• Sean Kelly (31/31) Sep 19 2007 I've been playing with template functions over the past few days and
• Janice Caron (6/7) Sep 19 2007 Shouldn't that be
• Sean Kelly (3/12) Sep 19 2007 Perhaps, but I get the same error with and without "alias."

Sean Kelly <sean f4.ca> writes:

I've been playing with template functions over the past few days and 
have been wondering about how much detail they should be able to infer 
about a parameter.  In particular, template template parameters seem to 
have only limited support.  For example:

     class One(T) {}
     class Two(T, U) {}

     void fnA(T)( One!(T) val ) {}
     void fnB(T,U)( T!(U) val ) {}
     void fnC(T...)( Two!(T) val ) {}


     void main()
     {
         fnA( new One!(int) );
         // works

         fnB( new One!(int) );
         // test.d(14): template test.fnB(T,U) does not match any
         //             template declaration
         // test.d(14): template test.fnB(T,U) cannot deduce template
         //             function from argument types (One)


         fnB!(One,int)( new One!(int) );
         // test.d(21): template instance fnB!(One,int) does not match
         //             any template declaration
         // test.d(21): Error: template instance 'fnB!(One,int)' is not
         //             a variable


         fnC( new Two!(int,int) );
         // test.d(27): template test.fnC(T...) does not match any
         //             template declaration
         // test.d(27): template test.fnC(T...) cannot deduce template
         //             function from argument types (Two)
     }

Which of the above functions /should/ work?


Sean

"Janice Caron" <caron800 googlemail.com> writes:

On 9/19/07, Sean Kelly <sean f4.ca> wrote:
      void fnB(T,U)( T!(U) val ) {}

Shouldn't that be
void fnB(alias T,U)( T!(U) val ) {}
?

I could be wrong, but I thought "alias" was necessary if you want a
template template parameter.

Sean Kelly <sean f4.ca> writes:

Janice Caron wrote:
 On 9/19/07, Sean Kelly <sean f4.ca> wrote:
      void fnB(T,U)( T!(U) val ) {}

 
 Shouldn't that be
 void fnB(alias T,U)( T!(U) val ) {}
 ?
 
 I could be wrong, but I thought "alias" was necessary if you want a
 template template parameter.

Perhaps, but I get the same error with and without "alias."


Sean