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.
It is now possible to use a custom type for the __builtins__ namespace, instead
of a dict. It can be used for sandboxing for example. Raise also a NameError
instead of ImportError if __build_class__ name if not found in __builtins__.
Add INCREFs, fix args->kwargs, and a second args==NULL check was removed,
left over from a merger with another function. Instead, checking msg==NULL
does what that used to do in a roundabout way.
__loader__.
Since import now sets __loader__ on all modules it creates and
imp.reload() already relied on the attribute for modules that import
didn't create, the only potential compatibility issue is if people
were deleting the attribute on modules and expecting imp.reload() to
continue to work.
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__().
Currently import does not use these attributes as they are planned
for use by importlib (which will be another commit).
Thanks to Filip Gruszczyński for the initial patch and Brian Curtin
for refining it.