Re: Equality operator overloading in ADA 83

[mheaney@ni.net (Matthew Heaney)]

In article <dewar.862097010@merv>, dewar@merv.cs.nyu.edu (Robert Dewar) wrote:

>In general, this principle is good, and I tried to obey it in RM95 -- if
>something is undefined, then the RM should say so explicitly.  Nothing
>should be undefined just because the RM doesn't bother to define it.
>
>Anyway, this is why we have an AI on this point.>>

Robert said:

>I do not disagree that it is a good idea to pin down this particular
>lack of specification, but I strongly disagree with the general principle
>here. The idea of a package spec in Ada 83 or Ada 95 is that you are
>free to implement the body anyway you like, and of course there are things
>that are left open. FOr example, the paragraph above would require us to
>say things like:
>
>a) it is implementation defined what the value of x'size is for the following
>types (Address, Unbounded_String, ...)

[pedantry snipped :-)]

Robert, you're being a wee bit pedantic, don't you think?  We simply need
to specify the _external_ behavior of type Bounded_String, specifically the
behavior of equality, under _all_ circumstances, including those times when
predefined operators re-emerge.  No one is suggesting we publically specify
the any aspects of the _representation_ of Bounded_String.

Perhaps the real issue is, What does "representation" mean?  You assume
equality is a representation issue, others assume equality is not a
representation issue (ie is external behavior).  So let's resolve _that_
ambiguity.

--------------------------------------------------------------------
Matthew Heaney
Software Development Consultant
<mailto:matthew_heaney@acm.org>
(818) 985-1271