From: Brian Candler <b.candler@...>
Date: 2011-07-14T06:18:51+09:00
Subject: Re: array overwrite question

jake kaiden wrote in post #1010461:
> CC Chen wrote in post #1010408:
>
>> If on multi-dimension array?
>>
>> I try .dup it cant work!!
>
>   what version of ruby are you using, with both 1.8.7 and 1.9.2
> Array#dup works for me...
>
> bb = [[1,2], [3,4], [5,6]]
> cc = bb.dup
>
> p cc

But of course, the subarrays in cc and the subarrays in bb are the same 
objects.

bb = [[1,2], [3,4], [5,6]]
cc = bb.dup
bb[0] << 3
p cc
# [[1, 2, 3], [3, 4], [5, 6]]

You can do the dups for the second level too yourself, or use this deep 
copy trick:

cc = Marshal.load(Marshal.dump(bb))

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