65.9K
CodeProject is changing. Read more.
Home

Following object inheritance

starIconstarIconstarIconstarIcon
emptyStarIcon
starIcon

4.29/5 (7 votes)

Jul 20, 2010

CPOL
viewsIcon

14187

Sometimes, it helps to know the complete inheritance of an object or type in order to understand what can be done with it. This Tip presents a simple C# class to access the information

Recently, when answering a Q&A about TreeView and TreeNodes, I wanted to be certain that what I was saying was absolutely correct - TreeNode does not derive from Control, and so cannot be displayed. But finding this inheritance was not simple, so I wrote a quick class to get such information. Since it may be of use to others, I present it here:
using System;
using System.Collections.Generic;
using System.Text;

namespace UtilityControls
    {
    /// <summary>
    /// Provides information on class inheritance
    /// </summary>
    public class TypeInheritance
        {
        #region Fields
        /// <summary>
        /// Internal, type of object to report
        /// </summary>
        private Type type;
        /// <summary>
        /// Internal, list of type inherited from (starting with Object)
        /// </summary>
        private List<Type> chainUpToThis = null;
        #endregion

        #region Constructors
        /// <summary>
        /// Construct a TypeInheritance object from a type
        /// </summary>
        /// <param name="t">Type to report inheritance for.</param>
        public TypeInheritance(Type t)
            {
            type = t;
            }
        /// <summary>
        /// Construct a TypeInheritance object from an object instance
        /// </summary>
        /// <param name="o">Object to report inheritance for.</param>
        public TypeInheritance(object o)
            {
            type = o.GetType();
            }
        #endregion

        #region Overrides
        /// <summary>
        /// Convert a TypeInheritance to a string.
        /// Reports the inheritance that lead to this object type,
        /// in the form "Object->..."
        /// </summary>
        /// <returns></returns>
        public override string ToString()
            {
            EnsureChainUpToAvailable();
            // Convert the chain of objects that lead up to this to a string.
            StringBuilder sb = new StringBuilder(128);
            string prefix = "";
            foreach (Type t in chainUpToThis)
                {
                sb.Append(prefix + t.Name);
                prefix = "->";
                }
            return sb.ToString();
            }
        #endregion

        #region Public Methods
        /// <summary>
        /// Return the inheritance chain as a array, starting with Object
        /// </summary>
        /// <returns>The inheritance chain as a array, starting with Object</returns>
        public Type[] ToArray()
            {
            return EnsureChainUpToAvailable().ToArray();
            }
        #endregion

        #region Private Methods
        /// <summary>
        /// Ensures the chainUpToThis list has been filled in, by creating it if it hasn't
        /// </summary>
        private List<Type> EnsureChainUpToAvailable()
            {
            if (chainUpToThis == null)
                {
                // Not done yet - create it.
                chainUpToThis = new List<Type>();
                while (type != null)
                    {
                    chainUpToThis.Insert(0, type);
                    type = type.BaseType;
                    }
                }
            return chainUpToThis;
            }
        #endregion
        }
    }