I am trying to create a set of methods that take a variable number of arguments (at compile time). I would have liked to have used template functions to do that, but I need the functions to be virtual, and template functions cannot be virtual. So I thought I would try to use a mixin of a variadic template function. But I am getting a weird compiler error with my simple test program. Here is the test program:

     1  import std.stdio;
     2
     3  template TCALL(ARGS...)
     4  {
     5    void makecall(ARGS args)
     6    {
     7      writefln("tcall...", args);
     8    }
     9  }
    10
    11  mixin TCALL!();
    12  mixin TCALL!(int);
    13  mixin TCALL!(int,int);
    14
    15
    16  class Method
    17  {
    18    mixin TCALL!();
    19    mixin TCALL!(int);
    20    mixin TCALL!(int,int);
    21  }
    22
    23  void main()
    24  {
    25    auto m = new Method;
    26
    27    m.makecall(0,1);
    28    makecall(0,1);
    29  }

And when I compile with "Digital Mars D Compiler v2.014" I get this error:

test6.d(27): Error: m.makecall is not a declaration
test6.d(27): Error: function expected before (), not 1 of type int

Can anyone explain what is going on here? It seems like it should work. Note that if you comment out line 27 and compile it compiles fine and runs producing the expected output:

tcall...01

-Thanks, Derek

"Derek Ney" <derek@hipgraphics.com> wrote in message news:g67eru$276j$1@digitalmars.com...
>I am trying to create a set of methods that take a variable number of arguments (at compile time). I would have liked to have used template functions to do that, but I need the functions to be virtual, and template functions cannot be virtual. So I thought I would try to use a mixin of a variadic template function. But I am getting a weird compiler error with my simple test program. Here is the test program:
>
>     1  import std.stdio;
>     2
>     3  template TCALL(ARGS...)
>     4  {
>     5    void makecall(ARGS args)
>     6    {
>     7      writefln("tcall...", args);
>     8    }
>     9  }
>    10
>    11  mixin TCALL!();
>    12  mixin TCALL!(int);
>    13  mixin TCALL!(int,int);
>    14
>    15
>    16  class Method
>    17  {
>    18    mixin TCALL!();
>    19    mixin TCALL!(int);
>    20    mixin TCALL!(int,int);
>    21  }
>    22
>    23  void main()
>    24  {
>    25    auto m = new Method;
>    26
>    27    m.makecall(0,1);
>    28    makecall(0,1);
>    29  }
>
> And when I compile with "Digital Mars D Compiler v2.014" I get this error:
>
> test6.d(27): Error: m.makecall is not a declaration
> test6.d(27): Error: function expected before (), not 1 of type int
>
> Can anyone explain what is going on here? It seems like it should work. Note that if you comment out line 27 and compile it compiles fine and runs producing the expected output:
>
> tcall...01
>
> -Thanks, Derek

My guess is that it's a bug.  If you only mix in one version (say, the (int, int) version), it works, and it's virtual.  And the global versions work fine.  I'd expect the methods to work fine as well.