Re: [Boost-users] [preprocessor] ADD efficiency / documentation?

From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2008-08-08 22:02:46

AMDG

Isaac Dupree wrote:
> This documentation is self-contradictory:
>
> http://www.boost.org/doc/libs/1_35_0/libs/preprocessor/doc/ref/add.html
>
> "This macro is the most efficient when x is less than or equal to y.  
> However, the efficiency gain is not worth actually comparing the two 
> arguments prior to invocation. In other words, x should be the addend 
> that is most likely to be the largest of the two operands."
>
> The first sentence says we want (x <= y); the last sentence says we 
> want (x > y).  Which is it? :-)

The algorithm is

while(y) {
    ++x;
    --y;
}

So the latter is correct.

In Christ,
Steven Watanabe