[issue11374] pkgutil.extend_path do not recognize py{c,o} file

[Barry A. Warsaw]

Barry A. Warsaw <barry at python.org> added the comment:

On Nov 29, 2011, at 12:50 PM, Éric Araujo wrote:

>Before you put more work into this, it would be nice to get confirmation from
>one import expert that the bug is valid: I know the import system only
>superficially, and I’m not sure that package/__init__.pyc / .pyo is supported
>by import (if not, then pkgutil should also not support it).

It's an interesting question.  Under Python 2, I'd say yes, it should support
source-less imports, just as Python does.  Under Python 3, with PEP 3147, I'm
not so sure:

$ cat > foo.py
print('hello world')
$ cat > bar.py
import foo
$ ls
bar.py	foo.py
$ python3 bar.py
hello world
$ ls
bar.py	foo.py	__pycache__/
$ ls __pycache__/
foo.cpython-32.pyc
$ rm -f foo.py
$ python3 bar.py
Traceback (most recent call last):
  File "bar.py", line 1, in <module>
    import foo
ImportError: No module named foo

Then:

$ mv __pycache__/foo.cpython-32.pyc foo.pyc
$ ls
bar.py	foo.pyc  __pycache__/
$ python3 bar.py
hello world

So Python 3 source-less imports are still supported, but only when legacy
.pyc/.pyo locations are explicitly used.

My inclination is then -0 on extend_path() supporting .pyc/.pyo but only
*outside* the context of PEP 3147.  I.e. do not use imp.cache_from_source().

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