mixin template as virtual function with variadic params not working

Derek Ney derek at hipgraphics.com
Wed Jul 23 07:22:54 PDT 2008


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




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