装饰器举例

定义：本质上是函数，（装饰其他函数）就是为其他函数添加附件功能

原则：
不能修改被装饰函数的源代码
不能修改被装饰函数的调用方式

举例：把current_time,还有distance_current_time合成一个函数和装饰器

#auther:Summer-yang
#datetime:2022/4/18 14:44
import datetime
import re

UTC_FORMAT = '%Y-%m-%dT%H:%M:%SZ'
def current_time(hours=None,time_format = None):
    """
    N hours ahead of current time
    """
    current = datetime.datetime.utcnow()
    if hours:
        if isinstance(hours,int):
            current = current - datetime.timedelta(hours=hours)
        elif isinstance(hours,str):
            current = current - datetime.timedelta(hours=int(hours))
    if time_format:
        tm_format = time_format
    else:
        tm_format = UTC_FORMAT
    d1 = current.strftime(tm_format)
    return d1

def decorator(func):
    def wrapper(times,time_format=None):
        if isinstance(times,int):
            distance_time = func(times,time_format)
            return distance_time
        else:
            tes = re.search('(\d*)h$',times)
            if tes.group():
                current = datetime.datetime.utcnow()
                current = current - datetime.timedelta(hours=int(tes.group(1)))
                if time_format:
                    tm_format = time_format
                else:
                    tm_format = UTC_FORMAT
                return current.strftime(tm_format)
    return wrapper

@decorator
def  distance_current_time(num,time_format = None):
    """num days from the current time,

    Args:
        num ([type]): how many days is it from now
        time_format: time format ,like:time_format = "%Y-%m-%d"
    Returns:
        [type]: [description]
    """
    if time_format:
        tm_format = time_format
    else:
        tm_format ="%Y-%m-%d"
    distance_time = (datetime.datetime.now() -datetime.timedelta(days=-int(num))).strftime(tm_format)
    return distance_time

if __name__ == '__main__':
    print(current_time(1))
    print(distance_current_time(0))
    print(distance_current_time('1h'))