwargs):
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self._lock.release()
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# The following two functions are for consumption by Python/import.c.
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def _get_module_lock(name):
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"""Get or create the module lock for a given module name.
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Acquire/release internally the global import lock to protect
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_module_locks."""
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_imp.acquire_lock()
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try:
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try:
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lock = _module_locks[name]()
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except KeyError:
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lock = None
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if lock is None:
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if _thread is None:
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lock = _DummyModuleLock(name)
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else:
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lock = _ModuleLock(name)
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def cb(ref, name=name):
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_imp.acquire_lock()
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try:
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# bpo-31070: Check if another thread created a new lock
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# after the previous lock was destroyed
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# but before the weakref callback was called.
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if _module_locks.get(name) is ref:
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del _module_locks[name]
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finally:
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_imp.release_lock()
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_module_locks[name] = _weakref.ref(lock, cb)
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finally:
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_imp.release_lock()
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return lock
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def _lock_unlock_module(name):
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"""Acquires then releases the module lock for a given module name.
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This is used to ensure a module is completely initialized, in the
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event it is being imported by another thread.
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"""
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lock = _get_module_lock(name)
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try:
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lock.acquire()
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except _DeadlockError:
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# Concurrent circular import, we'll accept a partially initialized
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# module object.
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pass
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else:
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lock.release()
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# Frame stripping magic ###############################################
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def _call_with_frames_removed(f, *args, **kwds):
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"""remove_importlib_frames in import.c will always remove sequences
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of importlib frames that end with a call to this function
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Use it instead of a normal call in places where including the importlib
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frames introduces unwanted noise into the traceback (e.g. when executing
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module code)
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"""
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return f(*args, **kwds)
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def _verbose_message(message, *args, verbosity=1):
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"""Print the message to stderr if -v/PYTHONVERBOSE is turned on."""
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if sys.flags.verbose >= verbosity:
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if not message.startswith(('#', 'import ')):
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message = '# ' + message
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print(message.format(*args), file=sys.stderr)
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def _requires_builtin(fxn):
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"""Decorator to verify the named module is built-in."""
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def _requires_builtin_wrapper(self, fullname):
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if fullname not in sys.builtin_module_names:
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raise ImportError('{!r} is not a built-in module'.format(fullname),
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name=fullname)
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return fxn(self, fullname)
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_wrap(_requires_builtin_wrapper, fxn)
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return _requires_builtin_wrapper
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def _requires_frozen(fxn):
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"""Decorator to verify the named module is frozen."""
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def _requires_frozen_wrapper(self, fullname):
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if not _imp.is_frozen(fullname):
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raise ImportError('{!r} is not a frozen module'.format(fullname),
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name=fullname)
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return fxn(self, fullname)
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_wrap(_requires_frozen_wrapper, fxn)
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return _requires_frozen_wrapper
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# Typically used by loader classes as a method replacement.
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def _load_module_shim(self, fullname):
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"""Load the specified module into sys.modules and return it.
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This method is deprecated. Use loader.exec_module instead.
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"""
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spec = spec_from_loader(fullname, self)
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if fullname in sys.modules:
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module = sys.modules[fullname]
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_exec(spec, module)
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return sys.modules[fullname]
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else:
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return _load(spec)
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# Module specifications #######################################################
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def _module_repr(module):
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# The implementation of ModuleType.__repr__().
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loader = getattr(module, '__loader__', None)
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if hasattr(loader, 'module_repr'):
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# As soon as BuiltinImporter, FrozenImporter, and NamespaceLoader
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# drop their implementations for module_repr. we can add a
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# deprecation warning here.
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try:
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return loader.module_repr(module)
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except Exception:
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pass
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try:
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spec = module.__spec__
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except AttributeError:
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pass
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else:
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if spec is not None:
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return _module_repr_from_spec(spec)
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# We could use module.__class__.__name__ instead of 'module' in the
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# various repr permutations.
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try:
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name = module.__name__
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except AttributeError:
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name = '?'
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try:
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filename = module.__file__
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except AttributeError:
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if loader is None:
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return '<module {!r}>'.format(name)
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else:
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return '<module {!r} ({!r})>'.format(name, loader)
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else:
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return '<module {!r} from {!r}>'.format(name, filename)
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class ModuleSpec:
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"""The specification for a module, used for loading.
