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From: ka@socrates.hr.att.com (Kenneth Almquist)
Subject: Re: Ada self-referential operators
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References: <3gnkjb$gso@miranda.gmrc.gecm.com> <3grqrf$jkd@gnat.cs.nyu.edu>
Date: Mon, 6 Feb 1995 20:51:23 GMT
Date: 1995-02-06T20:51:23+00:00
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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