Foreach on a template?

[Russell Lewis]

Daniel Keep wrote:
> Robin Allen wrote:
>> You can define an opApply in a template and use it like this:
>>
>> mytemplate!(int).opApply(int delegate(int v) {
>>
>>     ...loop...
>>     return 0;
>> });
>>
>> Which is what I had to do since D won't let you do this:
>>
>> foreach(v; mytemplate!(int))
>> {
>>     ...loop...
>> }
>>
>> The second one looks much nicer, and they both mean the same thing. So
>> why do we have to use the first?
>>
>> -Rob
> 
> Because "foreach(v ; mytemplate!(int))" expects "mytemplate!(int)" to be
> either an array or an object which has an opApply overload[*], so
> technically they *DON'T* mean the same thing.
> 
> 	-- Daniel
> 
> [*] Incidentally, have you tried specifying a function pointer or
> delegate to foreach instead?  Offhand, I think that was implemented a
> while back...

Another possibility is to have the template evaluate to a struct, and to 
implement opApply in that struct:
   template foo(args) {
     struct foo {
       int opApply(...) {...}
     }
   }