trail-into-darkness/Packages/com.jovian.inspector-tools/Editor/Attributes/OnValueChangedAttribute.cs

using System.Reflection;
using UnityEditor;
using UnityEngine;

namespace Jovian.InspectorTools {
    public class OnValueChangedAttribute : PropertyAttribute {
        public readonly string methodName;
        public OnValueChangedAttribute(string methodName) {
            this.methodName = methodName;
        }
    }
}

#if UNITY_EDITOR
namespace Jovian.InspectorTools.Internal {

    [CustomPropertyDrawer(typeof(OnValueChangedAttribute))]
    public class OnValueChangedAttributeDrawer : PropertyDrawer {
        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label) {
            EditorGUI.BeginChangeCheck();
            EditorGUI.PropertyField(position, property, label);
            if(EditorGUI.EndChangeCheck()) {
                property.serializedObject.ApplyModifiedProperties();
                
                Object target = property.serializedObject.targetObject;
                string methodName = ((OnValueChangedAttribute)attribute).methodName;
                MethodInfo methodInfo = target.GetType().GetMethod(methodName);
                if (methodInfo != null) {
                    methodInfo.Invoke(target, null);
                }
                else {
                    Debug.LogError($"No method named '{methodName}' found on {target}", target);
                }
            }
        }
    }
}
#endif