为什么在多重继承中只能调用一个类的init方法 [英] Why in Multiple Inheritance only one class init method get called

问题描述

在a.py模块中

class Foo(object):
    def __init__(self):
        self.foo = 20

class Bar(object):
    def __init__(self):
        self.bar = 10

class FooBar(Foo, Bar):
    def __init__(self):
        print "foobar init"
        super(FooBar, self).__init__()
a = FooBar()
print a.foo
print a.bar

在多个继承中，只有一流的init方法被调用. 有什么方法可以在多个继承中调用所有init方法，所以我可以访问所有类实例变量

In multiple inheritances only first class init method getting called. Is there any way to call all init method in multiple inheritances, so I can access all classes instances variable

输出:

foobar init
20
Traceback (most recent call last):
File "a.py", line 16, in <module>
    print a.bar
AttributeError: 'FooBar' object has no attribute 'bar'

无法访问 Bar 类变量栏

推荐答案

class Foo(object):
def __init__(self):
    super(Foo,self).__init__()
    self.foo = 20

class Bar(object):
def __init__(self):
    super(Bar,self).__init__()
    self.bar = 10


class FooBar(Bar,Foo):
def __init__(self):
    print "foobar init"
    super(FooBar,self).__init__()



a = FooBar()
print a.foo
print a.bar

super()调用在每个步骤都以MRO(方法解析顺序)查找/next方法/，这就是为什么Foo和Bar也必须拥有它，否则执行会在Bar的末尾停止.初始化.

The super() call finds the /next method/ in the MRO(method resolution order) at each step, which is why Foo and Bar have to have it too, otherwise execution stops at the end of Bar.init.

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