Re: [boost] Re: copy_on_write

From: Victor A. Wagner Jr. (vawjr_at_[hidden])
Date: 2005-05-31 13:19:26

At 08:27 2005-05-31, you wrote:
>>There's a pretty nice implementation of COW objects in the Adobe Open
>>Source library (http://opensource.adobe.com).  You might take a look
>>at that.
>I saw it. Honestly, after I implemented COW myself :) Do you want to say 
>it's no sence to double existing things?
>
>>A compiler
>>that implements NRVO (Named Return Value Optimization) can return an
>>object (essentially) by const reference without any special COW
>>wrapper classes.
>Agree, this is not the best example for such a compiler. AFAIK VC++ 
>doesn't implement this optimization.
>
>>Also, some C++ Standard Library implementations use
>>a reference-counted std::string implementation, so this extra effort
>>would be wasted.
>STLport and Dinkumware (I suppose most widely used) doesn't belong to that 
>implementations. That's why personally I require COW-wrapper.

IIRC there was an article written with the title something like 
"Pessimization" which discussed the drawbacks to COW in a 
multi-threading/tasking world.  It's one of the reasons that quit using 
that paradigm.

I think you need to re-evaluate your "requirement"

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Victor A. Wagner Jr.      http://rudbek.com
The five most dangerous words in the English language:
               "There oughta be a law"