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A module's spec is the source for information about the module. For
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data associated with the module, including source, use the spec's
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loader.
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`name` is the absolute name of the module. `loader` is the loader
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to use when loading the module. `parent` is the name of the
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package the module is in. The parent is derived from the name.
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`is_package` determines if the module is considered a package or
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not. On modules this is reflected by the `__path__` attribute.
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`origin` is the specific location used by the loader from which to
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load the module, if that information is available. When filename is
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set, origin will match.
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`has_location` indicates that a spec's "origin" reflects a location.
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When this is True, `__file__` attribute of the module is set.
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`cached` is the location of the cached bytecode file, if any. It
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corresponds to the `__cached__` attribute.
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`submodule_search_locations` is the sequence of path entries to
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search when importing submodules. If set, is_package should be
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True--and False otherwise.
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Packages are simply modules that (may) have submodules. If a spec
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has a non-None value in `submodule_search_locations`, the import
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system will consider modules loaded from the spec as packages.
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Only finders (see importlib.abc.MetaPathFinder and
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importlib.abc.PathEntryFinder) should modify ModuleSpec instances.
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"""
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def __init__(self, name, loader, *, origin=None, loader_state=None,
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is_package=None):
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self.name = name
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self.loader = loader
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self.origin = origin
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self.loader_state = loader_state
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self.submodule_search_locations = [] if is_package else None
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# file-location attributes
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self._set_fileattr = False
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self._cached = None
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def __repr__(self):
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args = ['name={!r}'.format(self.name),
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'loader={!r}'.format(self.loader)]
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if self.origin is not None:
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args.append('origin={!r}'.format(self.origin))
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if self.submodule_search_locations is not None:
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args.append('submodule_search_locations={}'
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.format(self.submodule_search_locations))
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return '{}({})'.format(self.__class__.__name__, ', '.join(args))
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def __eq__(self, other):
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smsl = self.submodule_search_locations
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try:
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return (self.name == other.name and
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self.loader == other.loader and
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self.origin == other.origin and
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smsl == other.submodule_search_locations and
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self.cached == other.cached and
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self.has_location == other.has_location)
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except AttributeError:
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return NotImplemented
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@property
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def cached(self):
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if self._cached is None:
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if self.origin is not None and self._set_fileattr:
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if _bootstrap_external is None:
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raise NotImplementedError
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self._cached = _bootstrap_external._get_cached(self.origin)
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return self._cached
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@cached.setter
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def cached(self, cached):
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self._cached = cached
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@property
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def parent(self):
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"""The name of the module's parent."""
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if self.submodule_search_locations is None:
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return self.name.rpartition('.')[0]
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else:
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return self.name
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@property
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def has_location(self):
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return self._set_fileattr
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@has_location.setter
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def has_location(self, value):
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self._set_fileattr = bool(value)
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def spec_from_loader(name, loader, *, origin=None, is_package=None):
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"""Return a module spec based on various loader methods."""
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if hasattr(loader, 'get_filename'):
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if _bootstrap_external is None:
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raise NotImplementedError
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spec_from_file_location = _bootstrap_external.spec_from_file_location
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if is_package is None:
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return spec_from_file_location(name, loader=loader)
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search = [] if is_package else None
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return spec_from_file_location(name, loader=loader,
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submodule_search_locations=search)
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if is_package is None:
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if hasattr(loader, 'is_package'):
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try:
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is_package = loader.is_package(name)
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except ImportError:
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is_package = None # aka, undefined
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else:
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# the default
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is_package = False
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return ModuleSpec(name, loader, origin=origin, is_package=is_package)
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|
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def _spec_from_module(module, loader=None, origin=None):
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# This function is meant for use in _setup().
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try:
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spec = module.__spec__
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except AttributeError:
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pass
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else:
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if spec is not None:
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return spec
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name = module.__name__
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if loader is None:
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try:
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loader = module.__loader__
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except AttributeError:
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# loader will stay None.
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pass
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try:
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location = module.__file__
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except AttributeError:
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location = None
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if origin is None:
|
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if location is None:
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try:
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origin = loader._ORIGIN
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except AttributeError:
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origin = None
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else:
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origin = location
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try:
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cached = module.__cached__
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except AttributeError:
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cached = None
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try:
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submodule_search_locations = list(module.__path__)
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except AttributeError:
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submodule_search_locations = None
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|
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spec = ModuleSpec(name, loader, origin=origin)
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spec._set_fileattr = False if location is None else True
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spec.cached = cached
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spec.submodule_search_locations = submodule_search_locations
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return spec
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|
|
|
|
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def _init_module_attrs(spec, module, *, override=False):
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# The passed-in module may be not support attribute assignment,
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# in which case we simply don't set the attributes.
