Robert Fraser Wrote: > Steve Teale wrote: > > template isInputRange(R) > > { > > enum bool isInputRange = is(typeof( > > { > > R r; // can define a range object > > if (r.empty) {} // can test for empty > > r.popFront; // can invoke next > > auto h = r.front; // can get the front of the range > > }())); > > } > > > > I can not possibly be the only D enthusiast who finds this completely > > incomprehensible. > > Yeah, that one is a bit tricky, and what makes it worse is that it seems > officially sanctioned by Walter/Andrei as the "right way" to check if a > type supports some operations. Basically, if you have: > > is(typeof({ @@@ }())); > > this means "if I made a function containing @@@, would that function > compile?". It's a hack which stems from the way the is expression works. > > > What is a range? > > As others have mentioned, it's just a struct (or other type) that > happens to support certain operations.
So does this mean that interfaces are just a tragic mistake. I'd always thought that what you said was a pretty good description of what an interface is!