[Python-Dev] Relative import (original) (raw)

Guido van Rossum guido at python.org
Tue Dec 16 13:26:59 EST 2003

A lot people have presented a good case for relative imports. Nobody has argued to keep the status quo (where imports are ambiguous about whether they are meant to be absolute or relative). So I suggest that in 2.4, we introduce the leading dot notation for relative import, while still allowing relative import without a leading dot. In 2.5 we can start warning about relative import without a leading dot (although that will undoubtedly get complaints from folks who have code that needs to work with 2.3 still). In 3.0 we can retire ambiguous import.

The use case for multiple dots should be obvious: inside a highly structured package, modules inside one subpackage must have a way to do relative import from another subpackage of the same parent package.

There is the remaining issue of what exactly the syntax would be. I propose to extend the from clause to allow one or more dots before the dotted name, and to make the dotted name optional if at least one leading dot is found. I propose not to change from-less import. Examples:

from .foo import bar from .foo.bar import xxx from . import foobar as barfoo from ..foo.bar import * from ... import foobar, barfoo

Grammar change (see Grammar/Grammar):

dotted_name: NAME ('.' NAME)* | '.'+ [NAME ('.' NAME)*]

--Guido van Rossum (home page: http://www.python.org/~guido/)

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