Flutter: magic, particle Generator

main.dart

/// A function which returns [Particle] when called
typedef ParticleProvider = Particle Function(int i);

/// A [CompositeParticle] which allows to use [ParticleProvider] 
/// generator functions as source for children particles
/// 
/// ```dart
/// // 10 plain fading circles
/// ParticleGenerator(10, (i) => FadingCircle());
/// 
/// // 10 randomly sized fading circles
/// ParticleGenerator(10, (i) => FadingCircle(radius: Randoms.rnd.nextDouble() * 10));
/// 
/// // 5 small and 5 large fading circles
/// ParticleGenerator(10, (i) => FadingCircle(radius: i < 5 ? 10 : 20));
/// ```
class ParticleGenerator extends Particle with CompositeParticle {
  List<Particle> children;

  ParticleGenerator(
    int count,
    ParticleProvider generator,
  ) {
    this.children = List<Particle>.generate(count, generator);
  }
}