魔法方法__del

BrightXiong

# !/usr/bin/python3
# -*- coding: utf-8 -*-
# @Time   : 2023/2/15 22:47
# @Author : xiongming
# @File   : magic_func.py
# @Desc   : 魔法方法

# __new__(cls[,...]

class CapStr(str):
    def __new__(cls, string):
        string = string.upper()
        return super().__new__(cls, string)

# 实例创建前进行了拦截，super().__new__()才创建真正的实例
cs = CapStr("FishC")
print(cs)

# __del__(self) 没有引用的实例销毁方法
class C:
    def __init__(self):
        print("我来了")
    def __del__(self):
        print("我走了")

c = C()
del c

class D:
    def __init__(self, name):
        self.name = name
    def __del__(self):
        global x
        x = self

d = D("小甲鱼")
print(d.name)
print(d)
del d
print(x)
print(x.name)

class E:
    def __init__(self, name, func):
        self.name = name
        self.func = func
    def __del__(self):
        self.func(self)

# 闭包实现实例引用删除后，还保留引用对象
def outer():
    x = 0
    def inner(y=None):
        nonlocal x
        if y:
            x = y
        else:
            return x
    return inner


print("----------分隔符-----------")
f = outer()
e = E("小甲鱼", f)
print(e)
print(e.name)
del e
g = f()
print(g)
print(g.name)