[Python-Dev] PEP 289 - Generator Expressions (original) (raw)

[Python-Dev] PEP 289 - Generator Expressions - Let's Move Forward

Armin Rigo arigo at tunes.org
Sat May 1 03:08:48 EDT 2004

Hello Guido,

On Fri, Apr 30, 2004 at 04:12:59PM -0700, Guido van Rossum wrote:

That's not new, we all know that that's the downside of late binding.

My counter to that is that any use of genexps where the consumer doesn't consume (or discard) the iterator before the next line is reached is extremely advanced use.

My argument was that late-binding make it even more mysterious, not less suprizing, because in the minority of cases where a listcomp is not used immediately but still need a genexpr for performance, you have to think carefully.

Well, I insist a bit because I cannot helping thinking that the arguments for early-binding are "that's useful in a very small number of cases", and the arguments for late-binding are "you don't want to do that anyway so let's pick the semantic of free vars in functions". I don't immediately think of genexps as similar to functions, rather closer to listcomps, even if I know that they are functions under the hood.

Armin

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