I working with Octahedral Faces both in 2D and 3D. There's a matrix which rotates one to the other, but both of them have methods and properties which are unique to either representation. I was thinking of using an ABC, and then Face2D/Face3D as subclasses - but I'm not sure that's the right approach. Instead of an ABC, how about a decorator class of some sort that implements as_2D/as_3D methods - which keeps either/both as they are required? Up until now I have been using a general Face class, but it's getting unwieldy. This is why I am thinking of subclassing. I'm suggesting something like the following class Face: def __init__(self, name, vertices): self.name = name self.vertices = vertices self._2d = None self._3d = None def to_3d(self): """ 3D instantiation """ raise NotImplementedError def to_2d(self): """ 2D instantiation """ raise NotImplementedError def as_3d(self): if self._3d is None: self._3d = self.to_2d() return self._3d def as_2d(self): if self._3d is None: self._3d = self.to_2d() return self._2d class Face3D(Face): def __init__(self, name, vertices): super().__init__(name, vertices) self._3d = self class Face2D(Face): def __init__(self, name, vertices): super().__init__(name, vertices) self._2d = self I am wary of this though - it sort of feels like I am doing some sort of weird inheritance hierarchy trick which could be better dealt with via composition instead of inheritance. I am not looking for an opinion. I am asking for a clear explanation of how to approach this sort of issue from an OO standpoint. The question is about how to identify suitable class relations. Continue reading...
