Re: Tagged objects

[David Chisnall]

On 21 Jul 2011, at 15:13, Dr. H. Nikolaus Schaller wrote:

> Am 21.07.2011 um 15:22 schrieb Thomas Davie:
> 
>> Hey,
>> 
>> I wondered if you guys had seen the fun and games that apple have been 
>> having abusing the last bit of pointers to make boxing and unboxing 
>> NSNumbers (and some others) much much faster…
>> 
>> http://objectivistc.tumblr.com/post/7872364181/tagged-pointers-and-fast-pathed-cfnumber-integers-in
> 
> Nice idea. I hope they have not tried to patent it.
> 
> Here is some prior art:
> 
> "DYNAMIC MEMORY MANAGEMENT FOR APL-LIKE LANGUAGES", Rodnay Zaks, Universite 
> de Technologie de Compiegne, France, Proceedings of ACM SIGPLAN-SIGMICRO 
> Interface Meeting, Arden House, New York, May 30-June 1, 1973.
> 
> Even older than Apple, Inc. :)

That's a bit modern.  This technique was used by Lisp in 1958.  Smalltalk, in 
1976, copied the Lisp implementation and did the same thing.  All modern 
Smalltalk implementations (including the one in Étoilé) use this technique.

David