[Tutor] dictionaries, objects and scoping...

[Kent Johnson]

John Morris wrote:
> Ahhh. so namespaces are scoped, not objects...

I would say names are scoped, but I guess namespaces are too.

> You have to keep your objects separate (and make copies when needed), 

Yes

> Python just keeps namespaces (names that refer to an object) scoped 
> according to it's rules:
> http://docs.python.org/ref/naming.html
> 
> So if you create an object way up in terms of scope (global), then all 
> python does is handle what names are available in a given scope to refer 
> to it. If you want a separate object you have to take care of that 
> yourself. Efficient. 

Yes. Assignment is not copying, it is name-binding.

> Massive potential for gotchas, especially with some 
> of python's cleverness in terms of scoping rules.

In my experience it is rare to actually need a copy of an object, and 
usually pretty clear when I do. The real hurdle is getting your mental 
model in sync with what Python is actually doing, rather than what you 
think it should be doing.

Kent