[Python-ideas] add a list.swap() method

[Scott David Daniels]

Jared Grubb wrote:
> 
> On 25 Jun 2009, at 17:41, Steven D'Aprano wrote:
>> What you really want is a fast way of initialising a list, given another
>> list. That was your use-case, after all. Swapping the contents is just
>> one particular implementation of that fast-initialise.
> 
> FWIW, this use case really sounds a lot like rvalue references, a new 
> feature being added to the new C++0x standard. The basic idea is that, 
> for efficiency reasons, you want to be able to "sink" the contents an 
> object and leave the object in a destructable (but not necessarily 
> valid) state.
> 
> This would be a tough (and probably inappropriate?) feature in Python, 
> but I mention it because the concept might provide further 
> context/justifications/trade-offs/ideas for what is being discussed here.

The OP might consider code that does the swap if the refcount is 1,
otherwise does something akin to recur(arg.copy())  (which _will_ have
a refcount of 0).

--Scott David Daniels
Scott.Daniels at Acm.Org