how to use iterator in while loop statement in python

Question

Is it possible to use a generator or iterator in a while loop in Python? For example, something like:

i = iter(range(10))
while next(i):
    # your code

The point of this would be to build iteration into the while loop statement, making it similar to a for loop, with the difference being that you can now additional logic into the while statement:

i = iter(range(10))
while next(i) and {some other logic}:
    # your code

It then becomes a nice for loop/while loop hybrid.

Does anyone know how to do this?

Answer 1

In Python >= 3.8, you can do the following, using assignment expressions:

i = iter(range(10))
while (x := next(i, None)) is not None and x < 5:
    print(x)

In Python < 3.8 you can use itertools.takewhile:

from itertools import takewhile

i = iter(range(10))
for x in takewhile({some logic}, i):
    # do stuff

"Some logic" here would be a 1-arg callable receciving whatever next(i) yields:

for x in takewhile(lambda e: 5 > e, i):
    print(x)
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