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From: rfb@lehman.com (Rick Busdiecker)
Subject: Re: Reference Counting (was Re: Searching Method for Incremental Garbage Collection)
In-Reply-To: mg@asp.camb.inmet.com's message of Fri, 2 Dec 1994 13:38:57 GMT
To: mg@asp.camb.inmet.com (Mitch Gart)
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References: <D06r8x.JBy@inmet.camb.inmet.com>
Date: Sun, 4 Dec 1994 01:06:01 GMT
Xref: glinda.oz.cs.cmu.edu comp.lang.c:119158 comp.lang.c++:101531 comp.lang.lisp:15915 comp.lang.ada:24354

In article <D06r8x.JBy@inmet.camb.inmet.com> mg@asp.camb.inmet.com (Mitch Gart) writes:

   In Lisp everything is a pointer.

Ugh.  This statement is simply false.  You *could* implement a lisp
that way, but it would be a bad idea.

Which data types are direct or indirect and when data is boxed or
unboxed varies across implementations, but in any real lisp
implementation, considerable effort is made to manipulate certain
classes of data (numbers, for example) directly rather than indirectly
through a pointer.

   If the following points are true about a reference counting scheme:

   - protects against memory leaks
   - predictable, guaranteed to not stop a program while doing GC
   - costs a bit, in proportion to how heavily pointers are used,
     but the cost is predictable
   - relatively simple to implement

   then RC sounds like a reasonable memory reclamation scheme for Ada.

Yes, if those points were true of RC then it would be a reasonable
scheme.

--
Rick Busdiecker <rfb@lehman.com>      Please do not send electronic junk mail!
  Lehman Brothers Inc.
  3 World Financial Center  "The more laws and order are made prominent, the
  New York, NY  10285-1100   more thieves and robbers there will be." --Lao Tzu
