Re: Ada self-referential operators

[ka@socrates.hr.att.com (Kenneth Almquist)]

Robert Dewar <dewar@cs.nyu.edu> wrote:
> It is not that I think :+= is peculiar because it is not in the RM, rather
> +:= is not in the RM because it is peculiar, i.e. it would be VERY difficult
> to put it in without running into nasty semantic ramifications.

Perhaps I'm missing them.  What about the following rules?

1.  For each function of the form

          function "+"(L: type_1; R: type_2) return type_1;

    where type_1 is not limited, implicitly define:

          procedure "+:=" (L: in out type_1; R: in type_2) is
          begin
              L := L + R;
          end "+:=";

    These implicit definitions should behave similarly to the implicit
    definitions of "/=" which occur in Ada 83 and Ada 95.  Explicit
    defintions of "+:=" are illegal.

2.  If a statement of the form "A +:= B;" is encountered, treat it as
    the procedure call "+:="(A, B).
					Kenneth Almquist