[PEP 451] Updates in response to the latest feedback.
This includes removing the remaining ModuleSpec methods and de-emphasizing that find_spec() returns actual ModuleSpec instances.
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Eric Snow
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69
pep-0451.txt
69
pep-0451.txt
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@ -240,8 +240,8 @@ detail is available in later sections.
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importlib.machinery.ModuleSpec (new)
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------------------------------------
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A specification for a module's import-system-related state. See the
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`ModuleSpec`_ section below for a more detailed description.
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An encapsulation of a module's import-system-related state during import.
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See the `ModuleSpec`_ section below for a more detailed description.
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* ModuleSpec(name, loader, \*, origin=None, loader_state=None, is_package=None)
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@ -263,13 +263,6 @@ Attributes:
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* has_location (RO-property) - a flag indicating whether or not the
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module's "origin" attribute refers to a location.
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Instance Methods:
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* module_repr() - provide a repr string for the spec'ed module;
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non-locatable modules will use their origin (e.g. "built-in").
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* init_module_attrs(module) - set any of a module's import-related
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attributes that aren't already set.
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importlib.util Additions
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------------------------
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@ -289,6 +282,12 @@ Other API Additions
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importlib.find_loader() (which it replaces), but return a spec instead
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of a loader.
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For finders:
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* importlib.abc.MetaPathFinder.find_spec(name, path) and
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importlib.abc.PathEntryFinder.find_spec(name) will return a module
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spec to use during import.
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For loaders:
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* importlib.abc.Loader.exec_module(module) will execute a module in its
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@ -443,34 +442,30 @@ factory functions nor any the instance methods.
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How Loading Will Work
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=====================
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Here is an outline of what ModuleSpec does during loading::
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def load(self):
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if not hasattr(self.loader, 'exec_module'):
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module = self.loader.load_module(self.name)
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self.init_module_attrs(module)
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return sys.modules[self.name]
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Here is an outline of what the import machinery does during loading,
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adjusted to take advantage of the module's spec and the new loader API::
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module = None
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if hasattr(self.loader, 'create_module'):
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module = self.loader.create_module(self)
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if hasattr(spec.loader, 'create_module'):
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module = spec.loader.create_module(spec)
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if module is None:
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module = ModuleType(self.name)
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self.init_module_attrs(module)
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module = ModuleType(spec.name)
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# The import-related module attributes get set here:
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_init_module_attrs(module)
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sys.modules[self.name] = module
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if not hasattr(spec.loader, 'exec_module'):
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module = spec.loader.load_module(spec.name)
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else:
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sys.modules[spec.name] = module
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try:
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self.loader.exec_module(module)
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spec.loader.exec_module(module)
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except BaseException:
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try:
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del sys.modules[self.name]
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del sys.modules[spec.name]
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except KeyError:
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pass
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raise
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return sys.modules[self.name]
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Note: no "load" method is actually implemented as part of the public
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ModuleSpec API.
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module_to_return = sys.modules[spec.name]
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These steps are exactly what Loader.load_module() is already
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expected to do. Loaders will thus be simplified since they will only
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@ -494,8 +489,8 @@ Each of the following names is an attribute on ModuleSpec objects. A
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value of None indicates "not set". This contrasts with module
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objects where the attribute simply doesn't exist. Most of the
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attributes correspond to the import-related attributes of modules. Here
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is the mapping. The reverse of this mapping is used by
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ModuleSpec.init_module_attrs().
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is the mapping. The reverse of this mapping describes how the import
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machinery sets the module attributes right before calling exec_module().
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========================== ==============
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On ModuleSpec On Modules
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@ -523,7 +518,7 @@ involve changing the state of a module's spec.
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"origin" is a string for the name of the place from which the module
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originates. See `origin`_ above. Aside from the informational value,
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it is also used in module_repr(). In the case of a spec where
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it is also used in the module's repr. In the case of a spec where
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"has_location" is true, ``__file__`` is set to the value of "origin".
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For built-in modules "origin" would be set to "built-in".
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@ -655,7 +650,7 @@ Simply setting loader_state or adding functionality to a custom
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finder or loader will likely be a better fit and should be tried first.
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However, as long as a subclass still fulfills the requirements of the
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import system, objects of that type are completely fine as the return
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value of Finder.find_spec().
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value of Finder.find_spec(). The same points apply to duck-typing.
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Existing Types
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@ -695,7 +690,7 @@ the cost until later.
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**PathEntryFinder.find_spec(name)**
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Finders will return ModuleSpec objects when find_spec() is
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Finders must return ModuleSpec objects when find_spec() is
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called. This new method replaces find_module() and
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find_loader() (in the PathEntryFinder case). If a loader does
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not have find_spec(), find_module() and find_loader() are
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@ -715,8 +710,9 @@ Currently a path entry finder may return (None, portions) from
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find_loader() to indicate it found part of a possible namespace
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package. To achieve the same effect, find_spec() must return a spec
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with "loader" set to None (a.k.a. not set) and with
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submodule_search_locations set to the same portions as were provided by
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find_loader(). It's up to PathFinder how to handle such specs.
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submodule_search_locations set to the same portions as would have been
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provided by find_loader(). It's up to PathFinder how to handle such
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specs.
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Loaders
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-------
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@ -777,6 +773,11 @@ Other Changes
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* The various finders and loaders provided by importlib will be
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updated to comply with this proposal.
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* Any other implmentations of or dependencies on the import-related APIs
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(particularly finders and loaders) in the stdlib will be likewise
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adjusted to this PEP. While they should continue to work, any such
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changes that get missed should be considered bugs for the Python 3.4.x
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series.
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* The spec for the ``__main__`` module will reflect how the interpreter
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was started. For instance, with ``-m`` the spec's name will be that
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of the run module, while ``__main__.__name__`` will still be
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