property decorator and inheritance

[alex23]

On Nov 11, 2:03 pm, Laurent <laurent.pa... at gmail.com> wrote:
> Hi. I couldn't find a way to overwrite a property declared using a decorator in a parent class.

> class Polite:
>     @property
>     def greeting2(self, suffix=", my dear."):
>         return self._greeting + suffix

Here you set up greeting2 as a property.

> class Rude(Polite):
>     @property
>     def greeting2(self):
>         return super().greeting2(suffix=", stupid.")

Here you call Polite.greeting2 as a function.

> print("r.greeting2 =", r.greeting2) # TypeError: 'str' object is not callable

And here it's telling you that you're trying to treat a string - the
output of Polite.greeting2 - as a function.

The problem isn't that you cannot override greeting2 on Rude, it's
that you can't treat properties as functions, so you can't pass in a
new suffix. Instead, break the suffix out as a class attribute, then
each descendent just needs to override that attribute:

  class Polite(object):
    suffix = ', my dear'

    @property
    def greeting(self):
      return 'Hello' + self.suffix

  class Rude(Polite):
    suffix = ', stupid'