URD

#undo redo pattern for .Net applications

this is a basic undo and redo pattern for .NET applications. in this pattern when you need an undo / redo able action you will need to warp that action in a using block. as an example if you going to change a property

using (new PropertyChange(Object, "Property", "Property changed "))
{
  Object.Property="new value";
}

now the change you made to the "Property" property of the "Object" object is added to a drop out stack and the action can undo and redo any time .

if you want an undoAble list change you can do it using same syntax

private void AddNewItem(<string>List list,string item,bool undoAble)
{
	using (undoAble?new ListChangeAddElement(list,item,"add new string to the string list"):null) //you can use a condition then you can minimize code
	{
		list.Add(item);
	}
}

Removing an Item

private void RemoveItem(list,item,bool undoAble)
{
	using(undoAble?new ListChangeRemoveElement(list,item,list.IndexOf(item)," remove "+item+" from the string list"))
	{
		list.Remove(item);
	}
}

so on.. (check the code)

benefits of this pattern

No need to change existing objects
Low Memory usage

if you wish to implement your own operation . only thing you need to do is create a class--> extend Change class and implement IUndoAble interface.

rusith/URD

URD