Hashing "object identities"

[Daniel Kochmański]

On 03.12.2017 12:41, Antoniotti Marco wrote:
> Let me also add that I am being deliberately withholding information on what exactly I am working on/fooling around with :)  There is an obvious solution based on keeping a table of such objects; alas, it would require manually garbage collecting it.  I’d like to let the GC do the work.
What about weak hash tables? They are supported by most implementations 
(and have portability layer in form of a library trivial-garbage).
>
> Cheers
> —
> MA
>
Regards,
Daniel
>
>
>
>> On Dec 3, 2017, at 12:38 , Antoniotti Marco <antoniotti.marco at disco.unimib.it> wrote:
>>
>>> On Dec 3, 2017, at 12:27 , Jason Cornez <jcornez at alum.mit.edu> wrote:
>>>
>>> Add an integer slot on the structs; hash on that?  -Jason
>> I forgot to mention it.  THAT is another thing I want to avoid because I need to share subgraphs (DAGs).  I need to hash on the “object identity”.
>>
>> Cheers
>> —
>> MA
>>
>>
>>
>>
>>
>>
>>> Sent from my iPhone
>>>
>>>> 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
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Marco Antoniotti, Associate Professor        tel.    +39 - 02 64 48 79 01
>>>> DISCo, Università Milano Bicocca U14 2043        http://bimib.disco.unimib.it
>>>> Viale Sarca 336
>>>> I-20126 Milan (MI) ITALY
>>>>
>>>> Please check: http://cdac2018.lakecomoschool.org
>>>> Please check: http://troncopackage.org
>>>>
>>>> Please note that I am not checking my Spam-box anymore.
>>>> Please do not forward this email without asking me first (cum grano salis).
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>> --
>> Marco Antoniotti, Associate Professor		tel.	+39 - 02 64 48 79 01
>> DISCo, Università Milano Bicocca U14 2043		http://bimib.disco.unimib.it
>> Viale Sarca 336
>> I-20126 Milan (MI) ITALY
>>
>> Please check: http://cdac2018.lakecomoschool.org
>> Please check: http://troncopackage.org
>>
>> Please note that I am not checking my Spam-box anymore.
>> Please do not forward this email without asking me first (cum grano salis).
> --
> Marco Antoniotti, Associate Professor		tel.	+39 - 02 64 48 79 01
> DISCo, Università Milano Bicocca U14 2043		http://bimib.disco.unimib.it
> Viale Sarca 336
> I-20126 Milan (MI) ITALY
>
> Please check: http://cdac2018.lakecomoschool.org
> Please check: http://troncopackage.org
>
> Please note that I am not checking my Spam-box anymore.
> Please do not forward this email without asking me first (cum grano salis).
>
>
>
>
>