Generate TypeAdapters for sealed classes

[akshdeep-singh]

Is your feature request related to a problem? Please describe.
Add support for sealed class adapters

Describe the solution you'd like
Adapters for sealed classes are generated automatically

Describe alternatives you've considered

Version

• Platform: iOS, Android, Mac, Windows, Linux, Web
• Flutter version: [e.g. 1.5.4]
• Hive version: [e.g. 0.5.0]

[Rexios80]

What exactly happens if you try to generate adapters for sealed classes right now?

[akshdeep-singh]

Let's say I have a sealed class like this:

sealed class Animal {}
final class Dog extends Animal {}
final class Cat extends Animal {}

This is what is generated:

class AnimalAdapter extends TypeAdapter<Animal> {
  @override
  final typeId = 10;

  @override
  Animal read(BinaryReader reader) {
    reader.readByte();
    return Animal();
  }

  @override
  void write(BinaryWriter writer, Animal obj) {
    writer.writeByte(0);
  }

  @override
  int get hashCode => typeId.hashCode;

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is AnimalAdapter &&
          runtimeType == other.runtimeType &&
          typeId == other.typeId;
}

which is wrong because Abstract classes can't be instantiated.

[Rexios80]

You would have to generate an adapter for each sub class. This has nothing to do with sealed classes.

[akshdeep-singh]

Can you give an example where the box is of the base class type? or do you mean I have to create custom type adapter?

[Rexios80]

What happens currently if you use a box of the base type?