From: Mike Stephens <rubfor@...>
Date: 2011-01-18T12:05:51+09:00
Subject: Re: Calling by Reference - Two Questions

Well, that is bizarre.

In 1.8.6 I get:

def myswap(arr)
  [arr[1], arr[0]]
end

def myswap!(arr)
  arr[0], arr[1] = arr[1], arr[0]
end

def myswap2!(arr)
  arr[0], arr[1] = arr[1], arr[0]
  arr
end

a = [2, 5]
puts " start #{a} #{a.object_id} " #start 25 27431650

myswap a # => [5,2] (new object)
puts " myswap #{a} #{a.object_id} " myswap 25 27431650

myswap! a # => [5,2] (a now is changed; note that the returned array
isnot a)
puts " myswap! #{a} #{a.object_id} " myswap! 52 27431650

myswap2! a
puts " myswap2! #{a} #{a.object_id} " myswap2! 25 27431650


I have no idea why myswap! works and myswap2! doesn't.

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