AndyL wrote: > Paul Rubin wrote: >> Normally you'd use range or xrange. range builds a complete list in >> memory so can be expensive if the number is large. xrange just counts >> up to that number. > > so when range would be used instead of xrange. if xrange is more > efficient, why range was not reimplemented?
Because of backwards compatibility. range() returns a list, xrange() an iterator: list(xrange(...)) will give the same results as range(...). In for loops, using xrange instead of range makes no difference since the loop only iterates over the range. But it's a problem when someone just does l = range(100) and assumes that he's got a list, probably doing l.remove(5) and so on. In Python 3000, plans are that range() will be the same as xrange() is now, and anyone needing a list can call list(range(...)). Georg -- http://mail.python.org/mailman/listinfo/python-list
