Decision Guide¶

“I need to…” → Use this pattern¶

Need	Pattern
Remappable / undoable input	Command
Thousands of identical-looking objects	Flyweight
Decouple systems with events	Observer
Spawn many pre-configured objects cheaply	Prototype
One instance of a manager	Singleton
Entity with mutually exclusive modes	State
Entity spanning multiple domains (physics, render, audio)	Component
Buffer or coalesce events across frames	Event Queue
Swap service implementations	Service Locator
Add enemy types without new subclasses	Type Object
Many ability subclasses with safe, consistent cleanup	Subclass Sandbox
Designer-editable behavior without recompile	Bytecode
Frame-rate-independent updates	Game Loop
Self-contained per-entity per-frame logic	Update Method
Read and write same state in one frame	Double Buffer
Cache-friendly bulk data updates	Data Locality
Avoid recomputing unchanged derived values	Dirty Flag
High-frequency spawn/destroy without allocation cost	Object Pool
Fast proximity / range queries	Spatial Partition

These patterns are already implemented in the engine — reach for the built-in before writing your own.

Pattern	Built-in Acron system
Observer	`messenger` + `DirectObject.accept()`
State	`direct.fsm.FSM.FSM`
Game Loop	`ShowBase.run()` + `taskMgr`
Command (sequences)	`Sequence` + `FunctionInterval`
Flyweight	`ModelPool` + `NodePath.instanceTo()`
Object Pool (particles)	`ParticleEffect`
Service Locator	`base`, `taskMgr`, `messenger`, `loader`
Double Buffer (rendering)	Acron renderer (automatic)