RE: A Blast from the Past

Jim,

Thanks for the clarification.  From the programmer's point of view, the
two implemetations of the named-constant contruct would be that they
work the same, so therefore they ARE the same.

But of course, the actual machine implementation might be quite
different (I don't quite follow that about "object stack" and "program
stack".

Hopefully, good programmers won't fall into that kind of sloppy
thinking! :)

-----Original Message-----
From: Jim Langston [mailto:jlangston@celsinc.com]
Sent: Tuesday, October 22, 2002 4:54 PM
To: 'mi400@midrange.com'
Subject: RE: [MI400] A Blast from the Past

Just a comment on the 2nd type.

If MI follows C, then they are not quite the same.

#Define NAMED-CONSTANT = 'ANYTHING'
When you use that in your program, the compiler will replace
NAMED-CONSTANT with 'ANYTHING'.

DD  CON  NAMED-CONSTANT  CHAR(10)  INIT('ANYTHING');
When you use that in your program, the compiler will the address of the
constant.

The main difference being that the #Define uses the object stack.  The
CON uses the program stack.

That's how it would work in C, anyway.  It may actually work different
in MI.

Regards,

Jim Langston

-----Original Message-----
From: Richard Hart [mailto:rhart@ATCDG.COM]

About two kinds of macros:

(1)  complicated ones
(2)  simple ones (as:  %Define CARRIAGE-RETURN = X'0D'  /* In Ascii */

The second kind is really just a named constant, right?  I guess we have
the

                DD  CON  NAMED-CONSTANT  CHAR(10)  INIT('ANYTHING');

Definition type for that.
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