[Tutor] Workaround for limitation in xrange()?

[Dick Moores]

At 12:31 PM 10/10/2006, Marc Poulin wrote:

>--- Dick Moores <rdm at rcblue.com> wrote:
> >
> > Andrei's
> > Write your own iterator:
> >  >>> def hugerange(minval, maxval):
> > ...     val = minval
> > ...     while val < maxval:
> > ...         yield val
> > ...         val += 1
> >
> > All 3 are essentially the same, aren't they. Which
> > makes me feel even
> > dumber, because I don't understand any of them. I've
> > consulted 3
> > books, and still don't understand the use of yield.
> >
>
>This is an example of a "coroutine".
>See http://en.wikipedia.org/wiki/Coroutine
>
>def hugerange(minval, maxval):
>     val = minval
>     while val < maxval:
>         yield val
>         ### return value of "val" to calling routine
>         ### at this point and place
>         ### hugerange() function temporarily
>         ### on hold ...
>         ###
>         ### next call to hugerange()
>         ### resumes at this point with
>         ### all previous variable values
>         ### still intact ...
>         val += 1

Ah, it's beginning to make sense. However, it seems there's a need to 
do this because the while loop is inside a function (made generator). 
The while loop of mine in 
<http://www.rcblue.com/Python/1histogram-5a-ForWeb.txt> is not in a 
function, so it seems I don't need a generator. Am I correct? I have 
a real interest in speed, however, and being forced to use the while 
loop for k larger than 2**31-1 really slows things down. It seems a 
while loop is about 20% slower than an equivalent for loop. Would 
using a generator be a help speedwise? I suspect it wouldn't. How about it?

Thanks very much, Marc.

Dick