Sean Eskapp wrote:
> I remember in C++, I had to do double-dispatch using the visitor pattern.
> This is cumbersome, just because each subclass has to have the exact same
> singly-dispatched code that looks like:
>
> void dispatch(Base& other)
> {
> other.dispatch(*this);
> }
>
> Is there a nicer way to do this in D, or am I stuck with the same thing?
There isn't really, but you can take out some of the boilerplate with a
mixin, which goes a long way:
// The template parameter Visitor is not actually needed, depending on
// what you want to do
mixin template Accept(Visitor)
{
void accept(Visitor v)
{
v.visit(this);
}
}
class Stuff
{
mixin Accept!IStuffVisitor;
}
With some ctfe it's also not too hard to take out the boilerplate of
creating the visitor interface with a bit of code generation, though I'm not
sure if it's worth it.
