Re: [boost] Proposed new RAII Library

Subject: Re: [boost] Proposed new RAII Library
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2012-09-14 19:19:52

Le 15/09/12 00:28, Lorenzo Caminiti a écrit :
> On Fri, Sep 14, 2012 at 1:08 PM, Vicente J. Botet Escriba
> <vicente.botet_at_[hidden]> wrote:
>> So resuming, the boost::scope_guard (without a dismiss state) is a
>> convenient abstraction for c++11 compilers supporting lambdas, and
>> Boost.ScopeExit reflects the same abstraction for C++03.
>>
>> I will be for an extension of Boost.ScopeExit that provides a non-macro
>> interface, like the one of the preceding scope_guard, for the people that
>> don't need to make their code portable to non c++11 compilers. I will name
>> it however scoped_exit.
>>
>> Extracted from the Boost.ScopeExit
>>
>>
>> struct  scope_exit  {
>>      scope_exit(std::function<void  (void)>  f)  :  f_(f)  {}
>>      ~scope_exit(void)  {  f_();  }
>> private:
>>      std::function<void  (void)>  f_;
>> };
> void world::add_person(person const& a_person) {
>       bool commit = false;
>
>      persons_.push_back(a_person);
>      scope_exit on_exit1([&commit, this](void) { // Use C++11 lambda.
>          if(!commit) persons_.pop_back(); // `persons_` via captured `this`.
>      });
>
>      // ...
>
>      commit = true;
> }
>
> Sure if there's enough interest I can move this scope_exit class from
> the examples into the Scope Exit lib itself when #ifndef
> BOOST_NO_LAMBDAS.
>
> My _personal_ opinion is that such a boost::scope_exit class is so
> trivial that programmers can just program it themselves, but that's
> just my opinion and I'm happy to add such a feature (or better to move
> it into the lib from the examples) if Boosters want it. No review
> should be needed, I can just post the (trivial) changes on this ML and
> confirm them with Alexander Nasonov.
Lorenzo, thanks for volunteering but the design and implementation is 
far more complex than the extract from the doc. If we want it to be 
efficient, it shouldn't use boost.function, 
boost/multi_index/detail/scope_guard.hpp should be a good staring point.

Best,
Vicente