Doubt on the Setter

Question

class Bola:

    def __init__(self, cor, circunferencia, material):
        self.__cor = cor
        self.__circunferencia = circunferencia
        self.__material = material

    @cor.setter
    def cor(self, cor):
        self.__cor = cor

    @property 
    def mostraCor(self):
        return self.__cor  

Guys, I’m doing this exercise on Jupyter Notebook, but it’s making the following mistake:

      NameError                                 Traceback (most recent call last)
  <ipython-input-12-c66d63af7d4c> in <module>
  ----> 1 class Bola:
        2 
        3     def __init__(self, cor, circunferencia, material):
        4         self.__cor = cor
        5         self.__circunferencia = circunferencia

  <ipython-input-12-c66d63af7d4c> in Bola()
        6         self.__material = material
        7 
  ----> 8     @cor.setter
        9     def cor(self, cor):
       10         self.__cor = cor

  NameError: name 'cor' is not defined

Could someone help me? The problem is in Setter, but I don’t know how to fix it.

Answer 1

When you use the idea of Property you can start from two different approaches:

1. Use class Property as follows:

algum_atributo = property(fget=None, fset=None, fdel=None, doc=None)

Where Property will return an object that will handle the get, set, and del that have been passed as arguments to the various access forms of your "some attribute", ie, every time you want, for example make a get from the attribute, the object will call the function you passed as the fget and so on.

2. Using the @Property decorator, which works with the same function above, the difference is that under the function that will perform the get in your attribute you will decorate it with the @Property, for example:

@property
def algum_atributo(self):
    return self._algumatributo

That is, every time you perform the following command:

SeuObjeto.algum_atributo

You will call the method decorated by @Property. The important point that needs to be remembered is that, to define the Setter it must be done as follows:

@nome_funcao_decorada.setter
def nome_funcao_decorada(self,value):
    self._algumatributo = value

Where in that case, for what we did, it would be translated like this:

@algum_atributo.setter
def algum_atributo(self,value):
    self._algumatributo = value

In short, you need to use the same name as the function decorated by @Property in the Tter decorator, and even more, to facilitate use and understanding, it is recommended that the same names be used for the decorated functions.

I hope I’ve helped.