From: Hugh Sasse Staff Elec Eng <hgs@...>
Date: 2001-06-22T23:54:49+09:00
Subject: [ruby-talk:16769] Re: uniq and "equivalence"

On Fri, 22 Jun 2001, ts wrote:

> >>>>> "H" == Hugh Sasse Staff Elec Eng <hgs@dmu.ac.uk> writes:
> 
> H> Array.uniq seems to rely on deleting multiple references to the same object.
> H> Furthermore, this test for sameness seems to be based on object.id rather
> H> than == or ===.  Most of the time this is right and proper, and also 
> H> efficient. I support my belief that this is going on with:
> 
>  Array#uniq make first an hash, then delete the elements.

is that Object#hash() or Hash.new()?  
> 
> H> When this behaviour of uniq is not not what I want, how do I change it?
> 
>  Change the hash function for the objects

   Object#hash must return a fixnum such that
   a.eql?(b) means a.hash = b.hash.  That is a pretty tall
   order for arrays of floats.  Has anyone any suggestions
   on how to proceed?
> 
> 
> Guy Decoux
> 
	Hugh
	hgs@dmu.ac.uk