Re: [boost] expected/result/etc

Subject: Re: [boost] expected/result/etc
From: Domagoj Saric (dsaritz_at_[hidden])
Date: 2016-02-04 17:20:14

On 28.1.2016. 13:36, Niall Douglas wrote:
> The way I've done it is to define a custom error code category per
> category of error throwing thing, thereby naturally extending C++
> 11/Boost error codes. It may seem like an awful lot of boilerplate
> when you just want an enum really, but trust me that it is worth the
> effort - you get stuff like free error_code to exception throw to
> error_code conversions (you specifically need that machinery to
> return error codes from constructors)...

You don't need necessarily need to use std::error_code to 'return' 
errors from constructors...+ this practice is IMO a bit ugly (i.e.
http://www.gotw.ca/publications/mill13.htm). In C++11 and later I think 
this can be solved more cleanly with static noexcept factory functions 
(which return outcomes/fallible_results/whatever), a move constructor 
and one variadic template constructor which forwards its arguments to 
the factory function(s) (so this pair of constructors handles any number 
of factory overloads) and forwards the result/return of the factory 
function to the move constructor...So, if you want noexcept construction 
you use a factory function or a constructor otherwise...

-- 
"What Huxley teaches is that in the age of advanced technology, 
spiritual devastation is more likely to come from an enemy with a 
smiling face than from one whose countenance exudes suspicion and hate."
Neil Postman