Performer composition feature specification

Performers can emit new plans. This is a type of composition.

Composition enables the creation of higher-order plans. For example, a "Tossable" plan's performer might generate a "Draggable" and "AttachedSpring" plan. Or more simply, a "FadeIn" plan might compose out to a more general-purpose "Tween" plan.

Composition enables code reuse in the Material Motion ecosystem.

MVP

PlanEmitter API

A performer may be provided with a plan emitter object.

A PlanEmitter emits plans only for the performer's associated target.

The Performer may choose not to receive such an object.

A plan emitter declaration might look like so:

protocol PlanEmitter {
  func emitPlan(Plan)
}

A performer can be provided with a plan emitter.

Example pseudo-code protocol that a performer could conform to:

protocol ComposablePerforming {
  func set(planEmitter: PlanEmitter)
}

Pseudo-code of a performer emitting new plans:

function onGesture(gesture) {
  if gesture.state == Ended {
    planEmitter.emitPlan(Spring())
  }
}