[Python-3000] pep 3124 plans

[Guido van Rossum]

On 7/18/07, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
> Guido van Rossum wrote:
> > Sorry, but I'm still totally uncomfortable with this. While I admit
> > the feature exists, I really, really, really don't want it to be used
> > on a regular basis.
>
> As long as the objects defined by a regular def statement
> aren't modifiable, it seems like it won't be possible
> to support retroactive generification of functions that
> haven't initially been defined as generic somehow.
>
> So effectively you're saying that you're against this,
> or willing to forego it? Not arguing one way or the
> other, just seeking to clarify your position.

The only approach to retroactive generification that I approve of is
replacing the entire object with a wrapper of sorts, e.g.

  foo = generify(foo)

or (more likely)

  import bar
  bar.foo = generify(bar.foo)

I know this has a downside when someone else did "from bar import foo"
before the generification was applied; that is a general problem with
"from foo import bar" and should be addressed by not using that style
in cases where this matters. (It is fine for importing a submodule
from a package of course.)

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