Subject: Re: [boost] [review] Review of Outcome (starts Fri-19-May)
From: Andrzej Krzemienski (akrzemi1_at_[hidden])
Date: 2017-05-18 20:51:45
2017-05-18 16:52 GMT+02:00 Niall Douglas via Boost <boost_at_[hidden]>:
> > It's interesting. Only after Peter's explanation I am able to see the
> > usefulness of outcome<>, at least this part of the interface. It looks
> like
> > you - Peter - have the understanding of Niall's intentions. And I am
> > clearly lacking them. I would not be able to figure out this use case
> from
> > the tutorials of the reference.
> >
> > This gives me the impression that the library has a big potential, but it
> > may not succeed because of the failure to explain its power to potential
> > users.
>
> This has been a persistent problem over the past year.
>
> Once you've been using these things in your own code for a bit, for
> especially low level systems libraries you'd never willingly go back.
> The difference is very similar (to me at least) to that feeling you have
> when you must go back to writing C++ 98 without Boost after you've been
> using C++ 14 for a quite a while.
>
> All that said, 60-70% of C++ would see no benefit to using Outcome nor
> Expected. Such code is always better off using only C++ exceptions.
>
> > It would really be helpful to see a section in the docs with a number of
> > examples simple as the ones above, explaining different use cases.
>
> I am hesitant to add even more length to the existing documentation.
> It's already long enough to put people off.
>
> A refactoring and shortening of the current length would be much more
> desirable.
>
> > I am
> > still missing how the tribool logic can be used: in if-statements?
> >
> > ```
> > if (o1 || o2) ... // is that it?
> > ```
>
> Outcome provides both binary and ternary conversion operators.
> Unqualified usage in an if statement will use the binary edition which
> is true iff state is valued, false otherwise. If you compare an outcome
> to a tribool, you'll use the ternary edition, there you can test against
> true, false, and other.
>
> If ternary logic suits your use case, using it can make your code much
> clearer.
Can you show me the case that ternary logic woud suit and make the code
much cleaner?