encapsulated hash codes

Maciej Stachowiak mjs at apple.com
Wed Nov 4 16:50:12 PST 2009


On Nov 4, 2009, at 2:49 PM, Allen Wirfs-Brock wrote:

> A straw man proposal for  Harmony encapsulated hash codes  has been  
> posted to the Wiki athttp://wiki.ecmascript.org/doku.php?id=strawman:encapsulated_hashcodes

1) Wouldn't it be simpler to have a single Object.hash() function that  
returns a uniformly distributed number in the 0..2^32 range, and leave  
the mod operation up to code using the hash code? Making a new  
function that (essentially) encapsulates the hash operation and the  
mod does not seem to pull its weight in API complexity.

2) What about non-objects? It would be nice if strings, numbers, and  
perhaps other primitive types could hash by value rather than by  
identity, so you could reasonably mix them as hash keys with objects.

3) Security considerations: it should be recommended that the hash  
code, if computed from the address of the object, is not reversible.  
(Of course, with a copying collector you probably can't compute the  
hash code from the address).

Regards,
Maciej

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