Sharing inheritance ?

From: Christophe Raffalli (
Date: Mon Nov 02 1998 - 10:32:08 MET

Date: Mon, 02 Nov 1998 10:32:08 +0100
From: Christophe Raffalli <>
Subject: Sharing inheritance ?

I have a problem with the following situation:

class a (x : int) =
    val mutable v = x 
    method get = v
    method set x = v <- x
class b x =
  object (self)
    inherit a x as super
    method getb = self#get
    method setb = self#set
    method oldget = super#get
class c x =
  object (self)
    inherit a x
    method getc = self#get
    method setc = self#set
class d x = 
    inherit b x
    inherit c x
(* produces:
Warning: the following methods are overriden by the inherited class:
  get set
Warning: this definition of an instance variable v hides a previously
defined instance variable of the same name

let o = new d 2;; o#setb 3;; o#getc;; (* produces 3 *) o#oldget;; (* produces 2 *)


I understand what is happening, but I would prefer is the default semantic was two merge two values with the same name in an object (giving a type error if their types can not unify).

Then one could have a syntactic sugar to change the name of some value:

class d x = object inherit b x inherit c x with v -> v' end ;; To ask to rename the value v from b as v'. Together with the possibility to bind a name to acces old method, this will allow a total flexibility (I can always do what I want) which is not the case now.


Moreover, the follwing would become possible:

class d = object inherit b 0 with v -> v0 as b0 inherit b 1 with v -> v1 as b1 inherit b 2 with v -> v2 as b2 end ;;

Christophe Raffalli Universite de Savoie

PS: do not forget to add "inherit" and "open ... in" for structure in the next release, that will make some program simpler.

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