From: David Maciejak <david.maciejak@...>
Date: 2009-06-09T19:29:01+09:00
Subject: Re: ruby dup unexpected behaviour

Thanks for the details, in the end as you said I did the deep copy
myself. I will close the ubuntu entry.

david

On Tue, Jun 9, 2009 at 12:20 PM, Brian Candler<b.candler@pobox.com> wrote:
> David Maciejak wrote:
>> I got no answer on ubuntu entry at
>> https://bugs.launchpad.net/ubuntu/+source/ruby1.8/+bug/384265
>> so I resend it here. Does someone have any clues on this ?
>
> dup is a "shallow" copy. For a Hash, you'll get a new Hash but with the
> keys and values pointing to the same objects.
>
>>> h1 = {1=>"one", 2=>"two"}
> => {1=>"one", 2=>"two"}
>>> h2 = h1.dup
> => {1=>"one", 2=>"two"}
>>> h1.object_id
> => -605621648
>>> h2.object_id
> => -605633988           #<< the hashes are different objects
>>> h1[1].object_id
> => -605621708
>>> h2[1].object_id
> => -605621708           #<< the values are the same object
>>>
>
> If you want a deep copy, you have to do it yourself.
>
> Similarly, if you freeze a Hash, you are just freezing the Hash itself,
> not all the objects it points to.
>
>>> h1
> => {1=>"one", 2=>"two"}
>>> h1.freeze
> => {1=>"one", 2=>"two"}
>>> h1[2] << "xxx"
> => "twoxxx"
>>> h1
> => {1=>"one", 2=>"twoxxx"}
>
> If you want a "deep freeze" then you'll have to do it yourself.
>
> Your test code looks rather more convoluted than it needs to be, so you
> should be able to boil it down to a two or three line case which shows
> you what's happening.
>
> However I suggest you close the Ubuntu ticket though as 'invalid'
>
> Regards,
>
> Brian.
> --
> Posted via http://www.ruby-forum.com/.
>
>