Hashing "object identities"

[Nick Levine]

For the structures you'll have to use EQUALP. So your question as I understand it is how to incorporate that into lookup of the triples. 

You might have an EQUALP table which maps each structure into a number, and then the main lookup is keyed on a triple of numbers.

Or maybe, if speed is more important than space, each structure contains an ID slot -- a unique number -- and you key off that. 

- nick

> On 3 Dec 2017, at 12:02, Antoniotti Marco <antoniotti.marco at disco.unimib.it> wrote:
> 
> Hi
> 
> I am fooling around with a problem that eventually will have to use a hash table on “triples” of “integers” and “structures".  Triples I can portably pass to the EQUAL hash table.  I cannot use an EQUALP hash table, because I would end up wasting to much time.
> 
> Here is the rub:  my triples <N, O1, O2> need to use the “object identity” of O1 and O2 (two structs).  I could switch to an EQL hash table keyed on (HASH-TRIPLE-KEY N O1 O2).  How would you proceed (or write HASH-TRIPLE), while staying as much portable as possible?  As you well know SXHASH is practically useless.
> 
> Thanks
> —
> Marco
> 
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> 
> 
> 
> 
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