Balagopal Komarath wrote:
On Wednesday, 14 June 2017 at 09:41:49 UTC, ketmar wrote:
Balagopal Komarath wrote:
Why doesn't this work? The Test!Duck type has a void quack() method but
the compiler says it is not implemented.
'cause `alias this` is *not* a tool that can be used to emulate
inheritance. no, `quack` is NOT impemented. `alias this` won't
automagically paste the code.
Thanks for the reply. Is there any reason for disallowing this? AFAIK,
the alias this guarantees that the interface provided by Test!T is a
superset of the interface provided by T. And, when T = Duck, T provides
everything required by IDuck. Couldn't the compiler check while
instantiating that Test!Duck provides all methods required by IDuck?
besides improper using of `alias this`, there is a technical reason too:
`struct` is not a `class`, it doesn't have VMT, and other class goodies. as
i said, `alias this` is not a macro, it doesn't paste code, it just tells
the compiler to make "symbol redirection" on typechecking. interfaces
*require* a full-featured class, with VMT, and some hidden pointers to
support hidden interface machinery.
