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From: jan@janhh.hanse.de (Jan Willamowius)
Newsgroups: comp.lang.modula2
Subject: How to write NEW?
Message-ID: <5122672@janhh.hanse.de>
Date: 19 Apr 91 14:22:24 GMT
Organization: janhh, Atari UUCP server, Hamburg
Lines: 46

It looks like Wirth is using different ways to allocate memory
in different versions of his books. Sometimes he uses
'Allocate(Var,SIZE(Type)' and sometimes 'NEW(Var)'.

I like the second way better, but my compiler only supports Allocate.
So, is there a way to write a NEW (and DISPOSE, of course) ?

This is how far I got:
--- DEF ---
DEFINITION MODULE Storage;
FROM Heap IMPORT Allocate, Deallocate;
FROM SYSTEM IMPORT ADDRESS;

PROCEDURE NEW(VAR p : ADDRESS);

PROCEDURE DISPOSE(VAR p : ADDRESS);

END Storage.
--- IMP --
IMPLEMENTATION MODULE Storage;
FROM Heap IMPORT Allocate, Deallocate;
FROM SYSTEM IMPORT ADDRESS;

PROCEDURE NEW(VAR p : ADDRESS);
BEGIN
  Allocate(p,SIZE(p^));
END NEW;

PROCEDURE DISPOSE(VAR p : ADDRESS);
BEGIN
  Deallocate(p,SIZE(p^));
END DISPOSE;

BEGIN
END Storage.

The problem is that p 'looses' its type in the conversion to ADDRESS and
only a WORD is Allocated (ADDRESS is POINTER TO WORD).

Any ideas ?

Greetings, Jan

--
Jan Willamowius, Nienredder 6, 2000 Hamburg 54, Germany
E-Mail: jan@janhh.hanse.de