Reactive UI中各种WhenAny方法之间的区别是什么

Question

Reactive UI中有几种扩展方法,用于获取属性更改的可观察对象.

我想我明白WhenAny和WhenAnyValue. WhenAny用于一系列属性更改通知,其中您希望哪个对象和属性的元数据发生了更改,而WhenAnyValue当您真正想要更改值的流时.

首先,这是一个准确的评估吗？

怎么样WhenAnyDynamic,WhenAnyObservable和ObservableForProperty？我无法弄清楚它们的用途,或者它们与前两个有何不同.它们都是供公众使用的吗？他们的目的是什么？

Answer 1

我想我理解WhenAny和WhenAnyValue.

让我通过代码演示:

// These two statements are 100% identical, but the latter looks nicer.
this.WhenAny(x => x.Foo.Bar, x => x.Value)

this.WhenAnyValue(x => x.Foo.Bar);

那么WhenAnyDynamic,WhenAnyObservable和ObservableForProperty怎么样？

WhenAnyDynamic 就像WhenAny,但是当你想要观察的东西不是常数时 - 你可能不需要它,但是RxUI内部会这样做.

WhenAnyObservable让你获得一个Observable,但不必担心背后的物体变化.例如

this.SomeChildViewModel.MyCoolCommand
    .Subscribe(x => Console.WriteLine("Clicked!"));

// Later...
this.SomeChildViewModel = new SomeChildViewModel();

// (Hey, why doesn't my Clicked! handler show up anymore! I'm still subscribed
// to the old object but it's super not obvious that's what happened)

与

this.WhenAnyObservable(x => x.MyCoolCommand).
    .Subscribe(x => Console.WriteLine("Clicked!"));

// Later...
this.SomeChildViewModel = new SomeChildViewModel();

// Cool, everything still works.

WhenAnyObservable在View to Subscribe to Commands中非常有用.

ObservableForProperty就像WhenAny但最初订阅时不会触发.您可能应该忽略它,它实际上只是出于兼容性原因而出现的WhenAny的构建块.