[Python-Dev] PEP 8 updates/clarifications

[Guido van Rossum]

On 12/12/05, skip at pobox.com <skip at pobox.com> wrote:
>
>     >> I looked at that too, but most of these didn't jump out at me.  I'll
>     >> copy in the parts that aren't already in PEP 8 that seem possible:
>     >>
>     >> From-imports should follow non-from imports.  Dotted imports should
>     >> follow non-dotted imports.  Non-dotted imports should be grouped by
>     >> increasing length, while dotted imports should be grouped roughly
>     >> alphabetically.
>     >> This seems too complex to me for PEP 8.
>
>     Barry> Really?  ISTR adopting this convention from Guido, but I'm not
>     Barry> 100% sure about that.  After having used it for several years
>     Barry> now, I do really like this style, but I'm willing to leave the
>     Barry> recommendation out of PEP 8.
>
> This is subjective enough that I would think some rationale explaining this
> convention should be given.  Personally, I group imports into three sections
> as follows:
>
>     * Python core modules/packages
>
>     * Third-party modules/packages
>
>     * Local modules/packages
>
> I can't explain why I do it that way.  I guess it just satisfies some inner
> hobgoblin.

This is what I recommend too, and PEP 8 should recommend this.

While I admit to a kind of secret enjoyment when I see the standard
library module imports arranged by increasing length, I don't think
that ought to be put in the PEP. (I remember once seeing a friend's
books arranged by size on their shelves and finding it bizarre. You
should have the same feeling when you see imports arranged that way.)
A more rational approach would be to do them alphabetically.

Putting the from...import ones last makes sense if only because it's
not obvious where they fit in the alphabetization.

Dotted non-from imports (e.g. import test.pystone) are rare enough
that they don't deserve a special rule; if you want me to give a rule,
I think they should be mixed in with the undotted ones,
alphabetically.

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