2014-11-18 8:16 GMT+01:00 Matt Calabrese
On Mon, Nov 17, 2014 at 10:59 PM, Vicente J. Botet Escriba < vicente.botet@wanadoo.fr> wrote:
I will ad that I believe Dr BS don't like dynamic visitation, but here we are doing pattern matching on types, isn't it?
For a while I assumed exactly that, but he actually specifically voiced that he does not like visitation on variant and thinks of it as a hack. It's sad :/
@Matt I don't think we need to choose instead of the user. We have here two complementary interface to the same data, there is no one better than the other. Up to the user to choose the one more adapted to his needs.
I'm still not really sure I agree. I see no problem with things like Boost.MSM and Boost.Statechart both being in Boost, as while they solve many of the same problems they each have very clear advantages and disadvantages. I'm actually very much in favor of stuff like that.
On the other hand, safe_optional and optional would basically be two templates that have identical implementation with just different interfaces. If you can say objective things about one being safer, and all else is equal, then it should be THE library and the old optional should be deprecated. I don't think it's worth having two libraries when they are so similar.
This is something more than that. They have the same implementation but two different conceptual models with different trade-offs between performance, expressibility and UB-avoidance.
-- -Matt Calabrese
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