[Python-Dev] Re: PEP 279 (original) (raw)

James Althoff jamescalthoff@yahoo.com
Thu, 4 Apr 2002 11:33:13 -0800

Trying again without all the nasty HTML -- apologies to all.

[David Abrahams]

. . . I want to put in another plug for itemize(),

Well, since we're doing post-Pronouncement fantasizing . . .

here's one more plug for "itemize".

Noting that

for k,v in adict.iteritems():

is probably as useful as

for i,v in enumerate(aseq):

why not change the spec to:

def itemize(iterable): ... # use iteritems if defined ... try: ... for item in iterable.iteritems(): yield item ... except AttributeError: pass ... # and then everything as before ... i = 0 ... iterator = iter(iterable) ... while 1: ... yield i,iterator.next() ... i += 1 ...

So "itemize(iterable)" returns an iterator that yields (k,v) pairs from the iterable.iteritems() method if defined, else pairs generated by associating 0,1,...,n-1 with n values from iter(iterable).

This allows

for k,v in itemize(adict_or_aseq):

to be written uniformly for dicts and seqs.

And makes

list(itemize(adict)) == adict.items()

work, removing one of the objections to the name "itemize".

Also, if one were to need, for example, a sequence whose indices start at 1 instead of 0, one could define a sequence class that implements iteritems and objects of said class would work just fine with "itemize".

Jim