我是MVVM设计模式的新手，我有以下viewmodels：
ClassAViewModel
public class ClassAViewModel : INotifyPropertyChanged
{
private int _nbre = 0;
public int Nbre
{
get
{
return _nbre;
}
set
{
_nbre = value;
PropertyChanged(this, new PropertyChangedEventArgs("Nbre"));
}
}
#region Events
public event PropertyChangedEventHandler PropertyChanged;
#endregion
}
和ClassBViewModel
PUBLIC class ClassBViewModel: INotifyPropertyChanged
{
private Boolean _IsBiggerthanFive = false;
public bool IsBiggerthanFive
{
get
{
return _IsBiggerthanFive;
}
set
{
_IsBiggerthanFive = value;
PropertyChanged(this, new PropertyChangedEventArgs("IsBiggerthanFive"));
}
}
#region Events
public event PropertyChangedEventHandler PropertyChanged;
#endregion
}
我需要知道两个视图模型之间是否存在通知机制，即在我的情况下，如果_nbre > 5在第一个视图模型中，将通知第二个视图模型，并且的值_IsBiggerthanFive将更改。所以：
我同意其他评论者的意见，认为调解员/发布子/事件聚合器/信使是一个不错的选择。如果您不将MVVM框架与内置解决方案一起使用，那么我建议您采用利用Reactive扩展的简单方法：
public class EventPublisher : IEventPublisher
{
private readonly ConcurrentDictionary<Type, object> subjects
= new ConcurrentDictionary<Type, object>();
public IObservable<TEvent> GetEvent<TEvent>()
{
var subject =
(ISubject<TEvent>) subjects.GetOrAdd(typeof (TEvent),
t => new Subject<TEvent>());
return subject.AsObservable();
}
public void Publish<TEvent>(TEvent sampleEvent)
{
object subject;
if (subjects.TryGetValue(typeof(TEvent), out subject))
{
((ISubject<TEvent>)subject)
.OnNext(sampleEvent);
}
}
}
这就是您的整个事件汇总器。将其实例传递到每个视图模型中，并将其存储为参考。然后创建一个类来存储事件详细信息，比如说“ ValueChangedEvent”：
public class ValueChangedEvent
{
public int Value
{
get { return _value; }
}
private readonly int _value;
public ValueChangedEvent(int value)
{
_value = value;
}
}
从第一个视图模型发布如下：
set
{
_nbre = value;
PropertyChanged(this, new PropertyChangedEventArgs("Nbre"));
_eventPublisher.Publish(new ValueChangedEvent(value));
}
使用GetEvent以下内容订阅其他课程：
public class ClassBViewModel: INotifyPropertyChanged, IDisposable
{
private readonly IDisposable _subscriber;
public ClassBViewModel(IEventPublisher eventPublisher)
{
_subscriber = eventPublisher.Subscribe<ValueChangedEvent>(next =>
{
IsBiggerthanFive = next.Value > 5;
});
}
public void Dispose()
{
_subscriber.Dispose();
}
}
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