This works per documentation:

void function(int) dg;

void dothis(int x)
{
   printf("%d\n", x);
}

void main(char[][] args)
{
   dg = &dothis;
   dg(5);
}

However, if I put the declaration of dg in another file (test2.d in this  case) I get:

Error 42: Symbol undefined _D5test22dgPFiZv

It works if I put test2.d in the build command line, but why is the linker looking for a function pointer?

Thanks,
Paul

Paul Runde wrote:
> It works if I put test2.d in the build command line, but why is the linker looking for a function pointer?

It's a piece of global data just like any other.  It's equivalent to the C++:

test.cpp:

   #include "test2.h"

   void dothis(int x) { printf("%d\n", x); }

   int main(char** args) {
      dg = &dothis;
      dg(5);
   }

test2.cpp:
   void (*dg)(int);

test2.h:
   extern void (*dg)(int);

The difference is that D doesn't need a separate .h file.

 -- andy