python 对象可以有嵌套的属性吗? [英] Can python objects have nested properties?

问题描述

我有一个对象定义如下

class a():@财产定义道具(自我):打印(来自object.prop的你好")@财产def prop1(self):print("你好来自 object.prop.prop")

当我打电话

<预><代码>>>>obj = a()>>>对象道具来自 object.prop 的问候>>>obj.prop.prop

我收到以下回溯错误

回溯(最近一次调用最后一次):文件object_property.py"，第 13 行，在 <module> 中.a.prop.prop1AttributeError: 'NoneType' 对象没有属性 'prop1'

我想弄清楚是否可以为对象定义嵌套属性?

解决方案

回溯是因为你的属性没有 return 语句，因此它返回 NoneType，这显然不能有自己的属性.您的属性可能需要返回不同类的实例，该类具有自己的 prop 属性.像这样:

class a():def __init__(self):self.b = b()@财产定义道具(自我):打印(来自object.prop的你好")回归自我.bb类():@财产定义道具(自我):print("你好来自 object.prop.prop")x = a()打印 x.prop.prop>>来自 object.prop 的问候>>你好来自 object.prop.prop>>没有任何

I have an object defined as follows

class a():
    @property
    def prop(self):
        print("hello from object.prop")
        @property
        def prop1(self):
            print("Hello from object.prop.prop")

When I call

>>> obj = a()
>>> obj.prop
hello from object.prop
>>> obj.prop.prop

I get the following traceback error

Traceback (most recent call last):
  File "object_property.py", line 13, in <module>
    a.prop.prop1
AttributeError: 'NoneType' object has no attribute 'prop1'

What I am trying to figure out is if I can define nested properties for objects?

解决方案

The traceback is because your property doesn't have a return statement, hence it returns NoneType, which obviously can't have attributes of its own. Your property would probably need to return an instance of a different class, that has its own prop attribute. Something like this:

class a():
    def __init__(self):
        self.b = b()
    @property
    def prop(self):
        print("hello from object.prop")
        return self.b

class b():
    @property
    def prop(self):
        print("Hello from object.prop.prop")

x = a()
print x.prop.prop
>> hello from object.prop
>> Hello from object.prop.prop
>> None

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