On Thursday, 11 July 2013 at 11:56:16 UTC, Gary Willoughby wrote:
Any idea what i'm doing wrong?
Function templates cannot be virtual. You're allowed to declare
non-virtual members of interfaces, but they must be defined. That
means static functions, final functions and function templates
can be declared in interfaces as long as they are defined. This
is a feature of D.
However, in my opinion, it's a bug that you're allowed to declare
a function template (when using the shortcut syntax) without
defining it, whether in an interface or not. This is a rather
natural bug though, due to the nature of function templates:
void a()();
is equivalent of:
template a() { void a(); }
Perhaps it makes sense to allow the declaration without
definition when the template and function are explicitly
separated (can anyone think of a case where this is useful? Maybe
mixin-related?), but when using the former syntax - the function
template syntax - I don't think it makes any sense.
Whether or not function templates in general should be declarable
without a definition, it's definitely a bug that you can do it in
an interface.
