does Python support some kind of "casting"

[Tino Lange]

Duncan Booth wrote:

Hi Duncan!

Thanks for your answer!

>> So the best solution is to transport an object like
>> return list(newlist)
>> 
>> But I guess this makes a temporary copy of my MaxSizedList just for the
>> XML-RPC-transport, or? So it's horrible inefficient?
>> 
> Yes, that will make a copy. But copying a list is a pretty efficient
> operation, so no, it isn't really horribly inefficient. Have you tried it
> and identified this as a bottleneck? How long are your lists anyway?

3600 Elements each.

No I didn't check if it's a bottleneck. But I immediately didn't feel good 
when writing "return list(newlist)"
(the list contains a list of strings itself - so it's much stuff to copy)

> One way to do this that avoids the copying is to aggregate a list object
> into your class instead of trying to subclass the list type. Then you can
> simply return the internal list object if you want.

I think I'll do that.
Funny: This is the userlist-approach - so despite having the new 2.2 
feature of subclassing it's better to use the old userlist.
 
> However, from your description I would be much more worried about the
> throwing away elements from the front of the list every time you append to
> the end of the list. I do hope you are batching these up into large chunks
> to be discarded, not throwing them away one or two at a time.

Of course :-)
This logic took most of the implementation time.
But I can just copy it in the userlist MaxSizedList - that's no problem.

Thanks!
Best regards

Tino