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Deep copy of objects in C#

, 18 Jul 2009
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How to do a deep copy of objects using System.Reflection.

Introduction

Below you can find a short article on how to do a deep copy of objects using Reflection in C#. Please be aware that this is my first article here (even first article in the English language...)

Background

The class (called HCloner) has a DeepCopy function. It drills down the entire object fields structure (using System.Reflection) and copies it into a new location that is returned after that.

Members that are copied are fields - no need to copy properties since behind every property, there is a field. A property itself cannot hold any value.

Using the code

Let's look at the "core" code:

using System;
using System.Reflection;

namespace HAKGERSoft {

    public class HCloner {

        public static T DeepCopy<T>(T obj) {
            if(obj==null)
                throw new ArgumentNullException("Object cannot be null");
            return (T)Process(obj);
        }

        static object Process(object obj) {
            if(obj==null)
                return null;
            Type type=obj.GetType();
            if(type.IsValueType || type==typeof(string)) {
                return obj;
            }
            else if(type.IsArray) {
                Type elementType=Type.GetType(
                     type.FullName.Replace("[]",string.Empty));
                var array=obj as Array;
                Array copied=Array.CreateInstance(elementType,array.Length);
                for(int i=0; i<array.Length; i++) {
                    copied.SetValue(Process(array.GetValue(i)),i);
                }
                return Convert.ChangeType(copied,obj.GetType());
            }
            else if(type.IsClass) {
                object toret=Activator.CreateInstance(obj.GetType());
                FieldInfo[] fields=type.GetFields(BindingFlags.Public| 
                            BindingFlags.NonPublic|BindingFlags.Instance);
                foreach(FieldInfo field in fields) {
                    object fieldValue=field.GetValue(obj);
                    if(fieldValue==null)
                        continue;
                    field.SetValue(toret,Process(fieldValue));
                }
                return toret;
            }
            else
                throw new ArgumentException("Unknown type");
        }

    }
}

Using it is very simple - just call the DeepCopy function.

History

This is a very alpha-pre version of my function. I'm looking forward for some feedback from you - any issues found will be analysed and fixed (at least, I'll try).

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Hakger
Software Developer (Senior)
Poland Poland
No Biography provided

Comments and Discussions

 
GeneralNow it works with structures! [modified] PinmemberBrian Coverstone27-Apr-11 15:59 

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