[issue23447] Relative imports with __all__ attribute
Steven Barker added the comment: This issue is a special case of the problem discussed in issue 992389, that modules within packages are not added to the package dictionary until they are fully loaded, which breaks circular imports in the form from package import module. The consensus on that issue is that it doesn't need to be fixed completely, given the partial fix from issue 17636. I think the current issue is a corner case that was not covered by the fix, but which probably should be fixed as well, for consistency. The fix so far has made imports that name the module work, even though the module objects are still not placed into the package's namespace yet (this is why Antonio's last example works in the newly released 3.5a1, though not in previous versions). Wildcard imports however still fail. Can the fix be expanded to cover wildcard imports as well? I know, we're heaping up two kinds of usually-bad code (wildcard imports and circular imports) on top of one another, but still, the failure is very unexpected to anyone who's not read the bug reports. I don't know my way around the import system at all yet, so I'm not going to be capable of writing up a patch immediately, but if there's any interest at all, and nobody more knowledgeable gets to it first I might see what I can learn and try to put together something. Here's a more concise example of the issue: package/__init__.py: __all__ = [module] package/module.py: from . import module # this works in 3.5a1, thanks to the fix from issue 17636 from . import * # this still fails -- nosy: +Steven.Barker ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue23447 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue23447] Relative imports with __all__ attribute
Brett Cannon added the comment: If you put a print call after your `from . import *` call you will notice it never gets executed. Basically import is still in the middle of finishing imports when that import * is reached, including setting the module attributes on the package. Basically you have a circular import. -- nosy: +brett.cannon resolution: - not a bug status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue23447 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue23447] Relative imports with __all__ attribute
Antonio Cota added the comment:
I tried the following on python 3.5.0a1:
#init.py
__all__ = ['second', 'first']
print('i\'m starting the directory')
#first.py
print('hi, i\'m the first')
from . import second
#second.py
print('hi, i\'m the second')
from . import first
import a.first
i'm starting the directory
hi, i'm the first
hi, i'm the second
it just worked out perfectly, no errors.
But the case I show before still continues to get the AttributeError error.
You told me that basically it doesn't work because it is a circular import, but
isn't python already able to manage circular import?
What I expected when running the from . import * statament was Python looking
up in the __all__ attribute and import everything within it. When it had to
import 'first' I expected Python to check in the sys.modules to see if it was
already imported so, in this case, it could see that first.py was already
imported and no error was raised.
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[issue23447] Relative imports with __all__ attribute
Changes by Antonio Cota antocot...@gmail.com: -- versions: -Python 3.4 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue23447 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue23447] Relative imports with __all__ attribute
New submission from Antonio Cota:
That's the situation:
a/
__init__.py
first.py
second.py
#init.py
__all__ = ['second', 'first']
print('i\'m starting the directory')
#first.py
print('hi, i\'m the first')
from . import *
#second.py
print('hi, i\'m the second')
From the interactive prompt:
import a.first
i'm starting the directory
hi, i'm the first
hi, i'm the second
Traceback (most recent call last):
File stdin, line 1, in module
File /home/antox/Scrivania/a/first.py, line 2, in module
from . import *
AttributeError: module 'a' has no attribute 'first'
It's pretty weird.
--
messages: 235761
nosy: antox
priority: normal
severity: normal
status: open
title: Relative imports with __all__ attribute
type: behavior
versions: Python 3.5
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[issue23447] Relative imports with __all__ attribute
Changes by Antonio Cota antocot...@gmail.com: -- versions: +Python 3.4 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue23447 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