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# __name__
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if (override or getattr(module, '__name__', None) is None):
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try:
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module.__name__ = spec.name
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except AttributeError:
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pass
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# __loader__
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if override or getattr(module, '__loader__', None) is None:
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loader = spec.loader
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if loader is None:
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|
# A backward compatibility hack.
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|
if spec.submodule_search_locations is not None:
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|
if _bootstrap_external is None:
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raise NotImplementedError
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_NamespaceLoader = _bootstrap_external._NamespaceLoader
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|
|
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loader = _NamespaceLoader.__new__(_NamespaceLoader)
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loader._path = spec.submodule_search_locations
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spec.loader = loader
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|
# While the docs say that module.__file__ is not set for
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|
# built-in modules, and the code below will avoid setting it if
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# spec.has_location is false, this is incorrect for namespace
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|
# packages. Namespace packages have no location, but their
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# __spec__.origin is None, and thus their module.__file__
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|
# should also be None for consistency. While a bit of a hack,
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# this is the best place to ensure this consistency.
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|
#
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|
# See # https://docs.python.org/3/library/importlib.html#importlib.abc.Loader.load_module
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|
# and bpo-32305
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module.__file__ = None
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try:
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module.__loader__ = loader
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except AttributeError:
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|
pass
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# __package__
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|
if override or getattr(module, '__package__', None) is None:
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try:
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module.__package__ = spec.parent
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except AttributeError:
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pass
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# __spec__
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try:
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module.__spec__ = spec
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except AttributeError:
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pass
|
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# __path__
|
|
if override or getattr(module, '__path__', None) is None:
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|
if spec.submodule_search_locations is not None:
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try:
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module.__path__ = spec.submodule_search_locations
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|
except AttributeError:
|
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pass
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# __file__/__cached__
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|
if spec.has_location:
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|
if override or getattr(module, '__file__', None) is None:
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try:
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module.__file__ = spec.origin
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except AttributeError:
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|
pass
|
|
|
|
if override or getattr(module, '__cached__', None) is None:
|
|
if spec.cached is not None:
|
|
try:
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module.__cached__ = spec.cached
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|
except AttributeError:
|
|
pass
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return module
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|
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|
|
def module_from_spec(spec):
|
|
"""Create a module based on the provided spec."""
|
|
# Typically loaders will not implement create_module().
|
|
module = None
|
|
if hasattr(spec.loader, 'create_module'):
|
|
# If create_module() returns `None` then it means default
|
|
# module creation should be used.
|
|
module = spec.loader.create_module(spec)
|
|
elif hasattr(spec.loader, 'exec_module'):
|
|
raise ImportError('loaders that define exec_module() '
|
|
'must also define create_module()')
|
|
if module is None:
|
|
module = _new_module(spec.name)
|
|
_init_module_attrs(spec, module)
|
|
return module
|
|
|
|
|
|
def _module_repr_from_spec(spec):
|
|
"""Return the repr to use for the module."""
|
|
# We mostly replicate _module_repr() using the spec attributes.
|
|
name = '?' if spec.name is None else spec.name
|
|
if spec.origin is None:
|
|
if spec.loader is None:
|
|
return '<module {!r}>'.format(name)
|
|
else:
|
|
return '<module {!r} ({!r})>'.format(name, spec.loader)
|
|
else:
|
|
if spec.has_location:
|
|
return '<module {!r} from {!r}>'.format(name, spec.origin)
|
|
else:
|
|
return '<module {!r} ({})>'.format(spec.name, spec.origin)
|
|
|
|
|
|
# Used by importlib.reload() and _load_module_shim().
|
|
def _exec(spec, module):
|
|
"""Execute the spec's specified module in an existing module's namespace."""
