类，字典，自我，初始化，参数? [英] class, dict, self, init, args?

问题描述

class attrdict(dict):
    def __init__(self, *args, **kwargs):
        dict.__init__(self, *args, **kwargs)
        self.__dict__ = self

a = attrdict(x=1, y=2)
print a.x, a.y

b = attrdict()
b.x, b.y  = 1, 2
print b.x, b.y

有人可以用文字解释前四行吗?我阅读了类和方法.但这里似乎很混乱.

Could somebody explain the first four lines in words? I read about classes and methods. But here it seems very confusing.

推荐答案

您没有在示例中使用位置参数.所以相关代码是:

You are not using positional arguments in your example. So the relevant code is:

class attrdict(dict):
    def __init__(self, **kwargs):
        dict.__init__(self, **kwargs)
        self.__dict__ = self

在第一行中，您将 attrdict 类定义为 dict 的子类.在第二行中，您定义了将自动初始化您的实例的函数.您将关键字参数 (**kargs) 传递给此函数.当你实例化 a 时:

In the first line you define class attrdict as a subclass of dict. In the second line you define the function that automatically will initialize your instance. You pass keyword arguments (**kargs) to this function. When you instantiate a:

 a = attrdict(x=1, y=2)

你实际上是在打电话

attrdict.__init__(a, {'x':1, 'y':2})

dict 实例核心初始化是通过初始化 dict 内置超类来完成的.这是在传递 attrdict.__init__ 中接收到的参数的第三行中完成的.因此，

dict instance core initialization is done by initializing the dict builtin superclass. This is done in the third line passing the parameters received in attrdict.__init__. Thus,

dict.__init__(self,{'x':1, 'y':2})

使self(实例a)成为字典:

self ==  {'x':1, 'y':2}

好东西出现在最后一行:每个实例都有一个保存其属性的字典.这是self.__dict__(即a.__dict__).

The nice thing occurs in the last line: Each instance has a dictionary holding its attributes. This is self.__dict__ (i.e. a.__dict__).

例如，如果

a.__dict__ = {'x':1, 'y':2} 

我们可以编写 a.x 或 a.y 并分别获得值 1 或 2.

we could write a.x or a.y and get values 1 or 2, respectively.

所以，这就是第 4 行所做的:

So, this is what line 4 does:

self.__dict__ = self

相当于:

a.__dict__ = a  where a = {'x':1, 'y':2}

然后我可以调用 a.x 和 a.y.

Then I can call a.x and a.y.

希望不要太乱.

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