/// <summary>
/// Notifies listerners the calling property is being changed and modifies and excecutes given action.
///
/// <para>Should be called in all bindable properties. Only notifies listeners when the property action was successful,
/// unless otherwise stated using the <paramref name="overrideNotification"/> parameter.</para>
/// </summary>
/// <typeparam name="T">The property type.</typeparam>
/// <param name="setPropertyAction">Action to be taken upon setting the property given property setter value, in the form of a
/// function delegate, returning true if the action was successful.</param>
/// <param name="overrideNotification">Detemines when listeners are notifies.
/// By default, listeners are only notified when the property action is successful.</param>
/// <param name="propertyName">Name of the property, as expected by listeners. This
/// value is automatically provided by <see cref="CallerMemberNameAttribute"/>, if not explicity provided.</param>
/// <returns>True if the property action was successful, otherwise false.</returns>
protected bool SetProperty <T>(Func <bool> setPropertyAction,
NotifyListeners overrideNotification = NotifyListeners.Default,
[CallerMemberName] string propertyName = null,
IEnumerable <string> additionalNames = null)
{
bool actionResult;
if (ShouldNotify(setPropertyAction, out actionResult, overrideNotification: overrideNotification))
{
NotifyPropertyChanged(propertyName, additionalNames);
}
return(actionResult);
}
private bool ShouldNotify(Func <bool> evaluationFunction,
out bool functionResult,
NotifyListeners overrideNotification = NotifyListeners.Default)
{
functionResult = evaluationFunction();
if (functionResult)
{
if (overrideNotification != NotifyListeners.Never)
{
return(true);
}
return(false);
}
if (overrideNotification == NotifyListeners.Always)
{
return(true);
}
return(false);
}
/// <summary>
/// Notifies listerners the calling property is being changed and modifies and sets backing field.
///
/// <para>Should be called in all bindable properties. Only notifies listeners when the property did not already equal the new value,
/// unless otherwise stated using the <paramref name="overrideNotification"/> parameter.</para>
/// </summary>
/// <typeparam name="T">The property type.</typeparam>
/// <param name="propertyRef">Reference to a property backing field.</param>
/// <param name="value">New value for the property.</param>
/// <param name="overrideNotification">Detemines when listeners are notifies.
/// By default, listeners are only notified when the property value is indeed changed.</param>
/// <param name="propertyName">Name of the property, as expected by listeners. This
/// value is automatically provided by <see cref="CallerMemberNameAttribute"/>, if not explicity provided.</param>
/// <param name="additionalNames">Names of addtional properties that will also notify listeners of change.</param>
/// <returns>False if the property need not be changed, otherwise true.</returns>
protected bool SetProperty <T>(ref T propertyRef, T value,
NotifyListeners overrideNotification = NotifyListeners.Default, [CallerMemberName] string propertyName = null,
IEnumerable <string> additionalNames = null)
{
var tempField = propertyRef;
Func <bool> CheckNotEqual = () => !(object.Equals(tempField, value));
bool areNotEqual;
bool notify = ShouldNotify(CheckNotEqual, out areNotEqual, overrideNotification: overrideNotification);
if (areNotEqual)
{
propertyRef = value; //TEST valuechangedonevent: Check ref value mutation before notify
}
if (notify)
{
NotifyPropertyChanged(propertyName, additionalNames);
}
return(areNotEqual);
}
public void SetProperty_ActionOverrideNotify_ListenersNotified(bool actionSuccess, NotifyListeners overrideNotification)
{
bool isNotifiedExpected;
switch (overrideNotification)
{
case NotifyListeners.Always:
isNotifiedExpected = true;
break;
case NotifyListeners.Never:
isNotifiedExpected = false;
break;
default:
Assert.Fail("No override given.");
return;
}
var isNotifiedActual = false;
Func <bool> testAction = () => actionSuccess;
void ListenerFunction(object sender, PropertyChangedEventArgs e)
{
isNotifiedActual = true;
}
PropertyChanged += ListenerFunction;
SetProperty <bool>(testAction, overrideNotification: overrideNotification);
Assert.AreEqual(isNotifiedExpected, isNotifiedActual);
PropertyChanged -= ListenerFunction;
}
public void SetProperty_FieldValueOverrideNotify_ListenersNotified(bool startValue, bool setValue, NotifyListeners overrideNotification)
{
bool isNotifiedExpected;
switch (overrideNotification)
{
case NotifyListeners.Always:
isNotifiedExpected = true;
break;
case NotifyListeners.Never:
isNotifiedExpected = false;
break;
default:
Assert.Fail("No override given.");
return;
}
var isNotifiedActual = false;
var testField = startValue;
void ListenerFunction(object sender, PropertyChangedEventArgs e)
{
isNotifiedActual = true;
}
PropertyChanged += ListenerFunction;
SetProperty <bool>(ref testField, setValue, overrideNotification: overrideNotification);
Assert.AreEqual(isNotifiedExpected, isNotifiedActual);
PropertyChanged -= ListenerFunction;
}
