foreach(r; requests) { r.concider(); }

[Steven Schveighoffer]

On Fri, 04 Nov 2011 09:01:11 -0400, Christophe  
<travert at phare.normalesup.org> wrote:

> "Steven Schveighoffer" , dans le message (digitalmars.D:146563), a
>  écrit :
>
> The foreach delegate syntax already allow you to have parametrized
> iteration over a structure !
>
> Actually, the delegate do not have to be returned by the & operator, it
> can be returned by a function. It's a bit awkward first, but then it's
> easy to use:
>
> struct Iterable
> {
>     int delegate(int delegate(ref int)) inReverse()
>     {
> 	return ()
> 	{
>           int result = 0;
>           foreach(int i; 0..100)
>           {
>              auto t = 99-i;
>              if((result = dg(t)) != 0) break;
>           }
>           return result;
> 	}
>     }
>
>     int delegate(int delegate(ref int)) byStep(int step)
>     {
>        return()
>          {
>            int result = 0;
>            foreach(int i; iota(0, 100, step))
>            {
>               auto t = i;
>               if((result = dg(t)) != 0) break;
>            }
>            return result;
>          }
>     }
> }
>
>
> int main()
> {
>   Iterable it;
>   foreach (i; it.inReverse) writeln(i);
>   foreach (i; it.byStep(2)) writeln(i);
> }
>
>
> There is no need to add a special syntax to do what you want !
>
> Maybe there should be a bit more documentation about this.

I'll point out first that this solution allocates a closure on the heap --  
not necessarily the most efficient solution.

Second of all, this seems like a *lot* of trouble to go through just to  
call a function (yes, that's all you're doing).  The delegate returned is  
called *once* and then thrown away.

I'd much rather the language just support the most straightforward  
solution (calling a function with the given parameters).

-Steve