[Python-Dev] Some comments on PEP 328 (absolute/relative imports) (original) (raw)

Aahz aahz at pythoncraft.com
Tue Apr 6 10:16:15 EDT 2004

On Tue, Apr 06, 2004, Barry Warsaw wrote:

On Sat, 2004-04-03 at 13:24, Bernhard Herzog wrote:

I don't think this is a good description of the actual problem. The problem is that the modules in the package shadow global ones and there's no easy way to bypass the local package. FWIW, though, I don't recall ever running into a problem with that. It happens, and it makes for tricky choices. I know to stay away from internal modules like re and email, but as the standard library gets fatter, there's more chance of collision. The only remedy will be to rename an internal module when I find that I suddenly want to use some new standard module. There should be more independence.

Thanks! Here's my rewrite; comments, anyone?

Rationale for Absolute Imports

In Python 2.3 and earlier, if you're reading a module located inside a package, it is not clear whether ::

import foo

refers to a top-level module or to another module inside the package. As Python's library expands, more and more old modules suddenly shadow builtin modules by accident. It's a particularly difficult problem inside packages because there's no way to specify which module is meant. To resolve the ambiguity, it is proposed that foo will always be a module or package reachable from sys.path. This is called an absolute import.

The python-dev community chose absolute imports as the default because they're the more common use case and because absolute imports can provide all the functionality of relative (intra-package) imports -- albeit at the cost of difficulty when renaming package pieces higher up in the hierarchy or when moving one package inside another.

Aahz (aahz at pythoncraft.com) <*> http://www.pythoncraft.com/

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