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From: hiebeler@csv.rpi.edu (David Hiebeler)
Newsgroups: comp.lang.modula2
Subject: Re: some questions about modula2
Message-ID: <15@rpicsb8>
Date: Thu, 13-Aug-87 17:52:00 EDT
Article-I.D.: rpicsb8.15
Posted: Thu Aug 13 17:52:00 1987
Date-Received: Sat, 15-Aug-87 10:31:01 EDT
Sender: nobody@rpicsb8
Reply-To: hiebeler@csv.rpi.edu (David Hiebeler)
Organization: RPI CS Dept, Troy, New York
Lines: 36
Keywords: modula2, type, vars

References:


I will answer what I can in no order whatsoever.
4.  Exported procedures may reference variables which are 'hidden' in that
module, i.e. not exported.  I have a random # generator with a procedure
which looks something like this.
PROCEDURE Rndom():CARDINAL;
(* Return a CARDINAL between 0 and 999 *)
BEGIN
  Seed := sqrt(Seed);
  IF Seed<10 THEN Seed := (Seed+2)*Seed*Seed*Seed (* keep Seed from *)
						   (* getting too small *)
  END; (* IF *)
  RETURN TRUNC((Seed-TRUNC(Seed))*1000) (* or something like that, I forget *)
				      (* to get the first 3 decimal places *)
END Rndom;
-- Note this will update the Seed, which is invisible to the calling
module.  (I also have a procedure InitSeed
PROCEDURE InitSeed(NewSeed:REAL);
BEGIN
  Seed := NewSeed;
  IF Seed<10 THEN Seed := (Seed+11)*(Seed+1)*(Seed+1)*(Seed+1)
  END;  (* IF *)                 (* or something like this *)
END InitSeed;


2.  (Was it 2?)  A definition module referencing a type declared in the
implementation module.  -- Why would you want to do this?  It must be
a 'hidden' type, or you would declare it to be exported in the definition
module.  The only reason you need mention it in the definition is if
say, a procedure needs a var of that type as a parameter, in which
case, the type would have to be exported anyways.

                             -D.H.
----
David Hiebeler       hiebeler@csv.rpi.edu
Chatham, NY         "Illusions, Richard!  Every
(also Troy, NY)      bit of it illusions!"