по первой ссылке
| Цитата | | BookViewModel унаследован от класса ViewModelBase, который заботливо сгенерил нам MVVM Toolkit. ViewModelBase же, в свою очередь, реализует интерфейс INotifyPropertyChanged и содержит функцию OnPropertyChanged. Все это нужно для того, чтобы всегда можно было вызвать событие "изменилось такое-то поле". |
пример реализации
| Код | /// <summary>
/// Base class for all ViewModel classes in the application. It provides support for property change notifications
/// and has a DisplayName property. This class is abstract.
/// </summary>
public abstract class ViewModelBase : INotifyPropertyChanged, IDisposable
{
private readonly Dispatcher _dispatcher;
/// <summary>
/// Returns the dispatcher object to perform operations on UI thread.
/// </summary>
protected Dispatcher Dispatcher
{
get { return _dispatcher; }
}
/// <summary>
/// Returns the user-friendly name of this object. Child classes can set this property to a new value,
/// or override it to determine the value on-demand.
/// </summary>
public virtual string DisplayName { get; protected set; }
protected ViewModelBase()
{
if (System.Windows.Application.Current != null)
{
_dispatcher = System.Windows.Application.Current.Dispatcher;
}
else
{
//this is useful for unit tests where there is no application running
_dispatcher = Dispatcher.CurrentDispatcher;
}
}
#region INotifyPropertyChanged Members
/// <summary>
/// Raised when a property on this object has a new value.
/// </summary>
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
/// Raises this object's PropertyChanged event.
/// </summary>
/// <param name="propertyName">The property that has a new value.</param>
protected virtual void OnPropertyChanged(string propertyName)
{
VerifyPropertyName(propertyName);
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
var e = new PropertyChangedEventArgs(propertyName);
handler(this, e);
}
}
#endregion // INotifyPropertyChanged Members
#region IDisposable Members
/// <summary>
/// Invoked when this object is being removed from the application
/// and will be subject to garbage collection.
/// </summary>
public void Dispose()
{
OnDispose();
}
/// <summary>
/// Child classes can override this method to perform
/// clean-up logic, such as removing event handlers.
/// </summary>
protected virtual void OnDispose()
{
}
#endregion // IDisposable Members
} |
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