|
|
name = spec.name
|
|
with _ModuleLockManager(name):
|
|
if sys.modules.get(name) is not module:
|
|
msg = 'module {!r} not in sys.modules'.format(name)
|
|
raise ImportError(msg, name=name)
|
|
try:
|
|
if spec.loader is None:
|
|
if spec.submodule_search_locations is None:
|
|
raise ImportError('missing loader', name=spec.name)
|
|
# Namespace package.
|
|
_init_module_attrs(spec, module, override=True)
|
|
else:
|
|
_init_module_attrs(spec, module, override=True)
|
|
if not hasattr(spec.loader, 'exec_module'):
|
|
# (issue19713) Once BuiltinImporter and ExtensionFileLoader
|
|
# have exec_module() implemented, we can add a deprecation
|
|
# warning here.
|
|
spec.loader.load_module(name)
|
|
else:
|
|
spec.loader.exec_module(module)
|
|
finally:
|
|
# Update the order of insertion into sys.modules for module
|
|
# clean-up at shutdown.
|
|
module = sys.modules.pop(spec.name)
|
|
sys.modules[spec.name] = module
|
|
return module
|
|
|
|
|
|
def _load_backward_compatible(spec):
|
|
# (issue19713) Once BuiltinImporter and ExtensionFileLoader
|
|
# have exec_module() implemented, we can add a deprecation
|
|
# warning here.
|
|
try:
|
|
spec.loader.load_module(spec.name)
|
|
except:
|
|
if spec.name in sys.modules:
|
|
module = sys.modules.pop(spec.name)
|
|
sys.modules[spec.name] = module
|
|
raise
|
|
# The module must be in sys.modules at this point!
|
|
# Move it to the end of sys.modules.
|
|
module = sys.modules.pop(spec.name)
|
|
sys.modules[spec.name] = module
|
|
if getattr(module, '__loader__', None) is None:
|
|
try:
|
|
module.__loader__ = spec.loader
|
|
except AttributeError:
|
|
pass
|
|
if getattr(module, '__package__', None) is None:
|
|
try:
|
|
# Since module.__path__ may not line up with
|
|
# spec.submodule_search_paths, we can't necessarily rely
|
|
# on spec.parent here.
|
|
module.__package__ = module.__name__
|
|
if not hasattr(module, '__path__'):
|
|
module.__package__ = spec.name.rpartition('.')[0]
|
|
except AttributeError:
|
|
pass
|
|
if getattr(module, '__spec__', None) is None:
|
|
try:
|
|
module.__spec__ = spec
|
|
except AttributeError:
|
|
pass
|
|
return module
|
|
|
|
def _load_unlocked(spec):
|
|
# A helper for direct use by the import system.
|
|
if spec.loader is not None:
|
|
# Not a namespace package.
|
|
if not hasattr(spec.loader, 'exec_module'):
|
|
return _load_backward_compatible(spec)
|
|
|
|
module = module_from_spec(spec)
|
|
|
|
# This must be done before putting the module in sys.modules
|
|
# (otherwise an optimization shortcut in import.c becomes
|
|
# wrong).
|
|
spec._initializing = True
|
|
try:
|
|
sys.modules[spec.name] = module
|
|
try:
|
|
if spec.loader is None:
|
|
if spec.submodule_search_locations is None:
|
|
raise ImportError('missing loader', name=spec.name)
|
|
# A namespace package so do nothing.
|
|
else:
|
|
spec.loader.exec_module(module)
|
|
except:
|
|
try:
|
|
del sys.modules[spec.name]
|
|
except KeyError:
|
|
pass
|
|
raise
|
|
# Move the module to the end of sys.modules.
|
|
# We don't ensure that the import-related module attributes get
|
|
# set in the sys.modules replacement case. Such modules are on
|
|
# their own.
|
|
module = sys.modules.pop(spec.name)
|
|
sys.modules[spec.name] = module
|
|
_verbose_message('import {!r} # {!r}', spec.name, spec.loader)
|
|
finally:
|
|
spec._initializing = False
|
|
|
|
return module
|
|
|
|
# A method used during testing of _load_unlocked() and by
|
|
# _load_module_shim().
|
|
def _load(spec):
|
|
"""Return a new module object, loaded by the spec's loader.
|
|
|
|
The module is not added to its parent.
|
|
|
|
If a module is already in sys.modules, that existing module gets
|
|
clobbered.
|
|
|
|
"""
|
|
with _ModuleLockManager(spec.name):
|
|
return _load_unlocked(spec)
|
|
|
|
|
|
# Loaders #####################################################################
|
|
|
|
class BuiltinImporter:
|
|
|
|
"""Meta path import for built-in modules.
