Re: Overloading for T and T'Class

[comar@cs.nyu.edu (Cyrille Comar)]

dweller@Starbase.NeoSoft.COM (David Weller) writes:
: In article <Cz4H8G.MA@swlvx2.msd.ray.com>,
: John Volan <jgv@swl.msd.ray.com> wrote:
: >In Ada9X, is it legal to overload the same subprogram name for both
: >some tagged type T and its class-wide type T'Class?  For example:
: >
: >	package P is
: >	  type T is tagged ... ;
: >	  procedure Op (X : in out T);
: >	  procedure Op (X : in out T'Class);
: >	  ...
: >	end P;
: >
: 
: As a compiler, your declarations would confuse me, since the first Op
: says "I'm a primitive operation, and thus I may be extended and
: modified by descendants", and the second one says, "I'm a classwide
: operation, thus any descendant of my type (a member of T'Class) must
: execute this subprogram".  A contradiction, from my perspective.
: 
: I think GNAT (at the moment) permits this, further confusing the
: issue.

My understanding (without checking the RM...) is that the above declarations
are legal but that any USE of "Op" would be ambiguate, so it is really
useless... 
I am not completely sure though...




-- 
------------------------------------------------------------------------
Cyrille Comar,                                  E-mail: comar@cs.nyu.edu
Gnat Project                                    US phone: (212) 998-3489