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

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

Jeremy Hylton jeremy at alum.mit.edu
Mon May 3 22:42:53 EDT 2004

On Mon, 2004-05-03 at 09:58, Jewett, Jim J wrote:

Guido van Rossum:

> 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. This might be worth putting in the PEP and the docs --

We are in rather dire need of docs and a revised PEP.

Normal usage of a generator expression is to immediately consume the entire sequence, or to discard the remainder.

If portions of a generator are used later, programmers may need some extra precautions to ensure that all names still have the desired bindings.

There may be a general rule that functions that make use of free variables are best programmed in a functional style, where the function doesn't depend on side-effects to those variables.

Jeremy

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