|
|
|
|
All methods are either class or static methods to avoid the need to
|
|
instantiate the class.
|
|
|
|
"""
|
|
|
|
_ORIGIN = "built-in"
|
|
|
|
@staticmethod
|
|
def module_repr(module):
|
|
"""Return repr for the module.
|
|
|
|
The method is deprecated. The import machinery does the job itself.
|
|
|
|
"""
|
|
return f'<module {module.__name__!r} ({BuiltinImporter._ORIGIN})>'
|
|
|
|
@classmethod
|
|
def find_spec(cls, fullname, path=None, target=None):
|
|
if path is not None:
|
|
return None
|
|
if _imp.is_builtin(fullname):
|
|
return spec_from_loader(fullname, cls, origin=cls._ORIGIN)
|
|
else:
|
|
return None
|
|
|
|
@classmethod
|
|
def find_module(cls, fullname, path=None):
|
|
"""Find the built-in module.
|
|
|
|
If 'path' is ever specified then the search is considered a failure.
|
|
|
|
This method is deprecated. Use find_spec() instead.
|
|
|
|
"""
|
|
spec = cls.find_spec(fullname, path)
|
|
return spec.loader if spec is not None else None
|
|
|
|
@classmethod
|
|
def create_module(self, spec):
|
|
"""Create a built-in module"""
|
|
if spec.name not in sys.builtin_module_names:
|
|
raise ImportError('{!r} is not a built-in module'.format(spec.name),
|
|
name=spec.name)
|
|
return _call_with_frames_removed(_imp.create_builtin, spec)
|
|
|
|
@classmethod
|
|
def exec_module(self, module):
|
|
"""Exec a built-in module"""
|
|
_call_with_frames_removed(_imp.exec_builtin, module)
|
|
|
|
@classmethod
|
|
@_requires_builtin
|
|
def get_code(cls, fullname):
|
|
"""Return None as built-in modules do not have code objects."""
|
|
return None
|
|
|
|
@classmethod
|
|
@_requires_builtin
|
|
def get_source(cls, fullname):
|
|
"""Return None as built-in modules do not have source code."""
|
|
return None
|
|
|
|
@classmethod
|
|
@_requires_builtin
|
|
def is_package(cls, fullname):
|
|
"""Return False as built-in modules are never packages."""
|
|
return False
|
|
|
|
load_module = classmethod(_load_module_shim)
|
|
|
|
|
|
class FrozenImporter:
|
|
|
|
"""Meta path import for frozen modules.
|
|
|
|
All methods are either class or static methods to avoid the need to
|
|
instantiate the class.
|
|
|
|
"""
|
|
|
|
_ORIGIN = "frozen"
|
|
|
|
@staticmethod
|
|
def module_repr(m):
|
|
"""Return repr for the module.
|
|
|
|
The method is deprecated. The import machinery does the job itself.
|
|
|
|
"""
|
|
return '<module {!r} ({})>'.format(m.__name__, FrozenImporter._ORIGIN)
|
|
|
|
@classmethod
|
|
def find_spec(cls, fullname, path=None, target=None):
|
|
if _imp.is_frozen(fullname):
|
|
return spec_from_loader(fullname, cls, origin=cls._ORIGIN)
|
|
else:
|
|
return None
|
|
|
|
@classmethod
|
|
def find_module(cls, fullname, path=None):
|
|
"""Find a frozen module.
|
|
|
|
This method is deprecated. Use find_spec() instead.
|
|
|
|
"""
|
|
return cls if _imp.is_frozen(fullname) else None
|
|
|
|
@classmethod
|
|
def create_module(cls, spec):
|
|
"""Use default semantics for module creation."""
|
|
|
|
@staticmethod
|
|
def exec_module(module):
|
|
name = module.__spec__.name
|
|
if not _imp.is_frozen(name):
|
|
raise ImportError('{!r} is not a frozen module'.format(name),
|
|
name=name)
|
|
code = _call_with_frames_removed(_imp.get_frozen_object, name)
|
|
exec(code, module.__dict__)
|
|
|
|
@classmethod
|
|
def load_module(cls, fullname):
|
|
"""Load a frozen module.
|
|
|
|
This method is deprecated. Use exec_module() instead.
