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.