Copy Constructor Example

CopyConstructorExample.cs

using System;
using System.Collections.Generic;

namespace DeleteMeConsole
{

	public class StateChecking
	{

		public void DoTest()
		{
			Stuff stuff = new Stuff();
			stuff.Message = "Hello world";

			stuff.SubStuffs = new List<SubStuff>()
			{
				new SubStuff() { Name = "Ted", Age = 21 },
				new SubStuff() { Name = "Fred", Age = 22 }
			};

			Console.WriteLine(stuff.Message);
			Console.WriteLine(stuff.SubStuffs.Count);
			Console.WriteLine(stuff.SubStuffs[0].Name);

			SafeChange0(stuff);

			Console.WriteLine("----Safe Result ------------");
			Console.WriteLine(stuff.Message);
			Console.WriteLine(stuff.SubStuffs.Count);
			Console.WriteLine(stuff.SubStuffs[0].Name);
			
			NotSafeChange1(stuff);

			Console.WriteLine("--- Not safe 1-------------");
			Console.WriteLine(stuff.Message);
			Console.WriteLine(stuff.SubStuffs.Count);
			Console.WriteLine(stuff.SubStuffs[0].Name);
			
			AlterStuff2(stuff);

			Console.WriteLine("---Not safe 2-------------");
			Console.WriteLine(stuff.Message);
			Console.WriteLine(stuff.SubStuffs.Count);
			Console.WriteLine(stuff.SubStuffs[0].Name);
			

			AlterStuff3(stuff);

			Console.WriteLine("---Not safe 3-------------");
			Console.WriteLine(stuff.Message);
			Console.WriteLine(stuff.SubStuffs.Count);
			Console.WriteLine(stuff.SubStuffs[0].Name);


			AlterStuff4(ref stuff);

			Console.WriteLine("---Not safe 4-------------");
			Console.WriteLine(stuff.Message);
			Console.WriteLine(stuff.SubStuffs.Count);
			Console.WriteLine(stuff.SubStuffs[0].Name);

		}



		private void SafeChange0(Stuff st)
		{
			Stuff st1 = new Stuff(st); // USE COPY CONSTRUCTOR!!!!!!!
			st1.Message = "This wont change";
			st1.SubStuffs[0].Name = "My name wont change here";
			st1.SubStuffs.Add(new SubStuff() { Name = "Another change that wont affect orig object", Age = 2 });

		}

		private void NotSafeChange1(Stuff st)
		{
			var st1 = st;
			st1.Message = "NOT Safe change";
			st1.SubStuffs[0].Name = "Mr NOT Safe";
			st1.SubStuffs.Add(new SubStuff() { Name = "Omboblio", Age = 2 });

		}

		private void AlterStuff2(Stuff st)
		{
			st.Message = "Change 1";
			st.SubStuffs[0].Name = "AlterStuff1";
			st.SubStuffs.Add(new SubStuff() { Name = "Red", Age = 23 });

		}

		private static void AlterStuff3(Stuff st)
		{
			st.Message = "Change 2";
			st.SubStuffs[0].Name = "static....";
			st.SubStuffs.Add(new SubStuff() { Name = "staticboy", Age = 24 });
		}

		private void AlterStuff4(ref Stuff st)
		{
			st.Message = "Change 3";
			st.SubStuffs[0].Name = "Ref";
			st.SubStuffs.Add(new SubStuff() { Name = "reffy", Age = 25 });

		}
	}


	public class Stuff
	{
		public Stuff()
		{
		}

		public Stuff(Stuff stuff)
		{
			this.Message = stuff.Message;
			this.SubStuffs = new List<SubStuff>();
      // Lists MUST have copy constructors too!
			foreach(var val in stuff.SubStuffs)
			{
				var newSubStuff = new SubStuff(val);
				this.SubStuffs.Add(newSubStuff);
			}
			
		}


		public string Message { get; set; }

		public List<SubStuff> SubStuffs { get; set; }
	}

	public class SubStuff
	{
		public SubStuff()
		{
		}

		public SubStuff(SubStuff subStuff)
		{
			this.Age = subStuff.Age;
			this.Name = subStuff.Name;
		}


		public int Age { get; set; }

		public string Name { get; set; }
	}
}