Python闭包

闭包 = 环境变量 + 函数

调用闭包内部的环境变量

def curve_pre():
    b = 10
    c = 106
    def curve(x):
        return b*c*x*x
    return curve

f = curve_pre()
print(f.__closure__)
print(f.__closure__[0].cell_contents)
print(f(1))
# (<cell at 0x00FDF950: int object at 0x591E4720>, <cell at 0x00FDF9B0: int object at 0x591E4D20>)
# 10
# 1060

闭包的经典误区

def curve_pre():
    a = 10

    def curve(x):
        # a被python认为是环境变量,所以构不成闭包
        a = 20
    return curve


f = curve_pre()
print(f.__closure__)                 # None

闭包与非闭包实现人类走路

1. 非闭包

a = 0

# global引用全局变量
def go(value):
    global a
    newtext = a + value
    a = newtext
    return newtext

print(go1(1))
print(go1(2))
print(go1(3))          # 1 3 6

2. 闭包

oragin = 0

def factory(args):
    def go(post):
        nonlocal args
        newPost = post+ args
        args = newPost
        return args
    return go

f = factory(oragin)

print(f(1))
print(f(2))
print(f(3))