抽象类中的过载

Question

我试图弄清楚如何将__添加__方法在python中作为抽象类，但无法。这是我要解决的问题：

import numpy as np 
from abc import ABC, abstractmethod

class RandomVariable(ABC):
    @abstractmethod
    def sample(self):
        pass
    
    # I want to override the __add__ method 
    # to return a random variable
    # such that the sample method is the addition from 
    # left.sample() and right.sample()
    
class NormalVariable(RandomVariable):
    def __init__(self, mu=0, sigma=1):
        self.mu = mu
        self.sigma = sigma
    def sample(self):
        return np.random.normal(self.mu, self.sigma)

class ExponentialVariable(RandomVariable):
    def __init__(self, scale=1):
        self.scale=scale
    def sample(self):
        return np.random.exponential(self.scale)

也就是说，我希望能够执行my_random_variable = normalVariable（） + exponentialVariable（）。

编辑

这是解决它的标准方法：

import numpy as np 
from abc import ABC, abstractmethod



class RandomVariable(ABC):
    @abstractmethod
    def sample(self):
        pass
    
    def __add__(self, other):
        return AddedVariable(left=self, right=other)
    
    
class NormalVariable(RandomVariable):
    def __init__(self, mu=0, sigma=1):
        self.mu = mu
        self.sigma = sigma
    def sample(self):
        return np.random.normal(self.mu, self.sigma)

class ExponentialVariable(RandomVariable):
    def __init__(self, scale=1):
        self.scale=scale
    def sample(self):
        return np.random.exponential(self.scale)
    
    
class AddedVariable(RandomVariable):
    def __init__(self, left, right):
        self.left = left 
        self.right = right
    def sample(self):
        return self.left.sample() + self.right.sample()