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61b14251d3
This required moving the class from importlib/abc.py into importlib/_bootstrap.py and jiggering some code to work better with the class. This included changing how the file finder worked to better meet import semantics. This also led to fixing importlib to handle the empty string from sys.path as import currently does (and making me wish we didn't support that instead just required people to insert '.' instead to represent cwd). It also required making the new set_data abstractmethod create any needed subdirectories implicitly thanks to __pycache__ (it was either this or grow the SourceLoader ABC to gain an 'exists' method and either a mkdir method or have set_data with no data arg mean to create a directory). Lastly, as an optimization the file loaders cache the file path where the finder found something to use for loading (this is thanks to having a sourceless loader separate from the source loader to simplify the code and cut out stat calls). Unfortunately test_runpy assumed a loader would always work for a module, even if you changed from underneath it what it was expected to work with. By simply dropping the previous loader in test_runpy so the proper loader can be returned by the finder fixed the failure. At this point importlib deviates from import on two points: 1. The exception raised when trying to import a file is different (import does an explicit file check to print a special message, importlib just says the path cannot be imported as if it was just some module name). 2. the co_filename on a code object is not being set to where bytecode was actually loaded from instead of where the marshalled code object originally came from (a solution for this has already been agreed upon on python-dev but has not been implemented yet; issue8611).
284 lines
9.9 KiB
Python
284 lines
9.9 KiB
Python
"""Abstract base classes related to import."""
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from . import _bootstrap
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from . import machinery
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from . import util
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import abc
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import imp
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import io
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import marshal
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import os.path
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import sys
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import tokenize
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import types
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import warnings
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class Loader(metaclass=abc.ABCMeta):
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"""Abstract base class for import loaders."""
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@abc.abstractmethod
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def load_module(self, fullname:str) -> types.ModuleType:
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"""Abstract method which when implemented should load a module."""
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raise NotImplementedError
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class Finder(metaclass=abc.ABCMeta):
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"""Abstract base class for import finders."""
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@abc.abstractmethod
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def find_module(self, fullname:str, path:[str]=None) -> Loader:
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"""Abstract method which when implemented should find a module."""
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raise NotImplementedError
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Finder.register(machinery.BuiltinImporter)
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Finder.register(machinery.FrozenImporter)
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Finder.register(machinery.PathFinder)
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class ResourceLoader(Loader):
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"""Abstract base class for loaders which can return data from their
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back-end storage.
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This ABC represents one of the optional protocols specified by PEP 302.
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"""
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@abc.abstractmethod
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def get_data(self, path:str) -> bytes:
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"""Abstract method which when implemented should return the bytes for
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the specified path."""
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raise NotImplementedError
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class InspectLoader(Loader):
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"""Abstract base class for loaders which support inspection about the
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modules they can load.
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This ABC represents one of the optional protocols specified by PEP 302.
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"""
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@abc.abstractmethod
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def is_package(self, fullname:str) -> bool:
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"""Abstract method which when implemented should return whether the
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module is a package."""
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raise NotImplementedError
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@abc.abstractmethod
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def get_code(self, fullname:str) -> types.CodeType:
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"""Abstract method which when implemented should return the code object
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for the module"""
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raise NotImplementedError
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@abc.abstractmethod
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def get_source(self, fullname:str) -> str:
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"""Abstract method which should return the source code for the
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module."""
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raise NotImplementedError
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InspectLoader.register(machinery.BuiltinImporter)
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InspectLoader.register(machinery.FrozenImporter)
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class ExecutionLoader(InspectLoader):
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"""Abstract base class for loaders that wish to support the execution of
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modules as scripts.
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This ABC represents one of the optional protocols specified in PEP 302.
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"""
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@abc.abstractmethod
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def get_filename(self, fullname:str) -> str:
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"""Abstract method which should return the value that __file__ is to be
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set to."""
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raise NotImplementedError
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class SourceLoader(_bootstrap.SourceLoader, ResourceLoader, ExecutionLoader):
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"""Abstract base class for loading source code (and optionally any
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corresponding bytecode).
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To support loading from source code, the abstractmethods inherited from
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ResourceLoader and ExecutionLoader need to be implemented. To also support
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loading from bytecode, the optional methods specified directly by this ABC
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is required.
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Inherited abstractmethods not implemented in this ABC:
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* ResourceLoader.get_data
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* ExecutionLoader.get_filename
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"""
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class PyLoader(SourceLoader):
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"""Implement the deprecated PyLoader ABC in terms of SourceLoader.
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This class has been deprecated! It is slated for removal in Python 3.4.
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If compatibility with Python 3.1 is not needed then implement the
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SourceLoader ABC instead of this class. If Python 3.1 compatibility is
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needed, then use the following idiom to have a single class that is
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compatible with Python 3.1 onwards::
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try:
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from importlib.abc import SourceLoader
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except ImportError:
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from importlib.abc import PyLoader as SourceLoader
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class CustomLoader(SourceLoader):
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def get_filename(self, fullname):
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# Implement ...
