swap (a, b) suggestion

[Gabriel Dos Reis]

>>>>> «Eric», Eric Buddington <eric@sparrow.vgernet.net> wrote:

Eric> Greetings.
Eric> I am just learning about STL, and have found a possible improvement
Eric> for the swap() template in include/g++/stl_algobase.h.  The template
Eric> here is straightforward:

Eric> template <class T>
Eric> inline void swap(T& a, T& b) {
Eric>   T tmp = a;
Eric>   a = b;
Eric>   b = tmp;
Eric> }

Eric> For integer values, the following works, and is significantly faster:

Eric> template <class T>
Eric> inline void swap(T& a, T& b) {
Eric>   a ^= b;
Eric>   b ^= a;
Eric>   a ^= b;
Eric> }

	This works fine for integral types. But about float/double and
more generaly non-integral types (complex<>, ...)


Eric> In my own code, this change sped up a quicksort significantly.
Eric> Explicit versions for char, short, int, and long (and their unsigned
Eric> counterparts) alongside the template would do the trick.

Eric> I'll be interested to hear any comments. Thanks for your collective
Eric> work - egcs has really saved my butt development-wise.

	specialisations for the template function swap<>() for
integral types may be added. Uli ?

-- Gaby