Python的functools模块使用及说明

from functools import partial

int2 = partial(int, base=8)
print(int2('123'))
# 83

from functools import update_wrapper
def wrap2(func):
    def inner(*args):
        return func(*args)
    return update_wrapper(inner, func)

@wrap2
def demo():
    print('hello world')

print(demo.__name__)
# demo

from functools import wraps
def wrap1(func):
    @wraps(func)    # 去掉就会返回inner
    def inner(*args):
        print(func.__name__)
        return func(*args)
    return inner

@wrap1
def demo():
    print('hello world')

print(demo.__name__)
# demo

reduce(function, sequence, startValue)

from functools import reduce

l = range(1,50)
print(reduce(lambda x,y:x+y, l))
# 1225

x = ['hello','worl','ni']
x.sort(key=len)
print(x)
# ['ni', 'worl', 'hello']

from functools import lru_cache
@lru_cache(maxsize=30)  # maxsize参数告诉lru_cache缓存最近多少个返回值
def fib(n):
    if n < 2:
        return n
    return fib(n-1) + fib(n-2)
print([fib(n) for n in range(10)])
fib.cache_clear()   # 清空缓存

from functools import singledispatch
@singledispatch
def fun(text):
    print('String：' + text)

@fun.register(int)
def _(text):
    print(text)

@fun.register(list)
def _(text):
    for k, v in enumerate(text):
        print(k, v)

@fun.register(float)
@fun.register(tuple)
def _(text):
    print('float, tuple')
fun('i am is hubo')
fun(123)
fun(['a','b','c'])
fun(1.23)
print(fun.registry)    # 所有的泛型函数
print(fun.registry[int])    # 获取int的泛型函数
# String：i am is hubo
# 123
# 0 a
# 1 b
# 2 c
# float, tuple
# {<class 'object'>: <function fun at 0x106d10f28>, <class 'int'>: <function _ at 0x106f0b9d8>, <class 'list'>: <function _ at 0x106f0ba60>, <class 'tuple'>: <function _ at 0x106f0bb70>, <class 'float'>: <function _ at 0x106f0bb70>}
# <function _ at 0x106f0b9d8>