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From: mg@harp.camb.inmet.com (Mitch Gart)
Subject: Re: Garbage Collection in Ada
Date: 1996/10/31
Message-ID: <E055IC.26I.0.-s@inmet.camb.inmet.com>#1/1
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Date: 1996-10-31T00:00:00+00:00
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Jonas Nygren (ehsjony@ehs.ericsson.se) wrote:

(snip)

: package Collected is

:    type Object is
:       tagged record
:          Reference_Count : Natural;
:       end record;
:    type Object_Access is access all Object'Class;

:    type Handle is new Ada.Finalization with
:       record
:          Ref : Object_Access;
:       end record;

: end Collected;

(snip)

This suffers from several problems:

- If you provide a function to do allocations,

    function Allocate_Obj return Handle;

  and users use this function, things work well, but if a user calls
  "new Object" directly things don't work at all.  

- Obj1 := Obj2;      doesn't work because the reference count value is
  copied.  If Obj2's count is 3 before the assignment, after the assignment
  Obj1's count is also 3 which is probably wrong.

Mitch Gart