[Python-bugs-list] [ python-Bugs-493628 ] import not pythonic in 2.1.1

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Bugs item #493628, was opened at 2001-12-15 03:37
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Category: Python Interpreter Core
Group: Not a Bug
Status: Closed
Resolution: Wont Fix
Priority: 5
Submitted By: Chris Withers (fresh)
Assigned to: Nobody/Anonymous (nobody)
Summary: import not pythonic in 2.1.1

Initial Comment:
Take a package 'aPackage', which contains a sub-package 'aSubPackage' that in turn contains a 
module 'aModule' that defines a class 'aClass'.

If I do:

import aPackage.aSubPackage
print aPackage.aSubPackage.aModule

I get:

Traceback (most recent call last):
  File "x.py", line xx, in ?
    print aPackage.aSubPackage.aModule
AttributeError: 'aPackage.aSubPackage' module has no attribute 'aModule'

A yet, if I do:

import aPackage.aSubPackage.aModule
print aPackage.aSubPackage.aModule

I get:
<module 'aPackage.aSubPackage.aModule' from 'some_path'>

...as expected, which is very confusing and doesn't feel 'right' :-S




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>Comment By: Guido van Rossum (gvanrossum)
Date: 2001-12-16 11:38

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OK, the motivation is that importing a package shouldn't
recursively import all its submodules -- else importing a
top-level package could do an immense amount of work.

The motivation for the thing you quote is less clear -- it
follows from the requirement that in "import <something>",
"<something>" refers to a module (where a package is a
special case of a module).

I'm not sure what to do with your whine about being one of
the many who find it counter-intuitive. Can you explain how
you would like it to behave?

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Comment By: Tim Peters (tim_one)
Date: 2001-12-16 10:03

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Chris, why do you think you need to use an exec stmt?  You 
haven't shown an example of why it's needed, and it sure 
isn't obvious.

Modules must be imported, and importing a module M requires 
an import stmt whose last path component is M -- that's 
about all there is to it.

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Comment By: Chris Withers (fresh)
Date: 2001-12-16 04:58

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Well, I read it, and it explains the history, but it doesn't give reasons, particularly for:

> Contrarily, when using syntax like import item.subitem.subsubitem, each item except for the last must be 
a package; the last item can be a module
> or a package but can't be a class or function or variable defined in the previous item. 

...or for the above stuff.

But, while I find it counter-intuitive (and means I have to use unpleasant exec statements), I am but one 
voice among many who probably feel differently so I'll just accept it as one of the things i don't like about 
python...

thanks for your time :-)

Chris


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Comment By: Guido van Rossum (gvanrossum)
Date: 2001-12-15 09:46

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http://www.python.org/doc/essays/packages.html

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Comment By: Chris Withers (fresh)
Date: 2001-12-15 09:15

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Okay, if it's intended, that means there's a good reason for it...

...where can I look for enlightenment as to what that is?

cheers,

Chris

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Comment By: Guido van Rossum (gvanrossum)
Date: 2001-12-15 07:39

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Better adjust your intuition. :-)

This is as intended. Attributes of packages that are
*modules* are only loaded when the corresponding module is
explicitly imported (by you, or by some other code, e.g. the
package's __init__.py).

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