Subject: Re: [boost] variant - off topic
From: Julien Blanc (julien.blanc_at_[hidden])
Date: 2019-04-04 11:36:57
Le mercredi 03 avril 2019 Ã 14:27 -0700, Robert Ramey via Boost a
écrit :
> I'll concede that, influenced by functional programming style, with
> a
> little experimentation with F# and propaganda from the Haskell
> community, I've become accustomed to code in the above way. Also
> I've
> become afraid to assign anything to these types. The discussion has
> made me aware of a raft of unintended consequences of doing what on
> it's
> surface seems a trivial operation. I've gotten to the point that
> assignment to a variant type, or "changing the type" of a value at
> runtime is not code smell to me. Maybe all this could be just
> eliminated if this became the accepted position.
Variants are really usefull as a container for a definite set of
messages in message queues between tasks/threads, and that usually
involves storing the last received message in a variable.
The nice thing is such variants must be variants of POD, so they don't
have the issues being discussed here.
I like the idea of simply deleting operator= : if you can't guarantee
you do something correctly, just don't do it. Optionnaly provide an
unsafe interface if it really make sense.
Regards,
Julien