[issue16489] importlib find_loader returns a loader for a non existent module
Xavier de Gaye added the comment:
I was bitten by this behavior while, new to the importlib library, I
was trying to understand if one has to call recursively find_loader
for a dotted module name (in the way it must be done when using
imp.find_module), since the documentation on find_loader is not
clear. My test environment happened to be at that time:
foo.py
mypackage
__init__.py
foo.py
and at first I could not understand why find_loader('mypackage.foo')
was returning a loader, while find_loader('logging.handlers') was
returning None.
It is fine with me to consider that this behavior does not have
to be changed and to close this discussion.
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[issue16489] importlib find_loader returns a loader for a non existent module
Roundup Robot added the comment: New changeset 358be7742377 by Brett Cannon in branch '3.3': Issue #16489: Make it clearer that importlib.find_loader() requires http://hg.python.org/cpython/rev/358be7742377 New changeset ba1d7447bd1b by Brett Cannon in branch 'default': Merge fix for #16489 from 3.3 http://hg.python.org/cpython/rev/ba1d7447bd1b -- nosy: +python-dev ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue16489] importlib find_loader returns a loader for a non existent module
Brett Cannon added the comment: I clarified the wording in 3.3 and default. I also opened issue #16492 to add a keyword-only argument to find_loader() to have it import parent packages for you if you so desire. -- resolution: invalid - fixed stage: - committed/rejected ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue16489] importlib find_loader returns a loader for a non existent module
Xavier de Gaye added the comment: Thanks, this is great! -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue16489] importlib find_loader returns a loader for a non existent module
New submission from Xavier de Gaye:
Create the following tree:
foo.py
mypackage
__init__.py
and get a loader for the non existent module 'mypackage.foo'.
$ mkdir tmp
$ cd tmp
$ foo.py
$ mkdir mypackage
$ mypackage/__init__.py
$ ./python
Python 3.4.0a0 (default:53a7c2226a2b, Nov 9 2012, 16:47:41)
[GCC 4.3.2] on linux
Type help, copyright, credits or license for more information.
import importlib
importlib.find_loader('mypackage').get_filename()
'./mypackage/__init__.py'
importlib.find_loader('mypackage.foo').get_filename()
'./foo.py'
find_loader should return None in this case.
--
components: Library (Lib)
messages: 175697
nosy: xdegaye
priority: normal
severity: normal
status: open
title: importlib find_loader returns a loader for a non existent module
type: behavior
versions: Python 3.4
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[issue16489] importlib find_loader returns a loader for a non existent module
Xavier de Gaye added the comment:
And yes, find_loader returns None, when correctly invoked with the
path argument:
importlib.find_loader('mypackage.foo', ['./mypackage/'])
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[issue16489] importlib find_loader returns a loader for a non existent module
R. David Murray added the comment: Not necessarily. The fact that there is nothing to load doesn't mean it isn't the right loader if there *was* something to load. But I'll leave it to the import experts to say what the expected behavior is. I'll admit that I can't figure it out from a quick perusal of the docs and PEP, so I'd say that regardless of what the correct behavior is there is at least a doc bug here. -- nosy: +brett.cannon, eric.smith, r.david.murray ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue16489] importlib find_loader returns a loader for a non existent module
Brett Cannon added the comment:
Everything is working as expected; you left out the path argument::
importlib.find_loader('package.foo', ['package'])
This works the way it does because otherwise we would have to stat every single
time from the top level on down and that is extremely costly.
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resolution: - invalid
status: open - closed
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[issue16489] importlib find_loader returns a loader for a non existent module
Xavier de Gaye added the comment: Maybe find_loader could check its parameters, notice that the name is a dotted name, that path is None and in this case, not return a loader ? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue16489] importlib find_loader returns a loader for a non existent module
Brett Cannon added the comment: That won't work as frozen and builtin modules don't care about the path. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue16489] importlib find_loader returns a loader for a non existent module
Xavier de Gaye added the comment: Not necessarily. The fact that there is nothing to load doesn't mean it isn't the right loader if there *was* something to load. But it is not even the right loader if there *was* something to load, as get_filename() returns './foo.py' which is wrong even if mypackage/foo.py had existed. It should have returned './mypackage/foo.py' to be an acceptable loader for a would-be mypackage.foo module. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue16489] importlib find_loader returns a loader for a non existent module
Xavier de Gaye added the comment: If one would want to fix this, one way to do it could be to change the following two methods of the PathFinder class such that: find_module() does not set path to sys.path when its path argument is None, so as to keep this information for _get_loader() to process it later _get_loader() sets path to sys.path when its path argument is None and returns a None loader when a loader has been found by a finder and: - this finder is a FileFinder instance - the _get_loader() path argument is None - the module name is a dotted name -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue16489] importlib find_loader returns a loader for a non existent module
Brett Cannon added the comment: Feel free to submit a patch, but I'm personally not motivated enough to try to change this on my own. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue16489] importlib find_loader returns a loader for a non existent module
Eric V. Smith added the comment: It might be more motivating if you (Xavier de Gaye) could let us know of a real-world problem caused by this behavior. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue16489 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
