Equivalent of NotImplementedError for fields in Python

Solution 1:

Yes, you can. Use the @property decorator. For instance, if you have a field called "example" then can't you do something like this:

class Base(object):

    @property
    def example(self):
        raise NotImplementedError("Subclasses should implement this!")

Running the following produces a NotImplementedError just like you want.

b = Base()
print b.example

Solution 2:

Alternate answer:

@property
def NotImplementedField(self):
    raise NotImplementedError

class a(object):
    x = NotImplementedField

class b(a):
    # x = 5
    pass

b().x
a().x

This is like Evan's, but concise and cheap--you'll only get a single instance of NotImplementedField.