From: SpringFlowers AutumnMoon <summercoolness@...>
Date: 2007-09-18T02:03:40+09:00
Subject: Re: how to use tuple as hash key

Stefano Crocco wrote:
>
> I think that ruby uses the content of the array, not its id:
> 
> irb: 001> a=['a','b']
> ["a", "b"]
> irb: 002> h = {a => 2}
> {["a", "b"]=>2}
> irb: 003> b = %w[a b]
> ["a", "b"]
> irb: 004> h[b]
> 2
> irb: 005> a.object_id == b.object_id
> false

wow... this is deep... the reason I thought it uses the ID instead of 
the value is this:

the code:
=======================

h = {}

for i in 1..2
  for j in 1..2
    h[[i,j]] = "ha"
  end
end

p h


h2 = {}
a = [0, 0]

for i in 1..2
  for j in 1..2
    a[0] = i
    a[1] = j
    h2[a] = "ha"
  end
end

p h2

=======================
will produce:

{[1, 2]=>"ha", [2, 1]=>"ha", [1, 1]=>"ha", [2, 2]=>"ha"}
{[2, 2]=>"ha", [2, 2]=>"ha", [2, 2]=>"ha", [2, 2]=>"ha"}


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