Custom attributes?

Attributes are powerful way to provide meta information which can be associated with methods properties fields and etc and can be retrieved in runtime. This meta information is usually accessed through reflection and from there you can do whatever you want with that "marked" field, method, object and so forth. I will give you a short example because i feel sleepy.

Say you want to mark some fields and give the position meta information so later on you can work with it. First let's create the attribute:

 [AttributeUsage(AttributeTargets.Field)]
 public class PositionAttribute : Attribute
 {
     public readonly Vector2 position;
 
     public PositionAttribute(int x, int y)
     {
         position.x = x;
         position.y = y;
     }
 }

Now let's mark some script fields with that attribute:

 public class Node : MonoBehaviour
 {
     [Position(1, 0)]
     public object node;
 }
 

So now let's create a small custom inspector for the Node.

 using UnityEngine;
 using UnityEditor;
 using System.Reflection;
 using System;
 
 [CustomEditor(typeof(Node))]
 class NodeCustomEditor : Editor
 {
     private void OnEnable()
     {
         MonoBehaviour[] sceneActive = GameObject.FindObjectsOfType<MonoBehaviour>();
 
         foreach (MonoBehaviour mono in sceneActive)
         {
             Type monoType = mono.GetType();
 
             // Retreive the fields from the mono instance
             FieldInfo[] objectFields = monoType.GetFields(BindingFlags.Instance | BindingFlags.Public);
 
             // search all fields and find the attribute [Position]
             for (int i = 0; i < objectFields.Length; i++)
             {
                 PositionAttribute attribute = Attribute.GetCustomAttribute(objectFields[i], typeof(PositionAttribute)) as PositionAttribute;
 
                 // if we detect any attribute print out the data.
                 if (attribute != null)
                 {
                     Debug.Log(attribute.position.x); // The attribute position Y for that instance variable "1"
                     Debug.Log(attribute.position.y); // The attribute position X for that instance variable "0"
                     Debug.Log(mono.GetType()); // The type of the mono script "Node"
                     Debug.Log(objectFields[i].Name); // The name of the marked variable - "node"
                 }
             }
         }
     }
 }
 

As you see when you mark that field you get access to exclusive information which you can't get in languages that does not support reflection. From here it's up to you how you will use that data. I hope i brought some small light about the Attributes. These are extremely powerful feature and if you learn how to use them you have another tool in your box :)