|
|
|
|
"""
|
|
return _load_module_shim(cls, fullname)
|
|
|
|
@classmethod
|
|
@_requires_frozen
|
|
def get_code(cls, fullname):
|
|
"""Return the code object for the frozen module."""
|
|
return _imp.get_frozen_object(fullname)
|
|
|
|
@classmethod
|
|
@_requires_frozen
|
|
def get_source(cls, fullname):
|
|
"""Return None as frozen modules do not have source code."""
|
|
return None
|
|
|
|
@classmethod
|
|
@_requires_frozen
|
|
def is_package(cls, fullname):
|
|
"""Return True if the frozen module is a package."""
|
|
return _imp.is_frozen_package(fullname)
|
|
|
|
|
|
# Import itself ###############################################################
|
|
|
|
class _ImportLockContext:
|
|
|
|
"""Context manager for the import lock."""
|
|
|
|
def __enter__(self):
|
|
"""Acquire the import lock."""
|
|
_imp.acquire_lock()
|
|
|
|
def __exit__(self, exc_type, exc_value, exc_traceback):
|
|
"""Release the import lock regardless of any raised exceptions."""
|
|
_imp.release_lock()
|
|
|
|
|
|
def _resolve_name(name, package, level):
|
|
"""Resolve a relative module name to an absolute one."""
|
|
bits = package.rsplit('.', level - 1)
|
|
if len(bits) < level:
|
|
raise ImportError('attempted relative import beyond top-level package')
|
|
base = bits[0]
|
|
return '{}.{}'.format(base, name) if name else base
|
|
|
|
|
|
def _find_spec_legacy(finder, name, path):
|
|
# This would be a good place for a DeprecationWarning if
|
|
# we ended up going that route.
|
|
loader = finder.find_module(name, path)
|
|
if loader is None:
|
|
return None
|
|
return spec_from_loader(name, loader)
|
|
|
|
|
|
def _find_spec(name, path, target=None):
|
|
"""Find a module's spec."""
|
|
meta_path = sys.meta_path
|
|
if meta_path is None:
|
|
# PyImport_Cleanup() is running or has been called.
|
|
raise ImportError("sys.meta_path is None, Python is likely "
|
|
"shutting down")
|
|
|
|
if not meta_path:
|
|
_warnings.warn('sys.meta_path is empty', ImportWarning)
|
|
|
|
# We check sys.modules here for the reload case. While a passed-in
|
|
# target will usually indicate a reload there is no guarantee, whereas
|
|
# sys.modules provides one.
|
|
is_reload = name in sys.modules
|
|
for finder in meta_path:
|
|
with _ImportLockContext():
|
|
try:
|
|
find_spec = finder.find_spec
|
|
except AttributeError:
|
|
spec = _find_spec_legacy(finder, name, path)
|
|
if spec is None:
|
|
continue
|
|
else:
|
|
spec = find_spec(name, path, target)
|
|
if spec is not None:
|
|
# The parent import may have already imported this module.
|
|
if not is_reload and name in sys.modules:
|
|
module = sys.modules[name]
|
|
try:
|
|
__spec__ = module.__spec__
|
|
except AttributeError:
|
|
# We use the found spec since that is the one that
|
|
# we would have used if the parent module hadn't
|
|
# beaten us to the punch.
|
|
return spec
|
|
else:
|
|
if __spec__ is None:
|
|
return spec
|
|
else:
|
|
return __spec__
|
|
else:
|
|
return spec
|
|
else:
|
|
return None
|
|
|
|
|
|
def _sanity_check(name, package, level):
|
|
"""Verify arguments are "sane"."""
|
|
if not isinstance(name, str):
|
|
raise TypeError('module name must be str, not {}'.format(type(name)))
|
|
if level < 0:
|
|
raise ValueError('level must be >= 0')
|
|
if level > 0:
|
|
if not isinstance(package, str):
|
|
raise TypeError('__package__ not set to a string')
|
|
elif not package:
|
|
raise ImportError('attempted relative import with no known parent '
|
|
'package')
|
|
if not name and level == 0:
|
|
raise ValueError('Empty module name')
|
|
|
|
|
|
_ERR_MSG_PREFIX = 'No module named '
|
|
_ERR_MSG = _ERR_MSG_PREFIX + '{!r}'
|
|
|
|
def _find_and_load_unlocked(name, import_):
|
|
path = None
|
|
parent = name.rpartition('.')[0]
|
|
if parent:
|
|
if parent not in sys.modules:
|
|
_call_with_frames_removed(import_, parent)
