Re: HELP: renames and enum values

["Samuel T. Harris" <samuel_t_harris@Raytheon.com>]

John English wrote:
> 
> Dale Stanbrough wrote:
> > All i was attempting to say is that
> >
> >    type blah renames bleh;
> >
> > could be predicted to have the same semantics as a subtype
> > declaration (this would be the "other way" of performing
> > subtyping).
> >
> > I know what beginners think of, because I had 8 years of
> > teaching beginners. This is something that some of them
> > thought of (but not many because most of them were introduced
> > to subtypes long before renames!).
> 
> What's even less obvious is the way to rename enumeration literals:
> 
>  function Enum_Literal return Enum_Type renames Other_Enum_Literal;
> 
> Now, that *really* confuses them, and none of them would ever be
> able to guess it without being told!
> 

Perhaps I am not "one of them" since I figured this out
quickly the first time I ran into this renaming problem
way back in my youth. I learned Ada 83 by reading the
reference manual long before I had a compiler to play
with. During my initial reading, I found it strange that
enumeration literals would be defined as parameterless
functions. A little introspection quickly revealed the
necessity of this semantic definition to allow the same
literal to be used in different enumeration type definitions.

When I later actually had a compiler to use and needed to
rename some enumeration literals, the function renames
was the first thing I thought of. I actually did not
expect the compiler to accept it, figuring the semantic
definition was just some standarized sugar but was
pleasantly surprise with the successful results.

-- 
Samuel T. Harris, Principal Engineer
Raytheon, Aerospace Engineering Services
"If you can make it, We can fake it!"