Re: [boost] markable -- informal review request

Subject: Re: [boost] markable -- informal review request
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2016-09-21 12:35:17

On 16 Sep 2016 at 15:23, Andrzej Krzemienski wrote:

> An example use case:
> 
> typedef markable<mark_int<int, -1>> opt_int;
> 
> opt_int oi;
> opt_int o2 (2);
> assert (!oi.has_value());assert (o2.has_value());assert (o2.value() == 2);
> static_assert (sizeof(opt_int) == sizeof(int), "");

I'm not sure about the value add of this simplified optional 
implementation. What compelling use cases does it have over optional?

In my own boost::outcome::option<T>, it's just one of many 
specialisations of basic_monad<T, EC, E> and has all the advantages 
of being a basic_monad, including implicit convertibility to more 
expressive basic_monad's, monadic operators etc. It also has the same 
ridiculous optimisability that basic_monad has and typically reduces 
down to no runtime overhead (which from inspection so does your 
markable).

Yours does have likely very low impact on compile times though. Mine 
does stress the optimiser in release builds a lot.

Niall

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