From: Mark Brassard <markbrassard@...>
Date: 2009-09-11T03:48:20+09:00
Subject: Re: hash value inconsistencies

Tim Pease wrote:
> ruby -e "puts 'test'.hash"
> 
> Should this output the same integer value on all platforms where Ruby
> can run?
> 
> * Windows
> ruby --version    #=> ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-
> mswin32]
> ruby -e "puts 'test'.hash"   #=> -914358341
> 
> * Mac 10.5
> ruby --version    #=> ruby 1.8.6 (2007-03-13 patchlevel 0) [i686-
> darwin8.10.3]
> ruby -e "puts 'test'.hash"    #=> -914358341
> 
> * Linux 2.6 Kernel
> ruby --version    #=> ruby 1.8.6 (2007-06-07 patchlevel 36) [x86_64-
> linux]
> ruby -e "puts 'test'.hash"    #=> 1233125307
> 
> ruby --version    #=> ruby 1.8.5 (2006-12-04 patchlevel 2) [x86_64-
> linux]
> ruby -e "puts 'test'.hash"    #=> 1233125307
> 
> 
> It appears not!  So, any suggestions on generating an ID number for an
> object that is unique yet consistent across different platforms?  I'd
> like to have some method that I could call on an object that would
> return a reproducible value that would uniquely identify that object.
> 
> Thoughts?
> 
> TwP


The problem is that some of your test machines are 64-bit and some are 
32-bit. I Ran the same tests on some Macs running Snow Leopard(64-bit) 
and Leopard(32-bit) and Linux (64-bit) and Linux (32-bit) and all 
results were consistent over OSes with the same bits.
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