Re: [boost] Boost.Fiber mini-review September 4-13

Subject: Re: [boost] Boost.Fiber mini-review September 4-13
From: Agustín K-ballo Bergé (kaballo86_at_[hidden])
Date: 2015-09-04 15:32:39

On 9/4/2015 2:50 PM, Oliver Kowalke wrote:
> 2015-09-04 19:28 GMT+02:00 Agustín K-ballo Bergé <kaballo86_at_[hidden]>:
>
>> Nod, just like my analysis above says. So would you be willing to take
>> patches for C++11 support?
>>
>
> if the code remains readable, yes

Supporting `index_sequence` is easy, that's a library feature that can 
be implemented in C++11. The implementation I linked earlier is even 
better at compile times than some of those shipped by standard library 
implementations (but not as good as it could be).

> I encountered that emulating move capture is not trivial, but maybe you
> have a nifty solution

Emulating move capture is not that simple, consider this initial 
implementation:

[=,fn=std::forward< Fn >( fn),tpl=std::make_tuple( std::forward< Args >( 
args) ...)] () mutable -> decltype( auto) {
     try {
         BOOST_ASSERT( is_running() );
         detail::invoke_helper( std::move( fn), std::move( tpl) );
         BOOST_ASSERT( is_running() );
     } catch( fiber_interrupted const&) {
         except_ = std::current_exception();
     } catch( ... ) {
         std::terminate();
     }
});

A C++11 compatible one would instead do:

std::bind([](
     typename std::decay<Fn>::type& fn,
     decltype(std::make_tuple( std::forward< Args >( args)))& tpl
) -> void {
     try {
         BOOST_ASSERT( is_running() );
         detail::invoke_helper( std::move( fn), std::move( tpl) );
         BOOST_ASSERT( is_running() );
     } catch( fiber_interrupted const&) {
         except_ = std::current_exception();
     } catch( ... ) {
         std::terminate();
     }
}, std::forward< Fn >( fn), std::make_tuple( std::forward< Args >( args) 
...)); // I assume there's a `this` involved here as well

Incidentally, try to avoid using `auto/decltype(auto)` on function 
templates (specially when the return type is as simple as `void`), as 
instantiation is required for them even for innocuous things like using 
`decltype` on them.

Regards,
-- 
Agustín K-ballo Bergé.-
http://talesofcpp.fusionfenix.com