Francis Girard wrote:
Le dimanche 13 FÃvrier 2005 23:58, Terry Reedy a Ãcrit :
Iterators are a subgroup of iterables. Being able to say iter(it) without
having to worry about whether 'it' is just an iterable or already an
iterator is one of the nice features of the new iteration design.
I have difficulties to represent an iterator as a subspecie of an iteratable
... One of the result of not distinguishing them is that, at some point in
your programming, you are not sure anymore if you have an iterator or an
iteratable ; and you might very well end up calling "iter()" or "__iter__()"
everywhere.
The point is _almost_, but not exactly unlike that.
Because the "for ... in ..." construct calls iter itself, you seldom
need (as a code user) to distinguish between iterators and iterables.
However, there will come a day when you see some code like:
first = True
for blunge in whatever:
if first:
first = False
else:
print 'and',
print blunge
And you think, "I can make that clearer," so you write:
source = iter(whatever)
print source.next()
for blunge in source:
print 'and', blunge
Because of how iterables work, you know you can do this locally
without looking all around to see what "whatever" is.
--Scott David Daniels
[EMAIL PROTECTED]
--
http://mail.python.org/mailman/listinfo/python-list
