为什么assert不能在抽象类中工作？

Question

我需要你的帮助来理解为什么assert不能在我的代码中工作(我正在使用这段代码来学习抽象类，getters和setters)，我是一个抽象类的新手。

如果我在power属性中设置了一个负数，代码应该停止并显示一个警告，但是assert会忽略power是负数、零还是非负数。

另一个测试代码在基类中没有具体的方法，但在子类中有相同的具体方法代码停止并给我一个警告。

下面是我要测试的完整代码。

from abc import ABC, abstractmethod

class Load(ABC):
    #That's a class to create load to circuits.
    @abstractmethod
    def __init__(self, power=0, power_factor=1):
        self.__power = power
        self.__power_factor = power_factor

    # the attributte name and the method name must be  same
    # which is used to set the value for the attributte
    @property
    def power(self):
        return self.__power

    @power.setter
    def power(self, power):
        # AT TEST SHOULD STOP HERE ANY CONDITION - ONLY TEST PURPOSEs
        # BUT HERE ASSERT IS IGNORED
        assert (power < 0), "power must be non-negative"
        assert (power >= 0), "***power must be negative - ONLY TEST"
        self.__power = power

    @property
    def power_factor(self):
        return self.__power_factor

    @power_factor.setter
    def power_factor(self, power_factor):
        assert 0 < power_factor <= 1, "power factor must be greater 0 until 1"
        self.__power_factor = power_factor


class Specific(Load):
    def __init__(self, power, power_factor):
        super().__init__(power, power_factor)
    # the attributte name and the method name must be  same
    # which is used to set the value for the attributte

### ONLY TESTs PURPOSE

a = Specific(-11,1) # TO FORCE THE ERROR
print(a.power, a.power_factor)
a.power_factor = .4
print(a.power, a.power_factor)

我做错了什么？

Answer 1

你没有使用你的setter -你直接赋值给你的支持字段。

使用

class Load(ABC):
    #That's a class to create load to circuits.
    @abstractmethod
    def __init__(self, power=0, power_factor=1):
        self.power = power                          # acutally use the setter, do not
        self.power_factor = power_factor            # set the backing field directly...

所以你的setter会检查这些值。