From: Ian Whitlock <iw1junk@...>
Date: 2007-08-21T01:25:02+09:00
Subject: Re: How to implement a hash whose key is another hash?

unknown wrote:

> Could some explain how to use hash key which is of type hash

Perhaps studying this will explain your confusion.

require 'pp'
test ={}
k1 = {"new"=>"girl"}
k2 = {"new"=>"girl"}
test[k1]= 100
test[k2]= 200
pp k1.eql?(k2)
pp test
test ={}
test[k1]= 100
test[k1]= 200
pp test

Note that each instance of "new"=>"girl"
is a different hash object.  Basing the
key on a hash does not look like a good
idea in general.  Consider what happens
when you extend k1.

k1 = {"new"=>"girl"}
test ={}
k1["bad"]="idea"
test[k1]= 100
k1["bad"]="idea"
test[k1]= 200
pp test

Keys should be stable objects.

Ian Whitlock
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