From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Using a string as a binary operator
Date: Tue, 14 Oct 2008 19:05:40 +0200
Date: 2008-10-14T19:05:43+02:00 [thread overview]
Message-ID: <1p57jbf1um2x8.1mk21y75746rt$.dlg@40tude.net> (raw)
In-Reply-To: 8cbb04c3-e789-4b67-897a-fd6f83486bbc@x16g2000prn.googlegroups.com
On Tue, 14 Oct 2008 08:35:23 -0700 (PDT), Joe wrote:
> I'm trying to build a simple stack the evaluates expressions in
> postfix notation (i.e. "1 2 +"). I can't find a way to use the
> operator directly when I get to it. When I get to the "+", but how
> do I apply this string to 1 and 2? The best I can do is make a case
> statement that has a case for each binary operator, but this seems
> very klunky. I know you can write "+"(1,2) to return 3 but how do I
> get Ada to recognize the string as an operator? Here's a short
> example of what I would like to do:
>
> with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
> procedure Operators is
> Plus : String := "+";
> begin
> Put( Plus(1,2));
> end Operators;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure Operators is
function Plus (L, R : Integer) return Integer renames "+";
begin
Put (Plus (1, 2));
end Operators;
P.S. I am quite sure that this is not what you need. You don't need strings
in order to evaluate an expression. Evaluation of an expression /= parsing
an expression. It is unclear which one you actually want, or maybe both.
P.P.S. Ada does not "recognize strings as operators." "+" when used to
declare or reference + is technically not a string. It is a string literal.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2008-10-14 17:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-14 15:35 Using a string as a binary operator Joe
2008-10-14 17:05 ` Dmitry A. Kazakov [this message]
2008-10-14 18:51 ` Jeffrey R. Carter
2008-10-15 15:22 ` Adam Beneschan
2008-10-15 17:23 ` Jeffrey R. Carter
2008-10-15 19:32 ` sjw
2008-10-16 8:14 ` Dmitry A. Kazakov
2008-10-14 22:01 ` george.priv
2008-10-15 3:51 ` Gene
2008-10-15 5:45 ` anon
2008-10-15 12:18 ` Joe
2008-10-15 13:43 ` John McCormick
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