Re: [boost] [outcome] outcome without empty state?

Subject: Re: [boost] [outcome] outcome without empty state?
From: Gavin Lambert (gavinl_at_[hidden])
Date: 2017-05-24 23:24:44

On 25/05/2017 08:44, Jonathan Müller wrote:
> What about providing no default constructor? There are two valid choices so
> why surprise half the users?
> 
> Yes, it makes it a bit harder to use in arrays, but how often would it need
> to be stored in arrays anyways.

Surprisingly often, if it ends up being used to represent the collection 
of results from methods executed in sequence or in parallel (although 
perhaps future<> is more suited to that task, since they're more likely 
to be asynchronous).

Speaking of which, it seems like outcome<> is essentially just trying to 
be a not-asynchronous version of future<> that can elect to transport a 
std::error_code instead of a std::exception_ptr.  So most likely its 
design decisions should be inspired mostly from that (and any pain 
points that people have experienced with that interface).  Perhaps it 
even should be designed in such a way that std::future itself could be 
based on it?