Chris Angelico wrote: > On Tue, Aug 29, 2017 at 4:59 AM, Stefan Ram <r...@zedat.fu-berlin.de> > wrote: >> This might be what one calls "heisenbug": >> >> No attribute 'abc' is visible. One tries to >> study it with "help". And next time it's there. >> "help" /did/ help! >> >> Python 3.6.0 ... >> >>>>> import collections >> >>>>> isinstance( 'abc', collections.abc.Sequence ) >> Traceback (most recent call last): >> File "<stdin>", line 1, in <module> >> AttributeError: module 'collections' has no attribute 'abc' >> >>>>> help(collections) >> Help on package collections: ... >> >>>>> isinstance( 'abc', collections.abc.Sequence ) >> True > > When you import "collections", you load up the package. If anything > subsequently runs "import collections.abc", the module gets loaded, > and is visible from the package. The help function does exactly that > import. It's a bit surprising but only an issue with interactive work. > (You won't use help() elsewhere.)
The lesson is that if you use a (sub)module you should never rely on an implicit import. -- https://mail.python.org/mailman/listinfo/python-list
