Question

I want to use __setattr__ only when the attribute was not found in the object’s attributes, like __getattr__.

Do I really have to use try-except?

def __setattr__(self, name, value):
    try:
        setattr(super(Clazz, self), name, value)
    except AttributeError:
        # implement *my* __setattr__
        pass

Answer 1

You can use hasattr():

def __setattr__(self, name, value):
    if hasattr(super(Clazz, self), name):
        setattr(super(Clazz, self), name, value)
    else:
        # implement *my* __setattr__
        pass