/// <summary>
/// Raises the specified event handler ensuring the event is received by each subscriber.
/// </summary>
/// <param name="handler">The event handler to raise.</param>
/// <param name="sender">The source of the event.</param>
/// <param name="e">An <see cref="PropertyChangingEventArgs"/> that contains the event data.</param>
/// <exception cref="AggregateException">The exception is thrown by at least one of the subscribers.</exception>
public static void RaiseSafe(PropertyChangingEventHandler handler, object sender, PropertyChangingEventArgs e)
{
if (handler != null)
{
List <Exception> errors = null;
Delegate[] list = handler.GetInvocationList();
for (int i = 0; i < list.Length; i++)
{
try
{
(list[i] as PropertyChangingEventHandler)(sender, e);
}
catch (Exception exception)
{
if (errors == null)
{
errors = new List <Exception>(1);
}
errors.Add(exception);
}
}
if (errors != null)
{
throw Error.Aggregate(errors.ToArray());
}
}
}
/// <summary>
/// Raises an event safely, ensuring that all handlers are called on the proper thread, and any exceptions do not prevent other handlers being called.
/// </summary>
/// <param name="handler">The event to raise.</param>
/// <param name="sender">The sender of the event.</param>
/// <param name="propertyName">The name of the property relating to this event.</param>
/// <exception cref="ArgumentNullException">Thrown if propertyName is null or an empty string.</exception>
/// <exception cref="AggregateException">Thrown if any handlers raise exceptions, with the exceptions raised captured in the <see cref="AggregateException.InnerExceptions"/> property.</exception>
public static void SafeRaise(this PropertyChangingEventHandler handler, INotifyPropertyChanging sender, string propertyName)
{
propertyName.ThrowIfNullOrEmpty(nameof(propertyName));
sender?.GetType().ValidatePropertyName(propertyName, nameof(propertyName));
if (handler is null)
{
return;
}
PropertyChangingEventArgs e = new (propertyName);
List <Exception> raisedExceptions = null;
foreach (Delegate del in handler.GetInvocationList())
{
try
{
del.DynamicInvoke(sender, e);
}
catch (TargetInvocationException ex) when(ex.InnerException is Exception)
{
if (raisedExceptions is null)
{
raisedExceptions = new List <Exception>();
}
raisedExceptions.Add(ex.InnerException);
}
}
// Check list of exceptions is either still null, or not empty.
Debug.Assert(raisedExceptions is null || raisedExceptions.Any(), "Empty list of exceptions after handling event.");
if (raisedExceptions is List <Exception> )
{
throw new AggregateException(Properties.Resources.SafeRaiseExceptionMessage, raisedExceptions);
}
}