How to add property to a class dynamically?

Question

The goal is to create a mock class which behaves like a db resultset.

So for example, if a database query returns, using a dict expression, {\'ab\':100, \'cd\'

Answer 1

The best way to achieve is by defining __slots__. That way your instances can't have new attributes.

ks = ['ab', 'cd']
vs = [12, 34]

class C(dict):
    __slots__ = []
    def __init__(self, ks, vs): self.update(zip(ks, vs))
    def __getattr__(self, key): return self[key]

if __name__ == "__main__":
    c = C(ks, vs)
    print c.ab

That prints 12

    c.ab = 33

That gives: AttributeError: 'C' object has no attribute 'ab'