public static string GetPropertyName <TSource, TProp>(this TSource source,
Expression <Func <TSource, TProp> > propertyExpression)
{
var memberExpression = CompiledExpressionHelper <TSource, TProp> .GetMemberExpression(propertyExpression);
return(memberExpression.Member.Name);
}
public static IObservable <TProperty> ObserveProperty <TSource, TProperty>(this TSource source, Expression <Func <TSource, TProperty> > propertyExpression, bool observeInitialValue = false)
where TSource : INotifyPropertyChanged
{
return(Observable.Create <TProperty>(observer =>
{
var propertyName = GetPropertyName(propertyExpression);
var selector = CompiledExpressionHelper <TSource, TProperty> .GetFunc(propertyExpression);
var observable = Observable.FromEventPattern <PropertyChangedEventHandler, PropertyChangedEventArgs>(h => source.PropertyChanged += h,
h => source.PropertyChanged -= h)
.Where(evt => evt.EventArgs.PropertyName == propertyName)
.Select(_ => selector(source));
return (observeInitialValue ? observable.StartWith(selector(source)) : observable).Subscribe(observer);
}));
}
public static IObservable <TProp> ObserveProperty <TSource, TProp>(this TSource source,
Expression <Func <TSource, TProp> > propertyExpression,
bool observeInitialValue)
where TSource : INotifyPropertyChanged
{
return(Observable.Create <TProp>(o =>
{
var propertyName = GetPropertyName(source, propertyExpression);
var selector = CompiledExpressionHelper <TSource, TProp> .GetFunc(propertyExpression);
var observable
= from evt in Observable.FromEvent <PropertyChangedEventHandler, PropertyChangedEventArgs>(
h => (s, e) => h(e),
h => source.PropertyChanged += h,
h => source.PropertyChanged -= h)
where evt.PropertyName == propertyName
select selector(source);
observable = observeInitialValue ? observable.StartWith(selector(source)) : observable;
return observable.Subscribe(o);
}));
}
private static string GetPropertyName <TSource, TProperty>(Expression <Func <TSource, TProperty> > propertyExpression) where TSource : INotifyPropertyChanged
{
return(CompiledExpressionHelper <TSource, TProperty> .GetMemberExpression(propertyExpression).Member.Name);
}
