I've skimmed through the language documentation and it seems that the Google Dart does not support mixins (no method bodies in interfaces, no multiple inheritance, no Ruby-like modules). Am I right about this, or is there another way to have mixin-like functionality in Dart?
I'm happy to report that the answer is now Yes!
A mixin is really just the delta between a subclass and a superclass. You can then "mix in" that delta to another class.
For example, consider this abstract class:
abstract class Persistence {
void save(String filename) {
print('saving the object as ${toJson()}');
}
void load(String filename) {
print('loading from $filename');
}
Object toJson();
}
You can then mix this into other classes, thus avoiding the pollution of the inheritance tree.
abstract class Warrior extends Object with Persistence {
fight(Warrior other) {
// ...
}
}
class Ninja extends Warrior {
Map toJson() {
return {'throwing_stars': true};
}
}
class Zombie extends Warrior {
Map toJson() {
return {'eats_brains': true};
}
}
Restrictions on mixin definitions include:
Some additional reading: