[gclist] object identity & copying collection

Charles Fiterman cef@geodesic.com
Wed, 10 Dec 1997 09:20:40 -0600

The problem is in the object identity not the hash function.

Some objects need identities that can survive a move.
In copying collectors that means all objects or close
to it. We designate these as movable objects.

The safe way to do this is to have identity source objects
with unique 64 bit identity bases. By unique I mean there
is one source for these numbers. Maybe they are associated 
with machines and when you build a machine you hand out a 
unique number. You go to the identity source source at the 
start of the month and say "I need 10^7 numbers." and they 
give them to you.

Each identity source gives out 128 bit identities which
are unique to the galaxy. No lossy compression, no games,
no chance of error until the 64 bit numbers run out. Our
silicon descendants can worry about it a billion years
after the last human has died in a zoo. They will call
it the year 1,987,888,905.5513 bug.

This suggests deep problems with copying collectors
and object orientation.

Charles Fiterman		Geodesic Systems
414 North Orleans Suite 410	Phone 312 832 1221 x223
Chicago IL 60610-4418		FAX   312 832 1230

A young man saw a product advertised in a magazine that said
"Guaranteed 100% effective against bugs when properly used."
He sent away and got two blocks of wood with the instructions
"Place bug on block A, strike sharply with block B." Debuggers
are like that, and you can get stung while using them. Great
Circle tries to be something better than that.