【python库】functools

开发环境为WIN10+Python 3.6.5，直接上代码，看注释

wraps

from functools import wraps


def run1(f):
    @wraps(f)
    def wrapper(*args, **kwargs):
        """run1.wrapper's doc"""
        return f(*args, **kwargs)
    return wrapper


@run1
def main1():
    """main1's doc"""
    pass


def run2(f):
    def wrapper(*args, **kwargs):
        """run2.wrapper's doc"""
        return f(*args, **kwargs)
    return wrapper


@run2
def main2():
    """main2's doc"""
    pass


print(main1.__name__)
print(main2.__name__)
print(main1.__doc__)
print(main2.__doc__)

结果是：

main1
wrapper
main1's doc
run2.wrapper's doc

偏函数 partial

from functools import partial


def fun(a, b=1, *args, **kwargs):
    print(a, b, args, kwargs)


p = partial(fun, 1, 2, 3, 4, 5, 6, 7, 8, c=9)
p()
print(p.args)
print(p.func)
print(p.keywords)

结果是：

1 2 (3, 4, 5, 6, 7, 8) {'c': 9}
(1, 2, 3, 4, 5, 6, 7, 8)
<function fun at 0x000001BDB9AC1EA0>
{'c': 9}

如果是类里面的方式，使用partialmethod

singledispath

from functools import singledispatch


@singledispatch
def fun(arg):
    print('string:', arg)


@fun.register(int)
def _(arg):
    print('int:', arg)


@fun.register(list)
def _(arg):
    print('list:', arg)


def nothing(arg):
    print('nothing')


fun.register(type(None), nothing)


print(fun.registry.keys())

fun('Hello')
fun(1)
fun([1, 2, 4])
fun(None)

注意，python没有所谓的函数重载，上面的方式，都只能针对函数的第一个参数有效。