[Python-Dev] Lockstep iteration - eureka! (original) (raw)

Paul Prescod paul@prescod.net
Wed, 16 Aug 2000 00:30:06 -0400

Tim Peters wrote:

... But if you add seq.items(), you had better add seq.keys() too, and seq.values() as a synonym for seq[:]. I guess the perceived advantage of adding seq.items() is that it supplies yet another incredibly slow and convoluted way to get at the for-loop index? "Ah, that's the ticket! Let's allocate gazillabytes of storage and compute all the indexes into a massive data structure up front, and then we can use the loop index that's already sitting there for free anyway to index into that and get back a redundant copy of itself!" . not-a-good-sign-when-common-sense-is-offended-ly y'rs - tim

.items(), .keys(), .values() and range() all offended my common sense when I started using Python in the first place. I got over it.

I really don't see this "indexing" issue to be common enough either for special syntax OR to worry alot about efficiency. Nobody is forcing anyone to use .items(). If you want a more efficient way to do it, it's available (just not as syntactically beautifu -- same as range/xrangel).

That isn't the case for dictionary .items(), .keys() and .values().

Also, if .keys() returns a range object then theoretically the interpreter could recognize that it is looping over a range and optimize it at runtime. That's an alternate approach to optimizing range literals through new byte-codes. I don't have time to think about what that would entail right now.... :(

-- Paul Prescod - Not encumbered by corporate consensus Simplicity does not precede complexity, but follows it. - http://www.cs.yale.edu/homes/perlis-alan/quotes.html