Reflect.hasField vs anon.field

Question

I'm writing a validation library for an API and I need to check anonymous data structures for required fields. Is it safe to directly reference fields (if(anon.field)...) or will this cause problems on static targets? Is there a speed difference between Reflect.hasField and direct field access?

Answer 1

Both checks have different purposes. You can do if (anon.field == null) if the field is already defined. So if the field isn't on the structure or it is uncertain (for example if you use @:optional fields in typedefs), you'll maybe get runtime errors.

Thats where Reflect.hasField comes in; it will check if it actually is defined. So if a structure has a field, you can check anything on it.

If you are targetting Javascript the Reflect.hasField does the same as Object.hasOwnProperty.

Reflect Api docs: http://api.haxe.org/Reflect.html#hasField