Another serialization topic, reduced scope

[Tobias Pankrath]

On Saturday, 7 December 2019 at 18:53:51 UTC, Jesse Phillips 
wrote:
> @optional

If we look at e.g. json-schema.org or openapis.org they seem to 
have optional by default. So we should at least consider this as 
well, e.g.

1. have optional by default and introduce @required
2. make it configurable on the containing struct / class

enum IfMissing {
     setDefault,
     keep
}

@missing(IfMissing.SetDefault)
struct S
{
     // all fields by default optional due to @missing
     @required
     int x;
     int a = 4; // set to 0 if not provided during deserialization
}

3. something else ..