Bitten by Array#*

Have u tried Array#* ? Its a pretty cool way to return an array, built by concatenating the original array by n times:

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a = [1] * 2 p a # >> [1, 1] a = %w{a} * 2 p a # >> ["a", "a"]

However, u should be aware that all elements of the new array actually points to the same instance, as proven by their object_id:

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x = 'a' p x.object_id # >> 70212363949780 a = [x] * 2 p a.map(&:object_id) # >> [70212363949780, 70212363949780]

This means that:

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# Reassigning one element does not affect another a = %w{a} * 2 p a.map(&:object_id) # >> [70058328018360, 70058328018360] a[0] = a[0].sub('a','b') p a # >> ["b", "a"] p a.map(&:object_id) # >> [69915340242120, 69915340242360] # In-place manipulating one element affects another a = %w{a} * 2 p a.map(&:object_id) # >> [70058328018360, 70058328018360] a[0].sub!('a','b') p a # >> ["b", "b"] p a.map(&:object_id) # >> [70058328018360, 70058328018360]