|
|
# Crazy side-effects!
|
|
if name in sys.modules:
|
|
return sys.modules[name]
|
|
parent_module = sys.modules[parent]
|
|
try:
|
|
path = parent_module.__path__
|
|
except AttributeError:
|
|
msg = (_ERR_MSG + '; {!r} is not a package').format(name, parent)
|
|
raise ModuleNotFoundError(msg, name=name) from None
|
|
spec = _find_spec(name, path)
|
|
if spec is None:
|
|
raise ModuleNotFoundError(_ERR_MSG.format(name), name=name)
|
|
else:
|
|
module = _load_unlocked(spec)
|
|
if parent:
|
|
# Set the module as an attribute on its parent.
|
|
parent_module = sys.modules[parent]
|
|
child = name.rpartition('.')[2]
|
|
try:
|
|
setattr(parent_module, child, module)
|
|
except AttributeError:
|
|
msg = f"Cannot set an attribute on {parent!r} for child module {child!r}"
|
|
_warnings.warn(msg, ImportWarning)
|
|
return module
|
|
|
|
|
|
_NEEDS_LOADING = object()
|
|
|
|
|
|
def _find_and_load(name, import_):
|
|
"""Find and load the module."""
|
|
with _ModuleLockManager(name):
|
|
module = sys.modules.get(name, _NEEDS_LOADING)
|
|
if module is _NEEDS_LOADING:
|
|
return _find_and_load_unlocked(name, import_)
|
|
|
|
if module is None:
|
|
message = ('import of {} halted; '
|
|
'None in sys.modules'.format(name))
|
|
raise ModuleNotFoundError(message, name=name)
|
|
|
|
_lock_unlock_module(name)
|
|
return module
|
|
|
|
|
|
def _gcd_import(name, package=None, level=0):
|
|
"""Import and return the module based on its name, the package the call is
|
|
being made from, and the level adjustment.
|
|
|
|
This function represents the greatest common denominator of functionality
|
|
between import_module and __import__. This includes setting __package__ if
|
|
the loader did not.
|
|
|
|
"""
|
|
_sanity_check(name, package, level)
|
|
if level > 0:
|
|
name = _resolve_name(name, package, level)
|
|
return _find_and_load(name, _gcd_import)
|
|
|
|
|
|
def _handle_fromlist(module, fromlist, import_, *, recursive=False):
|
|
"""Figure out what __import__ should return.
|
|
|
|
The import_ parameter is a callable which takes the name of module to
|
|
import. It is required to decouple the function from assuming importlib's
|
|
import implementation is desired.
|
|
|
|
"""
|
|
# The hell that is fromlist ...
|
|
# If a package was imported, try to import stuff from fromlist.
|
|
for x in fromlist:
|
|
if not isinstance(x, str):
|
|
if recursive:
|
|
where = module.__name__ + '.__all__'
|
|
else:
|
|
where = "``from list''"
|
|
raise TypeError(f"Item in {where} must be str, "
|
|
f"not {type(x).__name__}")
|
|
elif x == '*':
|
|
if not recursive and hasattr(module, '__all__'):
|
|
_handle_fromlist(module, module.__all__, import_,
|
|
recursive=True)
|
|
elif not hasattr(module, x):
|
|
from_name = '{}.{}'.format(module.__name__, x)
|
|
try:
|
|
_call_with_frames_removed(import_, from_name)
|
|
except ModuleNotFoundError as exc:
|
|
# Backwards-compatibility dictates we ignore failed
|
|
# imports triggered by fromlist for modules that don't
|
|
# exist.
|
|
if (exc.name == from_name and
|
|
sys.modules.get(from_name, _NEEDS_LOADING) is not None):
|
|
continue
|
|
raise
|
|
return module
|
|
|
|
|
|
def _calc___package__(globals):
|
|
"""Calculate what __package__ should be.
|
|
|
|
__package__ is not guaranteed to be defined or could be set to None
|
|
to represent that its proper value is unknown.
