Python - extending properties like you'd extend a function

Question

Question

How can you extend a python property?

A subclass can extend a super class\'s function by calling it in the overloaded version, a

Answer 1

You should be calling the superclass properties, not bypassing them via self._dataframe. Here's a generic example:

class A(object):

    def __init__(self):
        self.__prop = None

    @property
    def prop(self):
        return self.__prop

    @prop.setter
    def prop(self, value):
        self.__prop = value

class B(A):

    def __init__(self):
        super(B, self).__init__()

    @property
    def prop(self):
        value = A.prop.fget(self)
        value['extra'] = 'stuff'
        return value

    @prop.setter
    def prop(self, value):
        A.prop.fset(self, value)

And using it:

b = B()
b.prop = dict((('a', 1), ('b', 2)))
print(b.prop)

Outputs:

{'a': 1, 'b': 2, 'extra': 'stuff'}

I would generally recommend placing side-effects in setters instead of getters, like this:

class A(object):

    def __init__(self):
        self.__prop = None

    @property
    def prop(self):
        return self.__prop

    @prop.setter
    def prop(self, value):
        self.__prop = value

class B(A):

    def __init__(self):
        super(B, self).__init__()

    @property
    def prop(self):
        return A.prop.fget(self)

    @prop.setter
    def prop(self, value):
        value['extra'] = 'stuff'
        A.prop.fset(self, value)

Having costly operations within a getter is also generally to be avoided (such as your parse method).