Possible Error in this course : Add behavior with methods / Introduction to object-oriented programming with Python

Question

class Square:

    def __init__(self, w, h):
        self.__height = h
        self.__width = w

    def set_side(self, new_side):
        self.__height = new_side
        self.__width = new_side

    @property
    def height(self):
        return self.__height

    @height.setter
    def height(self, new_value):
        if new_value >= 0:
            self.__height = new_value
        else:
            raise Exception("Value must be larger than 0")

In the preceding code, the function height() is decorated by the decorator @property. This decoration action creates the private field __height. The __height field isn't defined in the constructor __init__() because the decorator does that already. There's also another decoration happening, namely, @height.setter. This decoration points out a similar-looking height() method as the setter. The new height method takes on another parameter value as its second parameter.

The __height field isn't defined in the constructor __init__() because the decorator does that already.

The quoted statement mentions __height is not defined in the constructor, but it actually is. What is the correct understanding?

This question is related to the following Learning Module

Answer 1

The quoted statement is incorrect. The __height field is indeed defined in the constructor __init__(), where it is initialized with the value of the parameter h. The @property decorator does not define the field; instead, it provides a way to access the private attribute __height through a public interface. The @height.setter decorator allows you to set the value of __height while enforcing any conditions specified in the setter method.

In summary, the correct understanding is that the __height field is explicitly defined in the constructor, and the decorators are used to manage access to this private field.

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References:

• Using Properties (C# Programming Guide)
• Classes and methods