improving "cannot create instance of abstract class ..."

[Tydr Schnubbis]

Frank Benoit wrote:
> Would be nice if this message could also give a hint, why this class is
> abstract.
> 
> "cannot create instance of abstract class 'abc'. Method 'func' of
> interface 'MyInterface' is not implemented."

That last sentence in the error message looks like a pretty good hint to 
me.  You need to implement 'func', with the same signature as in 
MyInterface.