CrowdControl/Assets/Feel/MMTools/Tools/MMExtensions/MMGameObjectExtensions.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using UnityEngine.UI;

namespace MoreMountains.Tools
{
	/// <summary>
	/// Game object extensions
	/// </summary>
	public static class GameObjectExtensions
	{
		static List<Component> m_ComponentCache = new List<Component>();

		/// <summary>
		/// Grabs a component without allocating memory uselessly
		/// </summary>
		/// <param name="this"></param>
		/// <param name="componentType"></param>
		/// <returns></returns>
		public static Component MMGetComponentNoAlloc(this GameObject @this, System.Type componentType)
		{
			@this.GetComponents(componentType, m_ComponentCache);
			Component component = m_ComponentCache.Count > 0 ? m_ComponentCache[0] : null;
			m_ComponentCache.Clear();
			return component;
		}

		/// <summary>
		/// Grabs a component without allocating memory uselessly
		/// </summary>
		/// <typeparam name="T"></typeparam>
		/// <param name="this"></param>
		/// <returns></returns>
		public static T MMGetComponentNoAlloc<T>(this GameObject @this) where T : Component
		{
			@this.GetComponents(typeof(T), m_ComponentCache);
			Component component = m_ComponentCache.Count > 0 ? m_ComponentCache[0] : null;
			m_ComponentCache.Clear();
			return component as T;
		}

		/// <summary>
		/// Grabs a component on the object, or on its children objects, or on a parent, or adds it to the object if none were found
		/// </summary>
		/// <param name="this"></param>
		/// <typeparam name="T"></typeparam>
		/// <returns></returns>
		public static T MMGetComponentAroundOrAdd<T>(this GameObject @this) where T : Component
		{
			T component = @this.GetComponentInChildren<T>(true);
			if (component == null)
			{
				component = @this.GetComponentInParent<T>();    
			}
			if (component == null)
			{
				component = @this.AddComponent<T>();    
			}
			return component;
		}
	}
}