[Python-Dev] Type hints -- a mediocre programmer's reaction

[Guido van Rossum]

On Tue, Apr 21, 2015 at 12:49 AM, Antoine Pitrou <solipsis at pitrou.net>
wrote:

> On Mon, 20 Apr 2015 20:43:38 -0400
> "R. David Murray" <rdmurray at bitdance.com> wrote:
> > +1 to this from me too. I'm afraid that means I'm -1 on the PEP.
> >
> > I didn't write this in my earlier email because I wasn't sure about it,
> > but my gut reaction after reading Harry's email was "if type annotations
> > are used in the stdlib, I'll probably stop contributing".  That doesn't
> > mean that's *true*, but that's the first time I've ever had that
> > thought, so it is probably worth sharing.
>
> I think it would be nice to know what the PEP means for daily stdlib
> development. If patches have to carry typing information each time they
> add/enhance an API that's an addition burden. If typing is done
> separately by interested people then it sounds like it wouldn't have
> much of an impact on everyone else's workflow.
>

This point will be moot until new code appears in the stdlib whose author
likes type hints. As I said, we won't be converting existing code to add
type hints (I'm actively against that for the stdlib, for reasons I've
explained already).

*If* type hints prove useful, I expect that adding type hints **to code
that deserves them** is treated no different in the workflow than adding
tests or docs. I.e. something that is the right thing to do because it has
obvious benefits for users and/or future maintainers. If at some point
running a type checker over the stdlib as part of continuous integration
become routine, type hints can also replace certain silly tests.

Until some point in a possible but distant future when we're all thinking
back fondly about the argument we're currently having, it will be the
choice of the author of new (and *only* new) stdlib modules whether and how
to use type hints. Such a hypothetical author would also be reviewing
updates to "their" module and point out lack of type hints just like you
might point out an incomplete docstring, an outdated comment, or a missing
test. (The type checker would be responsible for pointing out bugs. :-P )

-- 
--Guido van Rossum (python.org/~guido)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-dev/attachments/20150421/56c9f0c9/attachment.html>