fromlist of __import__ propagate.
The problem previously was that if something listed in fromlist didn't
exist then that's okay. The fix for that was too broad in terms of
catching ImportError.
The trick with the solution to this issue is that the proper
refactoring of import thanks to importlib doesn't allow for a way to
distinguish (portably) between an ImportError because finders couldn't
find a loader, or a loader raised the exception. In Python 3.4 the
hope is to introduce a new exception (e.g. ModuleNotFound) to make it
clean to differentiate why ImportError was raised.
When the fromlist argument is specified for __import__() and the
attribute doesn't already exist, an import is attempted. If that fails
(e.g. module doesn't exist), the ImportError will now be silenced (for
backwards-compatibility). This *does not* affect
``from ... import ...`` statements.
Thanks to Eric Snow for the patch and Simon Feltman for reporting the
regression.
state of the import system. Also make importlib.invalidate_caches()
work with sys.meta_path instead of sys.path_importer_cache to
completely separate the path-based import system from the overall
import system.
Patch by Eric Snow.
Lib/imp.py for imp.source_from_cache() instead of its own C version.
Also change PyImport_ExecCodeModuleObject() to not infer the source
path from the bytecode path like
PyImport_ExecCodeModuleWithPathnames() does. This makes the function
less magical.
This also has the side-effect of removing all uses of MAXPATHLEN in
Python/import.c which can cause failures on really long filenames.
statement (e.g. ``from distutils import msvc9compiler``) that triggers
an ImportError of its own (e.g. the non-existence of winreg), let that
exception propagate instead of raising a generic ImportError for the
module being requested (e.g. msvc9compiler).
importlib.abc.FileLoader.load_module()/get_filename() and
importlib.machinery.ExtensionFileLoader.load_module() have their
single argument be optional as the loader's constructor has all the
ncessary information.
This allows for the deprecation of
imp.load_source()/load_compile()/load_package().
This introduces a new function, imp.extension_suffixes(), which is
currently undocumented. That is forthcoming once issue #14657 is
resolved and how to expose file suffixes is decided.
importlib.util.module_for_loader also will set __loader__ along with
__package__. This is in conjunction to a forthcoming update to PEP 302
which will make these two attributes required for loaders to set.
be implicit.
Added a warning for when sys.path_hooks is found to be empty. Also
changed the meaning of None in sys.path_importer_cache to represent
trying sys.path_hooks again (an interpretation of previous semantics).
Also added a warning for when None was found.
The long-term goal is for None in sys.path_importer_cache to represent
the same as imp.NullImporter: no finder found for that sys.path entry.
importlib.machinery.(FileFinder, SourceFileLoader,
_SourcelessFileLoader, ExtensionFileLoader).
This exposes all of importlib's mechanisms that will become public on
the sys module.
for performance. While get_magic() could move to Lib/imp.py, having to
support PyImport_GetMagicNumber() would lead to equal, if not more, C
code than sticking with the status quo.
rewriting functionality in pure Python.
To start, imp.new_module() has been rewritten in pure Python, put into
importlib (privately) and then publicly exposed in imp.
of sys.modules when possible.
This is being done for two reasons. One is to gain a little bit of
performance by skipping an unnecessary dict lookup in sys.modules. But
the other (and main) reason is to be a little bit more clear in how
things should work from the perspective of import's interactions with
loaders. Otherwise loaders can easily forget to return the module even
though PEP 302 explicitly states they are expected to return the module
they loaded.
importlib._bootstrap is now frozen into Python/importlib.h and stored
as _frozen_importlib in sys.modules. Py_Initialize() loads the frozen
code along with sys and imp and then uses _frozen_importlib._install()
to set builtins.__import__() w/ _frozen_importlib.__import__().
Antoine Pitrou
Brett Cannon
Nick Coghlan
Philip Jenvey
Martin v. Löwis
Amaury Forgeot d'Arc
Eric V. Smith
Benjamin Peterson
Marc-Andre Lemburg