From: rpmohn@... (Ross Mohn)
Date: 2000-11-30T03:40:02+09:00
Subject: [ruby-talk:6645] Re: Hash with a key of nil ?

Dave@thomases.com (Dave Thomas) wrote in
<m266l6ofsd.fsf@zip.local.thomases.com>: 

>rpmohn@panix.com (Ross Mohn) writes:
>> 
>> 1) Should nil be allowed as a Hash key? This does not make sense to
>> me. 2) Maybe there should be a method defined for nil.<=> ? I think if
>> it always returned -1 it would be appropriate.
>
>Perhaps the alternative questions might be: should you always be able
>to sort a hash based on it's keys? I suspect the answer is "no".  For
>example:
>
>    h = { STDIN => 1, STDOUT => 2 }
>
>    STDIN <=> STDOUT
>    NameError: undefined method `<=>' for #<IO:0x401900a4>
>
>
>Hash keys need only provide #hash and #eql?. There's no requirement for 
><=>, so in general you can't rely on being able to sort a hash.

I guess so, but I don't know if I'm convinced yet. Maybe it's just that I'm 
not used to such a flexible language?

Thanks for re-stating the question more correctly -RPM
-- 
Ross Mohn
rpmohn@panix.com