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[Chicken-users] Adding a free slot to Chicken symbols

From: John Cowan
Subject: [Chicken-users] Adding a free slot to Chicken symbols
Date: Sat, 1 Apr 2006 00:51:11 -0500
User-agent: Mutt/1.3.28i

This is a feature request for Chicken.  It's hopefully very simple to
implement, and it will be extremely useful for me, but it's a fairly deep
change to the system, and it will have impact on people who don't use it.

I'd like to have an extra slot provided with each symbol that can contain
any Chicken object.  Two primitive procedures (I propose symbol-slot
and symbol-slot-set!) will provide read and write access to the slot.
This will be very useful for implementing true property lists in my Lisp
1.5 emulator and for other purposes in my Joy interpreter.

The cost is, of course, that each symbol becomes 4 bytes bigger, and most
people will have no use for this feature, so it will be pure overhead.
OTOH, most programs don't have zillions of symbols at run time, either,
so perhaps it's not that expensive.

Unfortunately, I don't know enough about the Chicken implementation to
propose a patch.

John Cowan      address@hidden
Be yourself.  Especially do not feign a working knowledge of RDF where
no such knowledge exists.  Neither be cynical about RELAX NG; for in
the face of all aridity and disenchantment in the world of markup,
James Clark is as perennial as the grass.  --DeXiderata, Sean McGrath

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