Re: [boost] [submission] STL-compliant containers with copy-on-write

Subject: Re: [boost] [submission] STL-compliant containers with copy-on-write
From: Ilya Sokolov (ilyasokol_at_[hidden])
Date: 2011-04-01 01:07:45

On Fri, 01 Apr 2011 03:07:23 +0600, Jeremy Maitin-Shepard  
<jeremy_at_[hidden]> wrote:

> On 03/31/2011 01:48 PM, Alexandr Sterligov wrote:
>> Yes, sorry... I will be more careful with calling anything  
>> STL-compliant. It
>> is only STL-like.
>
> It seems that using a generic COW wrapper might be more suitable.  
> Internally it would maintain a pointer to a reference-counted instance  
> of the base type.  It would provide a method for getting a const  
> reference to the type (e.g. get(), operator*() and operator->()), and  
> also a method for obtaining a non-const reference to a unique copy of  
> the type (e.g. get_unique()), which would take care of copying if the  
> reference count is greater than 1.
>
> I believe this interface is better than a specialized type that tries to  
> mimic the interface of a particular container because generally if there  
> is a need to mutate the type, it will be done by a series of possibly  
> many mutating operations on the type/iterations, and it is inefficient  
> to check if there is a need to copy e.g. on each iterator dereference or  
> on each invocation of operator[].
>
> It also avoids the need to create the specialized types in the first  
> place; a single quite simple wrapper type will solve the problem for all  
> types.

See http://stlab.adobe.com/classadobe_1_1version__1_1_1copy__on__write.html