Python While True Counter

Posted: 2021-03-04

I was recently trying to find a clean way of doing something like the following, except for a while True loop (without a known list_of_values up front)

for i, value in enumerate(list_of_values):
    do_something(i, value)

I was trying to paginate though an as yet unknown number of pages to be returned by an API

Something like this would work, but it seemed too verbose (3 lines to achieve my goal):

page = 1  # 1
all_page_data = []
while True:  # 2
    page_data = get_page_data(page=page)
    all_page_data.extend(page_data)
    if page_data == []:
        break
    page += 1  # 3

I ended up finding a nice alternative in the standard library itertools, which felt a bit cleaner (1 line, ignoring import)

import itertools

all_page_data = []
for page in itertools.count(start=1):  # 1
    page_data = get_page_data(page=page)
    all_page_data.extend(page_data)
    if page_data == []:
        break

Cleaning up to just the important info:

import itertools

for i in itertools.count(start=1):
    do_something(i)

    if condition:
        break