内置方法介绍

# --------- isinstance ------------
class Foo:
    pass

obj = Foo()

print(isinstance(obj,Foo)) # 结果为True

# ---------- issubclass ------------

class Foo:
    pass


class Bar(Foo):
    pass

print(issubclass(Bar,Foo)) # 结果为True

# 内置方法 Item 系列


class Foo:
    def __init__(self, name):
        self.name = name

    def __getitem__(self, item):
       return self.__dict__.get(item)

    def __setitem__(self, key, value):
        self.__dict__[key] = value

    def __delitem__(self, key):
        del self.__dict__[key]


obj = Foo('kingforn')
print(obj.name)         # 执行结果：kingforn
print(obj['name'])      # 执行结果：kingforn

obj['sex'] = 'female'
print(obj.__dict__)     # {'name': 'kingforn', 'sex': 'female'}

del obj['sex']
print(obj.__dict__)     # {'name': 'kingforn'}

# __str__ 方法
d = dict({'name':'kingforn','age':18})
print(isinstance(d,dict))               # 执行结果为 True
print(d)                                # 执行结果为 {'name': 'kingforn', 'age': 18}

class Foo:
    pass

d1 = Foo()
print(isinstance(d1,Foo))               # 执行结果为 True
print(d1)                               # 执行结果为 <__main__.Foo object at 0x00000206C52C4C18>

class People:
    def __init__(self,name,age):
        self.name=name
        self.age=age

    def __str__(self):
        return '<name : %s , age : %s>' % (self.name, self.age)


d2 = People('alex', 18)
print(d2)                               # 执行结果为 <name : alex , age : 18>

__del__ 方法

class Open:
    def __init__(self,filename):
        print('open file ...............')
        self.filename=filename

    def __del__(self):
        print('自动回收操作系统资源：self.close()')

f = Open('settings.py')
print('----- main ----------')
'''
执行结果为：
    open file ...............
    ----- main ----------
    自动回收操作系统资源：self.close()
'''