[Python-3000] set literals

[Guido van Rossum]

Hm. Your objections seem to be purely from a performance tuning POV. I
think that if we agree that API-wise this is an improvement (fewer
things to learn, set literals problem solved, and dicts grow some
useful new methods) we should make a decision to do it and damn the
tuning (I trust Raymond will find a way :-).

--Guido

On 7/17/06, Michael Chermside <mcherm at mcherm.com> wrote:
> Guido writes:
> > I've also sometimes thought of unifying dicts and sets by implementing
> > set operations on the keys of dicts only.
>     [... much discussion ...]
> > I'm still very much undecided but I don't want to rule this out for
> > py3k. Perhaps I'll write up a PEP and see how it flies.
>
> Playing with it, and PEPing it both sound fine, but I think DOING it
> seems like a bad idea.
>
> I see two advantages. One is public: it solves the issue of a set
> literal. The other is private: it allows us to reuse the implementation.
>
> Fixing the set literal just isn't sufficient justification, IMHO. And
> as for the implementation, we care VERY much about perfectly tuning
> the performance of the dict type, because its performance is so key to
> the implementation of namespaces throughout Python. So I would not want
> to accept any unnecessary restrictions on the implementation that might
> constrain future optimizations of dict performance.
>
> Besides, how difficult is it to maintain the existing C implementation
> of set and frozenset (now that they're written and have been through
> the wringer of being in a production release). It's not zero cost, but
> it's also probably not THAT big.
>
> Of course, that's the idea behind trying it out and even writing a PEP
> -- then we'll see whether my guess (or yours!) is correct.
>
> -- Michael Chermside
>


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