Bracket assignment in Python

Question

I would like to create a class that is able to do the following

class Test:
    # code here

test = Test()
test["test"] = 1
test.test  # returns 1

Is this possible in Python using magic methods (e.g. not inheriting from dict)?

Answer 1

You could override __getitem__ and __setitem__ using getattr and setattr:

class Test:
    def __getitem__(self, key):
        return getattr(self, key)

    def __setitem__(self, key, value):
        setattr(self, key, value)


test = Test()
test["test1"] = 1
print(test.test1)

Using this method, you can also set from the attribute and get from the square bracket operator:

test = Test()
test.test2 = 2
print(test["test2"])

If you wanted to use this among many classes then you could turn this into a base class:

class ItemAttributes:
    def __getitem__(self, key):
        return getattr(self, key)

    def __setitem__(self, key, value):
        setattr(self, key, value)


class Test(ItemAttributes):
    pass