On Fri, 4 Jun 2010 12:26:20 -0400
Tino Dai <[email protected]> wrote:
> Also could you give me some instances
> where a generator
> would be used in a real situation? I have already read the stuff on
> doc.python.org about
> generators.
Sure, generally speaking in the programming world, documentation misses the
first and principle step: *purpose* :-) Why is that stuff intended for?
My point of view is as follows (I don't mean it's _the_ answer):
Generators are useful when not all potential values need be generated (or
possibly not all). Meaning you perform some task until a condition is met, so
you don't need all possible map values. A mapping or list comprehension instead
always creates them all.
A particuliar case where a generator is necessary is the one of an "open",
unlimited, series, defined by eg a formula, such as cubes. Such a potentially
infinite series is only broken by a loop break:
def cubes(first):
n = first
while True:
yield n ** 3
n += 1
for cube in cubes(1):
if cube > 999:
break
else:
print(cube),
Denis
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