Question

Let’s say I have the following class

class Parent(object):
    Options = {
        'option1': 'value1',
        'option2': 'value2'
    }

And a subclass called Child

class Child(Parent):
   Options = Parent.Options.copy()
   Options.update({
        'option2': 'value2',
        'option3': 'value3'
   })

I want to be able to override or add options in the child class. The solution I’m using works. But I’m sure there is a better way of doing it.

---

EDIT

I don’t want to add options as class attributes because I have other class attributes that aren’t options and I prefer to keep all options in one place. This is just a simple example, the actual code is more complicated than that.

Answer 1

One way would be to use keyword arguments to dict to specify additional keys:

Parent.options = dict(
    option1='value1',
    option2='value2',
)

Child.options = dict(Parent.options,
    option2='value2a',
    option3='value3',
)

If you want to get fancier, then using the descriptor protocol you can create a proxy object that will encapsulate the lookup. (just walk the owner.__mro__ from the owner attribute to the __get__(self, instance, owner) method). Or even fancier, crossing into the probably-not-a-good-idea territory, metaclasses/class decorators.