如何在C#中可见的F#中定义事件 [英] How do define an event in F# visible from C#

问题描述

查看文档的各个方面，在F#中定义事件的方法是执行类似

Looking at various bits of documentation, the way of defining an event in F# is to do something like

type xyz () =
    let e = new Event<T>
    member x.something_happened : IEvent<T> = x.Publish

不幸的是，IEvent的类型实际上是Miscrosoft.FSharp.Control.IEvent< __，因此很难在C#中使用.一些文章建议将CLIEvent属性添加到上面的something_happended成员，但是就其在C#中的可用性(不包括F#库)而言，似乎没有什么区别.

Unfortunately, the type of IEvent is really Miscrosoft.FSharp.Control.IEvent<_>, and it is hence difficult to use from within C#. Some articles suggest adding the CLIEvent attribute to member something_happended above but it seems to make no difference as far as its usability from C# without including the F# library goes.

如何正确定义F#中的事件，以便随后可以使用C#代码向其添加委托?非常感谢.

How do I correctly define an event in F# so I can then add a delegate to it in C# code? Many thanks.

推荐答案

F#中有两种事件类型， Event<'T> 和 Event<'Delegate, 'Args> .存在[<CLIEvent>]时，仅第二个事件被编译为.NET事件.这是一个工作示例:

There are two event types in F#, Event<'T> and Event<'Delegate, 'Args>. Only the second one is compiled to a .NET event when [<CLIEvent>] is present. Here's a working example:

type T() =
    let e = Event<EventHandler<_>,_>()

    [<CLIEvent>]
    member x.MyEvent = e.Publish

    member x.RaiseMyEvent() = e.Trigger(x, EventArgs.Empty)

在某些情况下，如果[<CLIEvent>]与非标准事件类型一起使用，则编译器会生成警告.我不确定为什么它不会对您的代码发出警告(也许是错误?).

In some cases the compiler generates a warning if [<CLIEvent>] is used with a non-standard event type. I'm not sure why it doesn't raise a warning for your code (perhaps a bug?).

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