Metadata feature specification for MotionObservable
This is the engineering specification for the Metadata object.
Overview
In order provide introspection capabilities, each MotionObservable instance is expected to store a
small amount of meta information about itself. This information is stored in an object called
Metadata.
The metadata is currently being considered for use in visualizing the graph of connected streams in a runtime. Example code:
runtime.add(Draggable(), to: square)
timeline.timeOffset.value = CGFloat(slider.value * 0.4)
timeline.paused.value = true
let arcMove = ArcMove(duration: 0.4,
from: runtime.get(square.layer).position,
to: runtime.get(circle.layer).position,
system: coreAnimation)
arcMove.timeline = timeline
runtime.add(arcMove, to: square2)
Example output:
digraph G {
node [shape=rect]
{"translated(from:in:)(BF5FE183-A435-4FB2-9CA9-8082C3B97D14)" [label="translated(from:\nReactiveProperty<__C.CGPoint>::0x600000178c00,\nin:\nUIView::0x7f848a410900)", style=filled, fillcolor="#DB4437"]} -> {"CALayer::0x60000002d660.position" [label="CALayer::0x60000002d660.position", style=filled, fillcolor="#FFFFFF"]}
{"CALayer::0x60000002d660.position" [label="CALayer::0x60000002d660.position", style=filled, fillcolor="#0F9D58"]} -> {"translated(from:in:)(BF5FE183-A435-4FB2-9CA9-8082C3B97D14)" [label="translated(from:\nReactiveProperty<__C.CGPoint>::0x600000178c00,\nin:\nUIView::0x7f848a410900)(BF5FE183-A435-4FB2-9CA9-8082C3B97D14)", style=filled, fillcolor="#FFFFFF"]}
{"Gesture Recognizer(029F6C3D-A254-4CE9-B991-F3905AB262EE)" [label="Gesture Recognizer(:\nUIPanGestureRecognizer::0x7f848a513bc0)", style=filled, fillcolor="#FFFFFF"]} -> {"translated(from:in:)(BF5FE183-A435-4FB2-9CA9-8082C3B97D14)" [label="translated(from:\nReactiveProperty<__C.CGPoint>::0x600000178c00,\nin:\nUIView::0x7f848a410900)", style=filled, fillcolor="#DB4437"]}
{"Core Animation Path Tween(F2DC1810-419F-4077-8642-584439BF9D0D)" [label="Core Animation Path Tween(:\nMotionObservable<CoreGraphics.CGFloat>::0x600000246c00)", style=filled, fillcolor="#FFFFFF"]} -> {"CALayer::0x60000002d5e0.position" [label="CALayer::0x60000002d5e0.position", style=filled, fillcolor="#FFFFFF"]}
{"PathTween.duration(72BCFA57-F958-4519-A725-316C63792BC3)" [label="PathTween.duration", style=filled, fillcolor="#0F9D58"]} -> {"Core Animation Path Tween(F2DC1810-419F-4077-8642-584439BF9D0D)" [label="Core Animation Path Tween(F2DC1810-419F-4077-8642-584439BF9D0D):\nMotionObservable<CoreGraphics.CGFloat>::0x600000246c00", style=filled, fillcolor="#FFFFFF"]}
{"arcMove(from:to:)" [label="arcMove(from:\nMotionObservable<__C.CGPoint>::0x6000002468d0,\nto:\nMotionObservable<__C.CGPoint>::0x6000002468a0)", style=filled, fillcolor="#FFFFFF"]} -> {"Core Animation Path Tween(F2DC1810-419F-4077-8642-584439BF9D0D)" [label="Core Animation Path Tween(F2DC1810-419F-4077-8642-584439BF9D0D):\nMotionObservable<CoreGraphics.CGFloat>::0x600000246c00", style=filled, fillcolor="#FFFFFF"]}
{"CALayer::0x60000002d660.position" [label="CALayer::0x60000002d660.position", style=filled, fillcolor="#0F9D58"]} -> {"arcMove(from:to:)" [label="arcMove(from:\nMotionObservable<__C.CGPoint>::0x6000002468d0,\nto:\nMotionObservable<__C.CGPoint>::0x6000002468a0)", style=filled, fillcolor="#FFFFFF"]}
{"CALayer::0x60000002d380.position" [label="CALayer::0x60000002d380.position", style=filled, fillcolor="#0F9D58"]} -> {"arcMove(from:to:)" [label="arcMove(from:\nMotionObservable<__C.CGPoint>::0x6000002468d0,\nto:\nMotionObservable<__C.CGPoint>::0x6000002468a0)", style=filled, fillcolor="#FFFFFF"]}
{"PathTween.enabled(E1F7BB29-2A35-438C-A49A-4458161EA08E)" [label="PathTween.enabled", style=filled, fillcolor="#0F9D58"]} -> {"Core Animation Path Tween(F2DC1810-419F-4077-8642-584439BF9D0D)" [label="Core Animation Path Tween(F2DC1810-419F-4077-8642-584439BF9D0D):\nMotionObservable<CoreGraphics.CGFloat>::0x600000246c00", style=filled, fillcolor="#FFFFFF"]}
{"PathTween.state(E1F7BB29-2A35-438C-A49A-4458161EA08E)" [label="PathTween.state", style=filled, fillcolor="#0F9D58"]} -> {"Core Animation Path Tween(F2DC1810-419F-4077-8642-584439BF9D0D)" [label="Core Animation Path Tween(F2DC1810-419F-4077-8642-584439BF9D0D):\nMotionObservable<CoreGraphics.CGFloat>::0x600000246c00", style=filled, fillcolor="#FFFFFF"]}
}
MVP
Expose a Metadata type
Expose a public class type named Metadata.
public class Metadata {
}
Store name, uuid, and args
class Metadata {
public let identifier: String
public let label: String
public let args: [Any]?
private var parent: OperatorMetadata?
init(_ identifier: String, objectIdentifier: String? args: [Any]?, parent: Metadata?) {
if let objectIdentifier = objectIdentifier {
self.identifier = objectIdentifier + identifier
} else {
self.identifier = identifier
}
self.label = identifier
self.args = args
self.parent = parent
}
Expose with API
Expose a with method that creates a new OperatorMetadata with self as its parent.
class Metadata {
public func with(_ name: String, args: [Any]? = nil) -> Metadata {
return .init(name, args: args, parent: self)
}
Expose debug description API
Expose a debug description method. The output is expected to be a recursive representation of this metadata and all of its ancestral metadata.
class Metadata {
public var debugDescription: String {
}
View the issue tracking formalization of the debug description.
Store a constant metadata instance on each MotionObservable
class MotionObservable {
public let metadata: Metadata
}