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def source_path(self, fullname):
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'''Implement source_path in terms of get_filename.'''
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try:
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return self.get_filename(fullname)
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except ImportError:
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return None
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def is_package(self, fullname):
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filename = os.path.basename(self.get_filename(fullname))
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return os.path.splitext(filename)[0] == '__init__'
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"""
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@abc.abstractmethod
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def is_package(self, fullname):
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raise NotImplementedError
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@abc.abstractmethod
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def source_path(self, fullname:str) -> object:
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"""Abstract method which when implemented should return the path to the
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source code for the module."""
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raise NotImplementedError
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def get_filename(self, fullname):
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"""Implement get_filename in terms of source_path.
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As get_filename should only return a source file path there is no
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chance of the path not existing but loading still being possible, so
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ImportError should propagate instead of being turned into returning
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None.
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"""
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warnings.warn("importlib.abc.PyLoader is deprecated and is "
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"slated for removal in Python 3.4; "
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"use SourceLoader instead. "
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"See the importlib documentation on how to be "
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"compatible with Python 3.1 onwards.",
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PendingDeprecationWarning)
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path = self.source_path(fullname)
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if path is None:
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raise ImportError
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else:
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return path
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class PyPycLoader(PyLoader):
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"""Abstract base class to assist in loading source and bytecode by
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requiring only back-end storage methods to be implemented.
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This class has been deprecated! Removal is slated for Python 3.4. Implement
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the SourceLoader ABC instead. If Python 3.1 compatibility is needed, see
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PyLoader.
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The methods get_code, get_source, and load_module are implemented for the
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user.
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"""
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def get_filename(self, fullname):
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"""Return the source or bytecode file path."""
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path = self.source_path(fullname)
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if path is not None:
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return path
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path = self.bytecode_path(fullname)
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if path is not None:
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return path
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raise ImportError("no source or bytecode path available for "
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"{0!r}".format(fullname))
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def get_code(self, fullname):
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"""Get a code object from source or bytecode."""
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warnings.warn("importlib.abc.PyPycLoader is deprecated and slated for "
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"removal in Python 3.4; use SourceLoader instead. "
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"If Python 3.1 compatibility is required, see the "
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"latest documentation for PyLoader.",
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PendingDeprecationWarning)
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source_timestamp = self.source_mtime(fullname)
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# Try to use bytecode if it is available.
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bytecode_path = self.bytecode_path(fullname)
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if bytecode_path:
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data = self.get_data(bytecode_path)
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try:
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magic = data[:4]
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if len(magic) < 4:
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raise ImportError("bad magic number in {}".format(fullname))
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raw_timestamp = data[4:8]
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if len(raw_timestamp) < 4:
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raise EOFError("bad timestamp in {}".format(fullname))
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pyc_timestamp = marshal._r_long(raw_timestamp)
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bytecode = data[8:]
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# Verify that the magic number is valid.
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if imp.get_magic() != magic:
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raise ImportError("bad magic number in {}".format(fullname))
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# Verify that the bytecode is not stale (only matters when
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# there is source to fall back on.
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if source_timestamp:
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if pyc_timestamp < source_timestamp:
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raise ImportError("bytecode is stale")
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except (ImportError, EOFError):
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# If source is available give it a shot.
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if source_timestamp is not None:
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pass
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else:
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raise
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else:
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# Bytecode seems fine, so try to use it.
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return marshal.loads(bytecode)
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elif source_timestamp is None:
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raise ImportError("no source or bytecode available to create code "
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"object for {0!r}".format(fullname))
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# Use the source.
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source_path = self.source_path(fullname)
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if source_path is None:
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message = "a source path must exist to load {0}".format(fullname)
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raise ImportError(message)
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source = self.get_data(source_path)
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code_object = compile(source, source_path, 'exec', dont_inherit=True)
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# Generate bytecode and write it out.
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if not sys.dont_write_bytecode:
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data = bytearray(imp.get_magic())
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data.extend(marshal._w_long(source_timestamp))
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data.extend(marshal.dumps(code_object))
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self.write_bytecode(fullname, data)
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return code_object
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@abc.abstractmethod
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def source_mtime(self, fullname:str) -> int:
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"""Abstract method which when implemented should return the
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modification time for the source of the module."""
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raise NotImplementedError
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@abc.abstractmethod
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def bytecode_path(self, fullname:str) -> object:
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"""Abstract method which when implemented should return the path to the
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bytecode for the module."""
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raise NotImplementedError
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@abc.abstractmethod
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def write_bytecode(self, fullname:str, bytecode:bytes) -> bool:
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"""Abstract method which when implemented should attempt to write the
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bytecode for the module, returning a boolean representing whether the
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bytecode was written or not."""
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raise NotImplementedError
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