Re: [boost] New Library Proposal: dual_state

From: Andrey Melnikov (melnikov_at_[hidden])
Date: 2005-07-16 12:12:11

Calum Grant wrote:
> Andrey Melnikov wrote:
>>
>>I hate extra dynamic memory allocation even more than I hate extra 
>>copies, because the former cannot be optimized out and usually takes 
>>more time than 10 extra copies. Well, pool allocators help a lot 
>>sometimes, but it's an optimization technology.
>>
>>I like Boost.Optional because it offers a good way to deal with 
>>optonality without any extra pointers, memory allocations, special 
>>"NULL" values or construction or copy operations . I think it's way 
>>different from the concept of smart pointers.
> 
> 
> But we're talking about private implementation.  From a semantic
> perspective, Optional behaves like a smart pointer with a "copy on
> assign" policy.  Perhaps there would be fewer howls of disapproval if I
> called it a smart container, not a smart pointer.

It's just a terminology question. Boost.Optional isn't a "pointer". It 
isn't an enhanced C pointer, it isn't used like a pointer, it doesn't 
use pointers internally. It can be "dereferenced", but it's just a 
syntactic feature.

Also it isn't a container in STL sense. It doesn't provides range 
interface, iterators etc.

I would call Boost.Optional a proxy.

> 
> If an implementation improves a smart container/pointer in this
> circumstance then that's fanstastic.

I don't understand you here.

Andrey