Python入门学习笔记9：Python高级语法与用法-枚举、函数式编程<闭包>

#Python高级语法与用法
#枚举
from enum import Enum, IntEnum,unique


class VIP(Enum):
    YELLOW = 1
    GREEN = 2
    BLACK = 3
    RED = 4

class VIP1(Enum):
    YELLOW = 1
    YELLOW_ALIAS = 1#别名
    GREEN = 2
    BLACK = 3
    RED = 4

@unique#装饰器：作用为鉴别若常量有相同时会进行报错处理
class VIP2(IntEnum):#整数型限制
    YELLOW = 1
    GREEN = 2
    BLACK = 3
    RED = 4


print("name:",VIP.YELLOW.name,",value:",VIP.YELLOW.value)
#变量
yellow = 1
green = 2
#字典
{'yellow':1,'green':2}
#类下的类变量


class TypeDiamond():
    yellow = 1
    green = 2

"""
枚举的特点：
常量（不可变）、防止相同值的功能
枚举中的变量名称不能重复
常量相同，变量不同时
枚举类型无法实例化的
设计模式（23中设计模式）：单例模式
"""
print(VIP1.YELLOW)
print(type(VIP.GREEN.name))#<class 'str'>
print(type(VIP.GREEN))#<enum 'VIP'>
print(VIP['GREEN'])#VIP.GREEN

for vip in VIP:
    print(vip)
for vip1 in VIP1.__members__.values():#遍历时包含别名
    print(vip1)
    print(vip1.value)

result = VIP.GREEN == VIP1.GREEN
result1 = VIP.GREEN is VIP.GREEN
print(result,result1)#False True


a = 1
print(VIP(a))#VIP.YELLOW
if VIP(a) == VIP.YELLOW:
    print("VIP YELLOW")
if VIP(a) == VIP.BLACK:
    print("VIP BLACK")#VIP YELLOW

#函数式编程

#Python一切皆对象
#闭包 = 函数+环境变量(函数定义的时候)


def curve_pre():
    a1 = 25

    def curve(x):
        return a1*x*x
    return curve

a2 = 10
f = curve_pre()
f(2)#等价于curve(2)
print(type(f),f(2),f.__closure__,f.__closure__[0].cell_contents)#<class 'function'> 100 (<cell at 0x10488a790: int object at 0x10455cda0>,) 25

a3 = 10


def f3(x):
    return a3 * x * x


print(f3(2))

#闭包的事例


def f1():
    a4 = 10#此处为该闭包的环境变量

    def f2():
        #a = 20   #a此处将被Python认为是一个局部变量(无法调用外部环境变量导致无法形成闭包，所以此时不能将a进行赋值)
        #print(a)
        return a4
    #print(a)#第一步
    #f2()#第二步
    #print(a)#第三步
    return f2


f1 = f1()
print('f1:',f1,',f.__closure__:',f1.__closure__)


origin = 0


def go(step):
    global origin #global关键字定义全局变量且记录并累加
    new_pos = origin +step
    origin = new_pos
    return origin


print(go(2))
print(go(3))
print(go(6))

origin1 = 0


def factory(pos):
    def go1(step):
        nonlocal pos#不是本地的全局变量
        new_pos = pos + step
        pos = new_pos
        return new_pos
    return go1


tourist = factory(origin1)
print(tourist(2))
print(tourist.__closure__[0].cell_contents)
print(tourist(3))
print(tourist.__closure__[0].cell_contents)
print(tourist(6))
print(tourist.__closure__[0].cell_contents)