[Python3 填坑] 018 组装类的几个例子

2024-09-03 23:23:54

目录

1. print( 坑的信息 )
2. 开始填坑

1. print( 坑的信息 )

挖坑时间：2019/04/07
明细

坑的编码	内容
Py024-2	MethodType 举例
Py024-3	type 举例
Py024-4	MetaClass 举例

2. 开始填坑

2.1 MetaClass 举例

from types import MethodType

class A():

    pass

def say(self):

    print("this is say()")

a = A()

a.say = MethodType(say, A)

a.say()

>>>

this is say()

2.2 type 举例

# 1. 定义类应该具有的成员函数

def say(self):

    print("this is say()")

def eat(self):

    print("this is eat()")

# 2. 用 type 来创建一个类

A = type( "AName", (object, ), {"class_say":say, "class_eat":eat})

# 3. 像正常访问一样使用类

a = A()

a.class_say()

a.class_eat()

>>>

this is say()

this is eat()

2.3 MetaClass 举例

# 元类写法是固定的，必须继承自 type

# 元类一般命名以 MetaClass 结尾

class ExampleMetaClass(type):

    def __new__(cls, region, gender, attrs):

        print("this is MetaClass")

        attrs['id_num'] = '9527'

        attrs['age'] = "18"

        return type.__new__(cls, region, gender, attrs)

# 元类定义完就可以使用

class Person(object, metaclass=ExampleMetaClass):

    pass

york = Person()

print(york.id_num)

>>>

this is MetaClass

9527

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