Right, I have this:

template foo(T)
{
    int opApply(int delegate(ref T) dg)
    {
        // code here
    }
}

class bar(T)
{
    mixin foo!(T) baz;
}

void main()
{
    bar b = new bar();
    foreach(qux; bar.baz)
    {
    }
}

And it does not compile. The error I get is "expression has no value", on the line with the foreach. Do I need to do this in a different way, or is it simply not possible (at the moment)?

-- 
Simen

On Wed, 12 Nov 2008 04:57:41 +0100, "Simen Kjaeraas" <simen.kjaras@gmail.com> wrote:

>Right, I have this:
>
>template foo(T)
>{
>     int opApply(int delegate(ref T) dg)
>     {
>         // code here
>     }
>}
>
>class bar(T)
>{
>     mixin foo!(T) baz;
>}
>
>void main()
>{
>     bar b = new bar();
>     foreach(qux; bar.baz)
>     {
>     }
>}
>
>And it does not compile. The error I get is "expression has no value", on the line with the foreach. Do I need to do this in a different way, or is it simply not possible (at the moment)?

According to the spec, Aggregate in foreach can be array, class, struct or tuple. I don't know why template instances or mixins with opApply were not included. Hopefully, when foreach is updated to work with ranges, everything that looks like a range will be acceptable.

Em Wed, 12 Nov 2008 01:57:41 -0200, Simen Kjaeraas <simen.kjaras@gmail.com> escreveu:

> Right, I have this:
>
> template foo(T)
> {
>      int opApply(int delegate(ref T) dg)
>      {
>          // code here
>      }
> }
>
> class bar(T)
> {
>      mixin foo!(T) baz;
> }
>
> void main()
> {
>      bar b = new bar();
>      foreach(qux; bar.baz)
>      {
>      }
> }
>
> And it does not compile. The error I get is "expression has no value", on the line with the foreach. Do I need to do this in a different way, or is it simply not possible (at the moment)?
>

Currently the right way to do this is:

template foo(T)
{
    int opApply(int delegate(ref T) dg)
    {
        // code
    }
}

class bar(T)
{
    mixin foo!(T);
}

void main()
{
    auto b = new bar!(int);
    foreach(qux; b)
    {
    }
}

-- 
Usando o revolucionário cliente de e-mail do Opera: http://www.opera.com/mail/

On Wed, 12 Nov 2008 11:37:33 +0100, Christian Hartung <christian.s77@gmail.com> wrote:

> Currently the right way to do this is:
>
> template foo(T)
> {
>      int opApply(int delegate(ref T) dg)
>      {
>          // code
>      }
> }
>
> class bar(T)
> {
>      mixin foo!(T);
> }
>
> void main()
> {
>      auto b = new bar!(int);
>      foreach(qux; b)
>      {
>      }
> }
>

Ah, but that does not give me the named mixin.

Consider

class Tree(T)
{
	mixin Traverse!(Stack) depthfirst;
	mixin Traverse!(Queue) breadthfirst;
}

-- 
Simen