Pull up singleton behaviour.

Assets/Cryville/Common/Unity/SingletonBehaviour.cs

@@ -0,0 +1,25 @@
+using UnityEngine;
+
+namespace Cryville.Common.Unity {
+	public abstract class SingletonBehaviour<TSelf> : MonoBehaviour where TSelf : SingletonBehaviour<TSelf> {
+		static TSelf s_instance;
+		public static TSelf Instance {
+			get {
+				return s_instance;
+			}
+		}
+		bool _validInstance;
+		protected virtual void Awake() {
+			if (s_instance != null) {
+				Debug.LogErrorFormat("Duplicate singleton behaviour {0}", typeof(TSelf));
+				Destroy(gameObject);
+				return;
+			}
+			s_instance = (TSelf)this;
+			_validInstance = true;
+		}
+		protected virtual void OnDestroy() {
+			if (_validInstance) s_instance = null;
+		}
+	}
+}