Re: [scope] Scope review starts on November 26th

From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2023-11-27 08:42:12

On 11/27/23 04:50, Klemens Morgenstern via Boost wrote:
> 
> The BOOST_SCOPE_FINAL is limited to C++17 because the correct way is
> to use deduction guides, and that would be perfectly fine for me.
> However, it would be quite simple to add this functionality to C++11 like so:
> 
> struct no_one_likes_expression_templates
> {
>   template<typename Func>
>   auto operator%(Func && func) ->
> decltype(boost::scope::make_scope_exit(std::declval<Func>()))
>   {
>     return boost::scope::make_scope_exit(std::forward<Func>(func));
>   }
> };
> 
> #define BOOST_SCOPE_FINAL_11 \
>   auto BOOST_JOIN(_boost_scope_final_,
> BOOST_SCOPE_DETAIL_UNIQUE_VAR_TAG) =
> no_one_likes_expression_templates{} %

This would be a misnomer as it would create a scope_exit instead of
scope_final. You can't create a scope_final this way because it isn't
moveable, and RVO is optional in C++11.

I can provide C++11 macros a-la BOOST_SCOPE_FINAL for creating
scope_exit/fail/success (e.g. BOOST_SCOPE_EXIT/FAIL/SUCCESS_GUARD), but
I don't see a way to make BOOST_SCOPE_FINAL C++11.