依赖注入

#!/usr/bin/env python
class Mapper:
    __mapper_relation = {}#__私有化,其他类不能访问

    @staticmethod
    def register(cls,value):
        Mapper.__mapper_relation[cls] = value

    @staticmethod
    def exist(cls):
        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):
        obj = cls.__new__(cls, *args, **kwargs)
        arg_list = list(args)
        if Mapper.exist(cls):
            value = Mapper.value(cls)
            arg_list.append(value)
        obj.__init__(*arg_list,**kwargs)
        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')
a = Foo()
b= Bar()
print(a.name)
print(b.name)

#!/usr/bin/env python
class Mapper:
    __mapper_relation = {}#__私有化,其他类不能访问

    @staticmethod
    def register(cls,value):
        Mapper.__mapper_relation[cls] = value

    @staticmethod
    def exist(cls):
        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):
        obj = cls.__new__(cls, *args, **kwargs)
        arg_list = list(args)
        if Mapper.exist(cls):
            value = Mapper.value(cls)
            arg_list.append(value)
        obj.__init__(*arg_list,**kwargs)
        return obj

class Testt:
    def __init__(self):
        pass

class Foo(metaclass=MyType):

    def __init__(self, f):
        self.f = f

    def f1(self):
        print(self.f)

class Bar(metaclass=MyType):
    def __init__(self, b):
        self.b = b

    def f1(self):
        print(self.b)
Mapper.register(Foo,Testt())
Mapper.register(Bar,Foo())

a = Bar()
print(a.b.f)