PlaySession

Remarks

The seam [11](../../../docs/plan/11-editor.md) § "Play mode runs a system graph" left open. An EngineLoop's default registration is behaviours, coroutines and transforms; every other system a game runs — physics, audio, navigation, the render extractions — is added by that game's own OnInitialise against a host service. There is no AddStandardSystems, so the editor cannot reproduce a game's frame by scheduling harder. What it *can* do is let whoever owns a service add the systems that need it, which is what an IPlaySystems contribution is — and then let a project's own [GameSystem] declarations be built out of what those contributions provided, which is what IServiceProvider on this class is for.

⚠ Per session, and that is the whole reason this object exists rather than a service in PluginServices. A PhysicsScene is created when Play is pressed and destroyed when Stop is, because a body that simulates while somebody drags a gizmo is a scene that edits itself — and because the entities its bodies live on must be *inside* the snapshot's restore, so that stopping takes them away with everything else a session made. Publishing that scene into a bag which has no removal would hand every later reader a handle to a disposed native world.

⚠ Owns``1 and OnStop run before the world is restored. PlayModeController.Stop releases the session while its entities are still alive, so a contributor destroying bodies has something to destroy — and so the leak comparison that follows measures what the session leaked rather than what it had not got round to freeing yet.

Fields and properties (3)

• public EngineLoop Loop

  The graph this session steps.

• public World World

  The world it runs over, which is the one being edited.

• public IReadOnlyList<string> Running

  What the contributors said they added, in the order they said it.

Methods (7)

• public PlaySession(EngineLoop loop, World world)

  Builds a session over a loop.

• public void Runs(string name)

  Says what was added, for the report the session opens with.

• public T Owns<T>(T resource) where T : IDisposable

  Hands something to the session to dispose when the session ends.

• public void OnStop(Action action)

  Registers something to run when the session ends.

• public void Provide<T>(T service) where T : class

  Offers a service to the contributors that have not attached yet.

• public void ProvideValue<T>(T value) where T : struct

  Offers a value to the contributors that have not attached yet.

• public bool TryGet<T>(out T? service) where T : class

  Asks for a service an earlier contribution provided.

Used by (23)

• AnimationWiringTestsVixen.Editor.App.Tests
• ConsumerVixen.Editor.SceneView.Tests
• DeclaredConsumerVixen.Editor.SceneView.Tests
• DeclaredProviderVixen.Editor.SceneView.Tests
• EditorApplicationVixen.Editor.App
• IPlaySystemsVixen.Editor.SceneView
• LyingProviderVixen.Editor.SceneView.Tests
• NudgeVixen.Editor.SceneView.Tests
• PlayAnimationVixen.Editor.App
• PlayDeclaredSystemsTestsVixen.Editor.SceneView.Tests
• PlayDiagnosticsVixen.Editor.App
• PlayModeControllerVixen.Editor.SceneView
• PlayOverlayTestsVixen.Editor.App.Tests
• PlayPhysicsVixen.Editor.App
• PlaySystemOrderVixen.Editor.SceneView
• PlaySystemsTestsVixen.Editor.SceneView.Tests
• PlayTerrainCollidersVixen.Editor.Terrain.Physics
• ProviderVixen.Editor.SceneView.Tests
• RefusesVixen.Editor.SceneView.Tests
• SpawningProviderVixen.Editor.SceneView.Tests
• SuppliesAQuotaVixen.Editor.SceneView.Tests
• SuppliesAWarehouseVixen.Editor.SceneView.Tests
• TerrainSessionTestsVixen.Editor.App.Tests