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From: CARTER@MITBATES.BITNET (Tony Carter - MIT Bates Linac)
Newsgroups: comp.os.vms
Subject: Using the message facility with Pascal
Message-ID: <8711081007.AA04519@ucbvax.Berkeley.EDU>
Date: Wed, 4-Nov-87 14:37:00 EST
Article-I.D.: ucbvax.8711081007.AA04519
Posted: Wed Nov  4 14:37:00 1987
Date-Received: Tue, 10-Nov-87 07:33:04 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 45

>The trick is to declare some [EXTERNAL] variables with the same name as
>the condition code symbols that you defined in your message file.

Close, what you really want to use is [EXTERNAL,VALUE]. This will cause
the reference to get resolved properly. For example:

  VAR
    MSG_MESSAGE : [EXTERNAL,VALUE] UNSIGNED;

  BEGIN
    LIB$SIGNAL(MSG_MESSAGE);
  END.

I know the compiler will not let you use the variable on the left hand side
of an assignment statement, but I don't know if that means it is handled like
a constant or if memory is allocated for it like a variable.

As far as how to declare LIB$SIGNAL to get it to like your FAO args, I use:

[asynchronous,external] function lib$signal
        (%immed SigVal : unsigned;
         %immed FaoCnt : integer :=%immed 0;
         %stdescr faoargs : [list] packed array[$l0..$u0:integer]
                                    of char):unsigned;extern;

To use it, you could have:

  { no FAO args }
  LIB$SIGNAL(MSG_MESSAGE);
  { one string arg }
  LIB$SIGNAL(MSG_MESSAGE,1,'SOME STRING');
  { one numeric arg (352) }
  LIB$SIGNAL(MSG_MESSAGE,1,%IMMED(352));
  { one string arg and one numeric arg }
  LIB$SIGNAL(MSG_MESSAGE,2,'SOME STRING',%IMMED(352));
  etc...

The %IMMED(352) is necessary because I directed the compiler to pass by
CLASS_S string descriptor by default. Obviously, you can insert the
appropriate variables in place of the values I used in the example.

Tony Carter        CARTER@MITBATES (Bitnet)
(617) 245-6600
MIT Bates Linac
Middleton, MA