example-code-2e/08-def-type-hints/sample.py
2021-08-07 00:44:01 -03:00

36 lines
756 B
Python

# tag::SAMPLE[]
from collections.abc import Sequence
from random import shuffle
from typing import TypeVar
T = TypeVar('T')
def sample(population: Sequence[T], size: int) -> list[T]:
if size < 1:
raise ValueError('size must be >= 1')
result = list(population)
shuffle(result)
return result[:size]
# end::SAMPLE[]
def demo() -> None:
import typing
p1 = tuple(range(10))
s1 = sample(p1, 3)
if typing.TYPE_CHECKING:
reveal_type(p1)
reveal_type(s1)
print(p1)
print(s1)
p2 = 'The quick brown fox jumps over the lazy dog'
s2 = sample(p2, 10)
if typing.TYPE_CHECKING:
reveal_type(p2)
reveal_type(s2)
print(p2)
print(s2)
if __name__ == '__main__':
demo()