|
|
|
|
"""
|
|
package = globals.get('__package__')
|
|
spec = globals.get('__spec__')
|
|
if package is not None:
|
|
if spec is not None and package != spec.parent:
|
|
_warnings.warn("__package__ != __spec__.parent "
|
|
f"({package!r} != {spec.parent!r})",
|
|
ImportWarning, stacklevel=3)
|
|
return package
|
|
elif spec is not None:
|
|
return spec.parent
|
|
else:
|
|
_warnings.warn("can't resolve package from __spec__ or __package__, "
|
|
"falling back on __name__ and __path__",
|
|
ImportWarning, stacklevel=3)
|
|
package = globals['__name__']
|
|
if '__path__' not in globals:
|
|
package = package.rpartition('.')[0]
|
|
return package
|
|
|
|
|
|
def __import__(name, globals=None, locals=None, fromlist=(), level=0):
|
|
"""Import a module.
|
|
|
|
The 'globals' argument is used to infer where the import is occurring from
|
|
to handle relative imports. The 'locals' argument is ignored. The
|
|
'fromlist' argument specifies what should exist as attributes on the module
|
|
being imported (e.g. ``from module import <fromlist>``). The 'level'
|
|
argument represents the package location to import from in a relative
|
|
import (e.g. ``from ..pkg import mod`` would have a 'level' of 2).
|
|
|
|
"""
|
|
if level == 0:
|
|
module = _gcd_import(name)
|
|
else:
|
|
globals_ = globals if globals is not None else {}
|
|
package = _calc___package__(globals_)
|
|
module = _gcd_import(name, package, level)
|
|
if not fromlist:
|
|
# Return up to the first dot in 'name'. This is complicated by the fact
|
|
# that 'name' may be relative.
|
|
if level == 0:
|
|
return _gcd_import(name.partition('.')[0])
|
|
elif not name:
|
|
return module
|
|
else:
|
|
# Figure out where to slice the module's name up to the first dot
|
|
# in 'name'.
|
|
cut_off = len(name) - len(name.partition('.')[0])
|
|
# Slice end needs to be positive to alleviate need to special-case
|
|
# when ``'.' not in name``.
|
|
return sys.modules[module.__name__[:len(module.__name__)-cut_off]]
|
|
elif hasattr(module, '__path__'):
|
|
return _handle_fromlist(module, fromlist, _gcd_import)
|
|
else:
|
|
return module
|
|
|
|
|
|
def _builtin_from_name(name):
|
|
spec = BuiltinImporter.find_spec(name)
|
|
if spec is None:
|
|
raise ImportError('no built-in module named ' + name)
|
|
return _load_unlocked(spec)
|
|
|
|
|
|
def _setup(sys_module, _imp_module):
|
|
"""Setup importlib by importing needed built-in modules and injecting them
|
|
into the global namespace.
|
|
|
|
As sys is needed for sys.modules access and _imp is needed to load built-in
|
|
modules, those two modules must be explicitly passed in.
|
|
|
|
"""
|
|
global _imp, sys
|
|
_imp = _imp_module
|
|
sys = sys_module
|
|
|
|
# Set up the spec for existing builtin/frozen modules.
|
|
module_type = type(sys)
|
|
for name, module in sys.modules.items():
|
|
if isinstance(module, module_type):
|
|
if name in sys.builtin_module_names:
|
|
loader = BuiltinImporter
|
|
elif _imp.is_frozen(name):
|
|
loader = FrozenImporter
|
|
else:
|
|
continue
|
|
spec = _spec_from_module(module, loader)
|
|
_init_module_attrs(spec, module)
|
|
|
|
# Directly load built-in modules needed during bootstrap.
|
|
self_module = sys.modules[__name__]
|
|
for builtin_name in ('_thread', '_warnings', '_weakref'):
|
|
if builtin_name not in sys.modules:
|
|
builtin_module = _builtin_from_name(builtin_name)
|
|
else:
|
|
builtin_module = sys.modules[builtin_name]
|
|
setattr(self_module, builtin_name, builtin_module)
|
|
|
|
|
|
def _install(sys_module, _imp_module):
|
|
"""Install importers for builtin and frozen modules"""
|
|
_setup(sys_module, _imp_module)
|
|
|
|
sys.meta_path.append(BuiltinImporter)
|
|
sys.meta_path.append(FrozenImporter)
|
|
|
|
|
|
def _install_external_importers():
|
|
"""Install importers that require external filesystem access"""
|
|
global _bootstrap_external
|
|
import _frozen_importlib_external
|
|
_bootstrap_external = _frozen_importlib_external
|
|
_frozen_importlib_external._install(sys.modules[__name__])
|