[Tutor] setattr vs __setattr__

[Steven D'Aprano]

On Mon, 6 Sep 2010 09:03:30 pm Rasjid Wilcox wrote:
> I've been using
>
> for attr_name in name_list:
>     setattr(a, attr_name, getattr(b, attr_name))
>
> to copy the attributes from one type of class to another, and it is
> not quite as readable as I would like.

The one-liner in the for loop is very concise. The problem is that 
concise is often the opposite of readable. So make it less concise:


for name in name_list:
    obj = getattr(b, name)
    setattr(a, name, obj)

Does that help?

Another alternative, depending on the class, *might* be this:

a.__dict__.update(b.__dict__)

although that's a hack, and like all hacks, may not do what you expect 
for all classes.


> Actually, I've just thought 
> that the best option would be to make both classes dictionary like
> objects with automatic translation between a['foo'] and a.foo.

How does that help you copy from one class to another? As I see it, it 
just adds more noise to the class.


-- 
Steven D'Aprano