Cameron Laird <[EMAIL PROTECTED]> wrote: > In article <[EMAIL PROTECTED]>, > Alex Martelli <[EMAIL PROTECTED]> wrote: > . > . > . > >My preference would be (with the original definition for > >words_of_the_file) to code > > > > numwords = sum(1 for w in words_of_the_file(thefilepath)) > . > . > . > There are times when > > numwords = len(list(words_of_the_file(thefilepath)) > > will be advantageous.
Can you please give some examples? None comes readily to mind... > For that matter, would it be an advantage for len() to operate > on iterables? It could be faster and thriftier on memory than > either of the above, and my first impression is that it's > sufficiently natural not to offend those of suspicious of > language bloat. I'd be a bit worried about having len(x) change x's state into an unusable one. Yes, it happens in other cases (if y in x:), but adding more such problematic cases doesn't seem advisable to me anyway -- I'd evaluate this proposal as a -0, even taking into account the potential optimizations to be garnered by having some iterables expose __len__ (e.g., a genexp such as (f(x) fox x in foo), without an if-clause, might be optimized to delegate __len__ to foo -- again, there may be semantic alterations lurking that make this optimization a bit iffy). Alex -- http://mail.python.org/mailman/listinfo/python-list
