My last mail didn't have many answers, maybe this one makes people think and give ideas...
-------------------- RFC: Hashing PMC's -------------------- Current PerlHash implementation accepts PMC's as keys, as long as they can be transformed into Strings. While this can be enough for many cases, having a very complex PMC as key will lead to a recursive String generation. A hash table implementation can be easily done from any type to any other type as long as we can compare that type, and we can generate some hash from it. For strings, there are a very wide range of hash functions (from simple ones to more complicated ones, like MD5). So, if we want a hash to accept PMC as keys, we have to compare and hash them. Comparing is already possible as long as PMC classes implement the correspondent vtable method. Finally, we need to hash PMC's. While I don't know what hash function we should use, I can write some goals for it: 1) Different PMC types should lead to different hash values; 2) Hash values should be calculated recursively, within the PMC nested datatypes; 3) Be quick; Please, send ideas replying to this e-mail (directly to me or to the list). Thanks, Alberto -- Alberto Manuel B. Simoes Departamento de Informática - Universidade do Minho http://alfarrabio.di.uminho.pt/~albie - http://numexp.sf.net
