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Re: constant folding/smashing
Date: Thu, 9 Jun 88 14:59:16 PDT
From: Jon L White <email@example.com>
re: My point is that in the form
(SETF (SYMBOL-VALUE (QUOTE X)) 1)
the quoted object is no more or less "constant" than in the form
(SETF (FIRST (QUOTE (A B C))) 1)
So why does QUOTE make the components of the list (1 2 3)
unmodifiable but not the components of X?
Because the semantic model of symbols doesn't consider them to have
modifiable components; they are "atomic". In fact, several implementations
I'm familiar do a "spaghetti-stack" lookup for the SYMBOL-VALUE function --
not a structure-component fetch. And there have been serious suggestions for
flushing the symbol-plist notion in favor of hashtables, or at least
encouraging one to use hashtable entries rather than plist entries.