Boost logo

Boost :

From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2019-10-22 22:00:58

On Tue, Oct 22, 2019 at 2:53 PM Gavin Lambert via Boost <
boost_at_[hidden]> wrote:

> On 23/10/2019 05:25, Vinnie Falco wrote:
> >> So I'm curious why it should be different here. Does the doc goes into
> that already?
> >
> > `json::value` is not `variant<...>` for the same reason that
> > `string_view` is not `std::pair<char const*, std::size_t>`.
> That's a good reason for not inheriting from it.
> It's not a good reason for not using it as a private member, to avoid
> reimplementing the variant-storage concept.
> (Though there may be other good reasons for that.)

There are always two kinds of dependencies, logical and physical.
Logically, you use something as a private member, you're ok, but physically
you're still dependent on it, and that may be a problem. Further,
std::variant may be problematic for portability, and it may or may not be
as efficient as something hand-written specifically for the purpose.
Consider that if performance is critical, you don't want to deal with "I
changed my compiler and now your JSON parser runs 2x slower".

Boost list run by bdawes at, gregod at, cpdaniel at, john at