Re: friend classes in ada95

[Robert Dewar <robert_dewar@my-deja.com>]

In article <38FB8556.4EACD391@earthlink.net>,
  "Robert I. Eachus" <rieachus@earthlink.net> wrote:
> (To me the silliest of the issues with
> such potential was
> about whether or not to allow leading underscores in
> identifiers...)

Silly enough for you to have forgotten the issue :-) The issue
was whether to treat underscores as letters in identifiers,
removing the restrictions on the use of underscores. Actually
the example most often used was a trailing underscore, but the
general ability to mirror c identifiers such as a__b was also
an issue.

> IMHO, the changed to the treatment of abstract made at a later
> Boston meeting probably would not have been possible with the
> syntax proposed by Jean Ichbiah.

That's plain wrong, or a misunderstanding, the notation

  class type x is record ...

as simply a syntactic transformation of

  type x is tagged record ...

is completely neutral with respect to such changes (indeed
an Ada 95 compiler today could if it liked accept the first
time as a source representation of the second form (though
this kind of stretching of the notion of source representation
is considered unsporting, even if allowed by the RM :-)

 To change the meaning of class as a technical
> term would require significant additional work by the Language
Design
> Team--unless they were allowed to unify the existing class
hierarchy and
> the new class constructs.  But this had been explicitly
considered and
> rejected much earlier in the design process.  So those arguing
for class
> as a keyword had to justify the extra effort.


TO use this as an argument against the class syntax suggestion
is allowing best to be the enemy of good. The class syntax
could perfectly well be introduced without changing the notion
of classes.

After all, to most Ada 95 programmers

  type x is tagged record ...

introduces a new class called x anyway, sure I know that is
not quite right, but there are lots of cases where informal
usage does not match the RM :-)


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