NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/comp/lang/modula3/1148

Text File | 1993-01-25 | 1.4 KB | 69 lines

Newsgroups: comp.lang.modula3
Path: sparky!uunet!newsgate.watson.ibm.com!yktnews2.watson.ibm.com!yktnews!admin!rhoover
From: [e-mail] (Roger Hoover)
Subject: generics that use generics
Sender: [e-mail] (NNTP News Poster)
Message-ID: <[e-mail]>
Date: Mon, 25 Jan 1993 14:28:56 GMT
Disclaimer: This posting represents the poster's views, not necessarily those of IBM
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Organization: IBM T.J. Watson Research Center
Lines: 56


I'd like to write a generic that extends another generic.  For
example, consider the generic List:

--
GENERIC INTERFACE List(El);

TYPE T <: REFANY;

PROCEDURE RemoveFirst(VAR l: T): El.T;
PROCEDURE InsertFirst(VAR l: T, x: El.T);

END List.

--
GENERIC MODULE List(El);

REVEAL
  T = BRANDED OBJECT
    el: El.T;
    next: T := NIL;
  END;

PROCEDURE RemoveFirst(VAR l: T): El.T =
VAR r: El.T;
BEGIN
  <*ASSERT l # NIL*>
  r := l.el
  l := l.next;
  RETURN r
END RemoveFirst;

PROCEDURE InsertFirst(VAR l: T, x: El.T) =
BEGIN
  l := NEW(T, el := x, next := l)
END InsertFirst;

END List.

--
I'd like to create a generic Stack that uses List:
GENERIC INTERFACE Stack(El);

TYPE T <: REFANY;

PROCEDURE Pop(VAR l: T): El.T;
PROCEDURE Push(VAR l: T, x: El.T);

END Stack.

Is there any way to write GENERIC MODULE Stack(El) using the
List.RemoveFirst procedure for Pop and ListInsertFirst for
Push?

roger
[e-mail]