流程的python--第五章--一等函数

把函数视为对象

def fac(n):
    '''return n!'''
    return 1 if n<2 else n* fac(n-1)

fac.__doc__
#会打印出 return n!

#map使用，打印出前十一个阶乘的列表
list(map(fac, range(11)))
[fac(n) for n in range(11)]
#加入筛选
list(map(fac, filter(lambda n: n%2, range(6))))
[fac(n) for n in range(6) if n % 2]

高阶函数

#列表排序
‘’‘
sort 永久  sorted(list, key=reverse) 暂时
[::-1] 逆序 reverse同逆序
‘’‘
from functools import reduce
from operator import add

reduce(add, range(100))
sum(range(100))

创建可调用

import random

class Bin:
    
    def __init__(self, items):
        self._items = list(items)
        random.shuffle(self._items)

    def pick(self):
        try:
            return self._items.pop()
        except IndexError:
            raise LookupError('pick from ')

    def __call__(self):
        return self.pick()

支持函数式编程的包

from functools import reduce
from operator import mul
def fac(n):
    return reduce(lambda a,b: a*b, range(1, n+1))

def fac(n):
    return reduce(mul, range(1, n+1))

functions.partial冻结参数

from operator import mul
from functools import partial

tripe = partial(mul, 3)
tripe(7)