Re: Optimising assignment using std::swap

From: Dean Sturtevant (deansturtevant_at_[hidden])
Date: 2001-01-22 07:21:44

--- In boost_at_[hidden], "Moore, Paul" <paul.moore_at_u...> wrote:
> From: Dean Sturtevant [mailto:deansturtevant_at_m...]
> > I find it hard to imagine a case where std::swap is more 
efficient 
> > than assignment, unless the assignment is coded inefficiently. 
Can 
> > you provide an example where that might not be the case?
> 
> My thought was a long-integer type where the internal 
representation was a
> (potentially) large array of "digits". The swap operation could be 
a simple
> pointer exchange, whereas assignment would need allocation and 
copying of a
> new digit array. (Assuming reference counting isn't used, possibly 
for
> thread-safety reasons).
> 
> It seems fairly likely that this would be the case.
> 
Good example (Evidently my imagination isn't rich enough).
- Dean
> Paul.