From: Rajinder Yadav <devguy.ca@...>
Date: 2009-10-15T10:39:54+09:00
Subject: Re: deep cloning, how?

Robert Klemme wrote:
> On 14.10.2009 19:03, Caleb Clausen wrote:
> 
>> The documentation of Object#dup seems to suggest that subclasses
>> should not override dup, preferring to override clone instead.
> 
> Where do you take that from?  In the docs referenced below I cannot find 
> anything like that.  The only indication I can see is that #dup uses 
> #initialize_copy and we should probably override that instead of #dup 
> itself.
> 
>> I'm not
>> sure why this should be or why overriding dup would be bad. But
>> anyway, I would suggest this:
>>
>> def deep_clone
>>   copy=clone
>>   copy.name=@name.clone
>>   copy
>> end
>>
>> just so you can keep the existing semantics of clone as a shallow copy.
>>
>> I'm really not sure why there are 2 methods to create shallow copies
>> in ruby and what all the differences are supposed to be. Other than
>> not overriding dup(?), the only other difference between them that I
>> can discover is that clone copies the metaclass of the object, whereas
>> dup reverts the copy's metaclass to being just its class. I've been
>> wondering about the difference between the 2 recently; I hope someone
>> out there can provide some enlightenment on why there are 2 and what
>> the differences are.
> 
> There are more differences namely in the area of frozen and tainted state.
> 
> http://www.ruby-doc.org/core/classes/Object.html#M000351
> http://www.ruby-doc.org/core/classes/Object.html#M000352
> 

Thanks for the links and solutions Robert. This one got some good replies.

> Kind regards
> 
> robert
> 


-- 
Kind Regards,
Rajinder Yadav

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