[Python-Dev] Possible resolution of generator expressionvariablecapture dilemma (original) (raw)

Raymond Hettinger python at rcn.com
Thu Mar 25 02:34:10 EST 2004

People never leave well enough alone, though, so I hope generator expressions don't become another "minor convenience" that's viewed as a "minor annoyance" a year later.

I do not view genexps as "convenient" short-forms for real generators. Instead, they represent memory/resource friendly versions of list comps which have been fabulously successful and have helped move us away from map/lambda forms. I believe they will make the language more fluid, cohesive, and expressive.

Once genexps are in, I think everyone will be pleasantly surprised at how readily the new gizmos work together and how easily they mesh with what was there before. Behind the scenes genexps will offer the added benefit of scalability, handling growing volumes of data without clobbering memory. So please, let's don't get any wild ideas about throwing the baby out with the bathwater.

In deciding on semantics, we would all rather trade away some power in exchange for greater clarity about what the expression will do without having to run it. Put another way, human interpretability is more important than supporting weird usages. With that criteria, early-binding is looking to be least nuanced approach.

wishing-i-was-in-DC-ly yours,

Raymond

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