[Python-Dev] Very Strange Argument Handling Behavior

[Maciej Fijalkowski]

On Fri, Apr 16, 2010 at 3:11 PM, Raymond Hettinger
<raymond.hettinger at gmail.com> wrote:
>
>>> Guido van Rossum, 16.04.2010 16:33:
>>>>
>>>> I am fine with
>>>> declaring dict({}, **{1:3}) illegal, since after all it is abuse of
>>>> the ** mechanism.
>
> ISTM that making it illegal costs cycles with giving any real benefit.
> It is reasonably common to accept **kwds and then pass it down
> to another function.  Do we want to validate the keys of every
> kwds dict on every call?  Why do we even care?
>
> If I'm understanding the proposal correctly, it means that
> every existing application using **kwds will pay a price, either
> by breaking (because it uses non-string keys) or by running
> slower (so that every call can be checked to make sure it
> didn't use string keys).
>
>
> Raymond
>

On the other hand, we (as in alternative python implementations) are
paying the price because people use it, even if only accidentally. If
CPython detects such cases and complain early, it would be much easier
for applications to stay cross-interpreter compatible (and I don't
think it's a huge burden for them to get rid of that, django already
did).

Cheers,
fijal