[Python-Dev] Par-for/range

Paul Prescod paul@prescod.net
Wed, 12 Jul 2000 13:10:56 -0500

Thomas Wouters wrote:
> ...
> For that reason I think it's better to live with xrange() ;)

Thinking some more...

If we had first class range syntax then it would be relatively easy to
recognize the pattern

for i in [x:y:z]:

Then we could generate a special FOR_INTS bytecode. I've heard that "C"
has a pretty efficient implementation of that construct. <wink>

That would wipe out 96.3% of the need for xrange or tuplerange or
whatever you want to call it. We could probably deprecate both functions
and let the rare person who really wants an xrange use a class or
math.xrange() or mxtools.xrange() or a lazy list comprehension (if we
invent those!). 

Plus, if your loops are so large that they need xrange, you would
probably get an interesting speedup from using a real C for-loop instead
of an object! I mean for small values xrange is slower than range and
when you think about what range is doing under the covers. <shudder>

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