Reply to Robert,
> This is already possible via template mixins (sort of, but alias
> template params are required to access fields), but explicit partials
> might be quite helpful.
IIRC this works. Or did I misread you?
template Foo()
{
  int get(){ return foo; }
  void set foo(int i){foo = i;}
}
class Bar
{
  int foo;
  mixin foo!();
}