子类属性不同的名称

Question

我想要一个子类的属性具有不同于它的父类的相同属性的名称，即使它意味着同样的事情。例如，父类是具有属性“高度”的Shape和具有类似属性“直径”的子类Circle。下面简单介绍一下我现在拥有的内容，但我希望Circle类使用“直径”而不是“高度”。处理这个问题的最好方法是什么？

注意：我将从Circle继承另一个类，该类还需要使用“直径”而不是“高度”。谢谢！

class Shape(): 
    def __init__(self, shape, bar_args, height): 
     self.shape = shape 
     self.height = height 
     etc. 

class Circle(Shape): 
    def __init__(self, height, foo_args, shape='circle'): 
    Shape.__init__(self, shape, height) 
     self.height = height 
     etc. 

Answer 1

你可以定义一个property它访问的读写访问原始属性：

class Circle(Shape): 
    def __init__(self, height, foo_args, shape='circle'): 
     Shape.__init__(self, shape, height) # assigns the attributes there 
     # other assignments 
    @property 
    def diameter(self): 
     """The diameter property maps everything to the height attribute.""" 
     return self.height 
    @diameter.setter 
    def diameter(self, new_value): 
     self.height = new_value 
    # deleter is not needed, as we don't want to delete this. 

如果你想这种行为非常频繁，你找物业与二传手处理和getter太不方便，你可以去迈高和build自己descriptor class：

class AttrMap(object): 
    def __init__(self, name): 
     self.name = name 
    def __get__(self, obj, typ): 
     # Read access to obj's attribute. 
     if obj is None: 
      # access to class -> return descriptor object. 
      return self 
     return getattr(obj, self.name) 
    def __set__(self, obj, value): 
     return setattr(obj, self.name, value) 
    def __delete__(self, obj): 
     return delattr(obj, self.name) 

有了这个，你可以再做

class Circle(Shape): 
    diameter = AttrMap('height') 
    def __init__(self, height, foo_args, shape='circle'): 
     Shape.__init__(self, shape, height) # assigns the attributes there 
     # other assignments 

和diameter描述将重定向所有访问它命名的属性（这里：height）。