NetNews Usenet Archive 1992 #26/NN_1992_26.iso/spool/comp/lang/modula3/1027

Text File | 1992-11-12 | 1.3 KB | 65 lines

Newsgroups: comp.lang.modula3
Path: sparky!uunet!walter!att-out!pacbell.com!ames!haven.umd.edu!decuac!pa.dec.com!src.dec.com!Roger Hoover <[e-mail]>
From: Roger Hoover <[e-mail]>
Subject: generics that use generics
To: m3
Message-ID: <[e-mail]>
Cc: [e-mail]
X-External-Networks: yes
Date: Thu, 12 Nov 92 14:55:54 EST
Lines: 53


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]