public static PropertyObserver <TType> Create <TType>([NotNull] Expression <Func <TType> > propertyExpression)
{
var instance = new PropertyObserver <TType>(propertyExpression);
instance.Subscribe();
return(instance);
}
/// <summary>
/// Initializes a new instance of the <see cref="PropertyObserver{TOwner,T}" /> class.
/// </summary>
/// <param name="propertyExpression">The property expression.</param>
private PropertyObserver([NotNull] Expression <Func <T> > propertyExpression)
{
if (propertyExpression == null)
{
throw new ArgumentNullException(nameof(propertyExpression));
}
this.Observer = PropertyObserver.Observes(propertyExpression, () => this.Update.Raise(), false);
}
/// <summary>
/// Initializes a new instance of the <see cref="CanExecuteObserver" /> class.
/// </summary>
/// <param name="canExecuteExpression">The can execute expression.</param>
/// <exception cref="ArgumentNullException">canExecuteExpression</exception>
public CanExecuteObserver([NotNull] Expression <Func <bool> > canExecuteExpression)
{
if (canExecuteExpression == null)
{
throw new ArgumentNullException(nameof(canExecuteExpression));
}
this.Observer = PropertyObserver.Observes(canExecuteExpression, () =>
{
this.Update.Raise();
}, false);
this.Owner = this.Observer.Owner ?? throw new NullReferenceException(nameof(this.Owner));
this.CanExecute = canExecuteExpression.Compile();
}
/// <summary>
/// Adds the expression.
/// </summary>
/// <param name="propertyExpression">The property expression.</param>
/// <exception cref="System.ArgumentException">propertyExpression</exception>
public void AddExpression(Expression <Func <T> > propertyExpression)
{
if (this.observedPropertiesExpressions.TryGetValue(propertyExpression.ToString(), out _))
{
throw new ArgumentException(
$"{propertyExpression} is already being observed.",
nameof(propertyExpression));
}
var observer = PropertyObserver.Observes(propertyExpression, () => this.Update.Raise());
this.observedPropertiesExpressions.Add(propertyExpression.ToString(), observer);
observer.Subscribe();
}
/// <summary>
/// Initializes a new instance of the <see cref="PropertyObserver{TOwner, T}" /> class.
/// </summary>
/// <param name="owner">The owner.</param>
/// <param name="propertyExpression">The property expression.</param>
public PropertyObserver(TOwner owner, Expression <Func <TOwner, T> > propertyExpression)
{
if (owner == null)
{
throw new ArgumentNullException(nameof(owner));
}
if (propertyExpression == null)
{
throw new ArgumentNullException(nameof(propertyExpression));
}
this.Owner = owner;
this.Observer = PropertyObserver.Observes(owner, propertyExpression, () => this.Update.Raise(), false);
}
/// <summary>
/// Initializes a new instance of the <see cref="CanExecuteObserver{TOwner}" /> class.
/// </summary>
/// <param name="owner">The owner.</param>
/// <param name="canExecuteExpression">The can execute expression.</param>
/// <exception cref="ArgumentNullException"></exception>
public CanExecuteObserver([NotNull] TOwner owner, [NotNull] Expression <Func <TOwner, bool> > canExecuteExpression)
{
if (owner == null)
{
throw new ArgumentNullException(nameof(owner));
}
if (canExecuteExpression == null)
{
throw new ArgumentNullException(nameof(canExecuteExpression));
}
this.Owner = owner;
this.Observer = PropertyObserver.Observes(owner, canExecuteExpression, () => this.Update.Raise(), false);
this.CanExecute = () => canExecuteExpression.Compile()(owner);
}
/// <summary>
/// Adds the expression.
/// </summary>
/// <typeparam name="TOwner">The type of the owner.</typeparam>
/// <param name="owner">The owner.</param>
/// <param name="propertyExpression">The property expression.</param>
/// <exception cref="ArgumentException">propertyExpression</exception>
public void AddExpression <TOwner>(TOwner owner, Expression <Func <TOwner, T> > propertyExpression)
where TOwner : INotifyPropertyChanged
{
if (this.observedPropertiesExpressions.TryGetValue(
owner.GetHashCode() + propertyExpression.ToString(),
out _))
{
throw new ArgumentException(
$"{propertyExpression} is already being observed.",
nameof(propertyExpression));
}
var observer = PropertyObserver.Observes(owner, propertyExpression, () => this.Update.Raise());
this.observedPropertiesExpressions.Add(owner.GetHashCode() + propertyExpression.ToString(), observer);
observer.Subscribe();
}
