May 30, 2018

工具, Python

由于python 没有抽象类、接口的概念，所以要实现这种功能得abc.py 这个类库,具体方式如下

import abc
class Foo(metaclass=abc.ABCMeta):  ##抽象类
    def f1(self):
        print(123)
 
    def f2(self):
        print(456)
 
    @abc.abstractmethod  ##抽象方法
    def f3(self):
        '''
        ???
        :return:
        '''
 
class Bar(Foo):
    def f3(self):
        print(33333)
 
b = Bar()
b.f3()

依赖注入实现

引入依赖注入

解释器解释类的流程

# ======================================解释器解释类的流程===================
#  解释器解释：
# class Foo:
#     def __init__(self):
#         self.name =123
#     def f1(self):
#         print(self.name)
# 1.遇到class Foo,执行type的__init__方法
# 2.type的init的方法做什么呢！不知道
# obj =Foo()
# obj.f1()
# 3.执行Type的__call__方法
# 执行Foo类的__new__方法
# 执行Foo类的__init__方法

依赖注入在什么之前做什么操作

class MyType(type):
    def __call__(cls, *args, **kwargs):  ##执行Type的__call__方法，这里的cls就是<__main__.Foo object at 0x001B59F0> Foo类
        obj = cls.__new__(cls, *args, **kwargs)  ##Foo的__new__方法
        print('-------------')
        obj.__init__(*args, **kwargs)  ##在执行Foo的__init__的之前做什么操作
        return obj
 
 
class Foo(metaclass=MyType):
    def __init__(self, name):
        print('============')
        self.name = name
 
    def f1(self):
        print(self.name)
 
 
obj = Foo(123)
print(obj)
print(obj.name)

#=================================依赖注入案例一======================================
class MyType(type):
    def __call__(cls, *args, **kwargs):  ##执行Type的__call__方法，这里的cls就是<__main__.Foo object at 0x001B59F0> Foo类
        obj = cls.__new__(cls, *args, **kwargs)  ##Foo的__new__方法
        if cls == Foo1:
            obj.__init__(Foo())
        elif cls == Foo2:
            obj.__init__(Foo1())
        return obj
 
 
class Foo(metaclass=MyType):
    def __init__(self, args):
        print('============')
        self.name = args
 
    def f(self):
        print(self.name)
 
class Foo1(metaclass=MyType):
    def __init__(self, args):
        print('============')
        self.name = args
 
    def f1(self):
        print(self.name)
 
class Foo2(metaclass=MyType):
    def __init__(self, args):
        print('============')
        self.name = args
 
    def f2(self):
        print(self.name)
 
 
obj = Foo2()
obj.f2()
# <__main__.Foo1 object at 0x002DA4F0>

#######################依赖注入案例二====================================================
 
#
# class Mapper:
#     __mapper_relation = {}
#
#     @staticmethod
#     def register(cls, value):
#         Mapper.__mapper_relation[cls] = value
#
#     @staticmethod
#     def exist(cls):   ###判断是否在里面
#         if cls in Mapper.__mapper_relation:
#             return True
#         return False
#
#     @staticmethod
#     def value(cls):
#         return Mapper.__mapper_relation[cls]
#
#
# class MyType(type):
#     def __call__(cls, *args, **kwargs):  ##执行Type的__call__方法，这里的cls就是<__main__.Foo object at 0x001B59F0> Foo类
#         obj = cls.__new__(cls, *args, **kwargs)  ##Foo的__new__方法
#         arg_list = list(args)
#         if Mapper.exist(cls):
#             value = Mapper.value(cls)
#             arg_list.append(value)
#         obj.__init__(*arg_list, **kwargs)  ##在执行Foo的__init__的之前做什么操作
#         return obj
#
#
# class Foo(metaclass=MyType):
#     def __init__(self, name):
#         self.name = name
#
#     def f1(self):
#         print(self.name)
#
#
# class Bar(metaclass=MyType):
#     def __init__(self, name):
#         self.name = name
#
#     def f1(self):
#         print(self.name)
#
#
# Mapper.register(Foo, '666')
# Mapper.register(Bar, '999')
# obj = Foo()
#
# print(obj)
# print(obj.name)
# b = Bar()
# print(b.name)
 
# <__main__.Foo object at 0x00583810>
# 666
# 999

• Python标准库