Re: [boost] Another variant type (was: [peer review queue tardiness] [was Cleaning out the Boost review queue] Review Queue mem

4 Apr 2015

      AMDG

On 04/04/2015 04:33 PM, Larry Evans wrote:
...
On 04/04/2015 05:08 PM, Matt Calabrese wrote:
...
On Sat, Apr 4, 2015 at 3:06 PM, Matt Calabrese  wrote:
...
You need to use a recursive union if you are to get some constexpr support.
Well, let me rephrase, you can expand it out by preprocessor to a certain
limit and get that too, but you can't just use aligned storage. At some
point you need to hit a recursive case.
Could you please elaborate on why recursion cannot be avoided?
Variadic parameter packs can't be expanded on
class (or in this case union) members.

template
union variant_storage {
    T t;... // illegal
};

In Christ,
Steven Watanabe