Use of templates to avoid redudancy of code

[Fawzi Mohamed]

On 2008-06-03 11:39:24 +0200, Mael <mael.primet at gmail.com> said:

> Hello,
> 
> I'm writing an algorithm that has, say, too possible behaviour 
> depending on a switch. Since there are many imbricated loops, and the 
> behaviour change is inside the loop, testing for the flag is 
> time-consuming

I trust you really profiled the code to see this (never optimize before 
testing)

> for( ....)
> for( .... )
> for( ... )
> {
>   if( flag ) action_1 ;
>   else action_2 ;
> }
> 
> is there a clean way to use templates to generate the duplicate of the 
> code like
> 
> if( flag )
> {
>   for(...) .... action1 ;
> }
> else
> {
>   for(...) .... action2 ;
> }

a simple compile time solution is to make the looping construct a 
template, and the action a template parameter (either alias or char[] 
to mixin if you need).

I used it extensively in my multidimensional array lib...