No trees in the stdlib?

[João Valverde]

Paul Rubin wrote:
> João Valverde <backup95 at netcabo.pt> writes:
>   
>> Interesting, thanks. The concept is not difficult to understand but
>> I'm not sure it would be preferable. A copy operation should have the
>> same cost as a "snapshot", 
>>     
>
> You mean a deep-copy?  That is unnecessarily expensive; with a
> functional structure you can snapshot (or copy) by copying a single
> pointer.
>
>   

Shallow copy...

>> undo is kind of redundant and multithreading... don't see a
>> compelling use that would justify it. 
>>     
>
> Here is one:
>  http://groups.google.com/group/comp.lang.python/msg/1fbe66701e4bc65b
>
>   

I just skimmed that but if someone really needs multithreading for such 
intensive processing without wanting a database, fair enough I guess.

>> Have you considered how the syntax would work in Python by the way? This:
>> new_tree = old_tree.insert(object)
>> Just looks wrong. 
>>     
>
> It looks fine to me.  Obviously you could support a wrapper with
> a mutating slot that holds a pointer to the tree.
>   
I didn't get the last part, sorry. But I think you'd have a lot of users 
annoyed that the interface is similar to a list yet their objects 
mysteriously disappear. To me, tree.insert() implies mutability but I 
defer that to others like yourself with more experience in Python than me.