Meta-programming detecting anonymous unions inside structs.

[rikki cattermole via Digitalmars-d-learn]

On 21/10/2016 8:55 PM, TheFlyingFiddle wrote:
> I am trying to port a serialization library I wrote in Lua some time
> ago. I've ran into a problem relating to types with anonymous unions
> inside.
>
> Given this code:
> enum Kind
> {
>    none = 0,
>    array,
>    integer,
>    floating,
> }
>
> struct Foo
> {
>    Kind type;
>    union
>    {
>        ulong  integer;
>        double floating;
>        void[] array;
>    }
>    int nonUnionField;
>    //...
> }
>
> How can I tell that "integer", "floating" and "array" are part the union
> while "nonUnionField" is not?
>
> Thanks in advance.

You're gonna have to use UDA's for that.