Re: [boost] Re: Optimising assignment using std::swap

From: Jeremy Siek (jsiek_at_[hidden])
Date: 2001-01-23 18:00:52

This situation is like when you're sitting in your car, stopped in front
of a broken stop-light stuck on red. Carefully look both ways, and then
run the red light!

I think the best short-term solution is to use std::abs and std::swap tell
people to define abs(), swap(), etc. functions for their types in
namespace std.

I think we need to make a decision about this soon because it affects many
many things.

I think the best long term solution is to change the standard to make this
legal.

On Tue, 23 Jan 2001, Paul Moore wrote:
gustav> 
gustav> Paul.
gustav> 
gustav> PS In case people think I'm just being petluant, I should point out 
gustav> that without Koenig lookup, the swap() and abs() stuff simply 
gustav> doesn't work. With abs(), you get compile errors, and with swap() 
gustav> you get the wrong version being used (resulting in at best no 
gustav> improvement, and at worst a severe pessimization of the code). I'd 
gustav> rather leave it out than have broken code. And as I've said before, I 
gustav> have to use MSVC, so I won't implement something which doesn't 
gustav> work on that compiler.
gustav> 
gustav> PPS Is it only me who feels that the "using std::swap" incantation 
gustav> required to be able to use swap() unqualified and hence to get the 
gustav> benefit of Koenig lookup is clumsy, unintuitive and inelegant?
gustav> 
gustav> 
gustav> 
gustav> 

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 Jeremy Siek                        www: http://www.lsc.nd.edu/~jsiek/
 Ph.D. Candidate                  email: jsiek_at_[hidden]
 Univ. of Notre Dame         work phone: [phone]
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