Code example for function/delegate as template argument ?

[Basile B. via Digitalmars-d-learn]

On Wednesday, 4 May 2016 at 06:21:36 UTC, chmike wrote:
> Hello,
>
> I failed to find some code example for a template class/struct 
> that accept a function/delegate as template argument. All 
> examples I could find use simple value types like int or double.
>
>
> I piggy bag another question. Defining a function/delegate as 
> function argument is shown in examples. What I could not find 
> is how would I pass an object instance with a method to call ? 
> In C++ we use std::bind. How do we do that in D ?

As for the second question, finding the right method dynamically 
(virtual method or interface) is easy so I suppose you want to 
find a member using D reflection.
Here is a quick example:

----
struct Bar
{
     void fun(string text) {text.writeln;}
}

struct Foo
{
     void delegate(string) dg;

     this(T)(T t)
     {
         foreach(member; __traits(allMembers, T))
         {
             foreach(i, overload; __traits(getOverloads, T, 
member)[])
             {
                 auto overloadDg = &__traits(getOverloads, t, 
member)[i];
                 static if (is(typeof(overloadDg) == typeof(dg)))
                 {
                     dg = &__traits(getOverloads, t, member)[i];
                     break;
                 }
             }
         }
         if (dg)
             dg("found");
     }
}

void main(string[] args)
{
     Bar bar;
     Foo foo = Foo(bar);
}
----

More checkings are possible. Here I just verify that a pointer to 
a member function is of same type as the delegate to assign.