python 计算`str.format`模板中的占位符数

Posted 2021-05-09

import string

# Reference: https://stackoverflow.com/a/46161774/7881370
# Access data: 2019-03-23
def count_n_placeholders(template: str) -> int:
    return sum(1 for _ in filter(lambda x: x[1] is not None,
                                 string.Formatter().parse(template)))