gistfile1.txt

1.9.3-p125 :015 > dims['b'] = 'asdf'
 => "asdf" 
1.9.3-p125 :016 > dims['a'] = 'asassdfs'
 => "asassdfs" 
1.9.3-p125 :017 > dims.each_key {|key| puts key.object_id.to_s}
6001340
5984020
 => {"b"=>"asdf", "a"=>"asassdfs"} 
1.9.3-p125 :018 > dims['a'] = 'zomgy'
 => "zomgy" 
1.9.3-p125 :019 > dims['b'] = 'leee'
 => "leee" 
1.9.3-p125 :020 > dims.each_key {|key| puts key.object_id.to_s}
6001340
5984020
 => {"b"=>"leee", "a"=>"zomgy"} 
1.9.3-p125 :021 >