Question

I’m still new to D, but an obvious missing feature (for web developers) in

http://www.digitalmars.com/d/2.0/phobos/std_json.html

is a mixin which creates JSON serialisers and deserialisers for arbitrary (nests) of structs and classes.

i.e.

struct Dog {
  string name;
  int age;
}

struct Person {
  mixin JSON;
  string name;
  int age;
  string[] favouriteFoods;
  Dog dog;
  bool retired () { return age > 65 };
}

then be able to

auto p = Person("\"name\":\"Fred\",\"age\":45,\"favouriteFoods\":[\"cheese\",\"bananas\"],\"dog\":{\"name\":\"Rover\",\"age\":7}");

p.dog.name -> "rover"
p.favouriteFoods[1] -> "bananas"
p.retired() -> false

and

p.toJSON(); -> "\"name\":\"Fred\",\"age\":45,\"favouriteFoods\":[\"cheese\",\"bananas\"],\"dog\":{\"name\":\"Rover\",\"age\":7}"

Would this be possible using the various meta programming features of D?

Thanks,

Chris.

Answer 1

Yes this is possible (I have a library which does exactly this in production right now), and D makes it pretty easy to implement using compile-time reflection. You’ll want to read up at these links:

• Traits (compile feature)
• std.traits (library)
• Template Mixins
• String Mixins