The .NET Command Pattern, Part 2: Listing 5

The CutPresentationCommand class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace VSMCommandPatternUndo.Commands
{
    public class CutPresentationCommand : IUndoCommand
    {
        ViewModel.Presentation _cutModel;
        ViewModel.Presentation _arg;
 
        public void Undo()
        {
            _arg.Presenter = _cutModel.Presenter;
            _arg.Summary = _cutModel.Summary;
            _arg.Title = _cutModel.Title;
        }
 
        public bool CanExecute(object parameter)
        {
            return true;
        }
 
        public event EventHandler CanExecuteChanged;
 
        public void Execute(object parameter)
        {
            CommandStateManager.Instance.Executed(this);
 
            // is a not a redo?
            if (parameter != null)
            {
                _arg = parameter as ViewModel.Presentation;
            }
            
            _cutModel = new ViewModel.Presentation()
            {
                Presenter = _arg.Presenter,
                Summary = _arg.Summary,
                Title = _arg.Title
            };
 
            _arg.Presenter = String.Empty;
            _arg.Summary = String.Empty;
            _arg.Title = String.Empty;
        }
    }
}

About the Author

Eric Vogel is a Senior Software Developer for Red Cedar Solutions Group in Okemos, Michigan. He is the president of the Greater Lansing User Group for .NET. Eric enjoys learning about software architecture and craftsmanship, and is always looking for ways to create more robust and testable applications. Contact him at vogelvision@gmail.com.