当事件添加&删除属性。编译OK没有 [英] Compiler complains when Event has add & remove properties. Compiles OK without

问题描述

在此SO答案之后，我正在建模我的C＃4.0事件处理程序逻辑，并获得错误

I'm modeling my C# 4.0 event handler logic after this SO answer and get the error

ThresholdExceededEvent只能出现在+ =或 - =

ThresholdExceededEvent can only appear on the left hand side of += or -=

$ b的左侧$ b

代码

    private EventHandler<EventLogAlert> thresholdExceededEventDelegate;
    public event EventHandler<EventLogAlert> ThresholdExceededEvent
    {
        add { thresholdExceededEventDelegate += value; Console.WriteLine("add operation"); }
        remove { thresholdExceededEventDelegate -= value; Console.WriteLine("remove operation"); }
    }

    protected virtual void OnThresholdExceededEvent(EventLogAlert e)
    {
        EventHandler<EventLogAlert> handler = ThresholdExceededEvent;
        if (handler != null)
        {
            handler(this, e);
        }
    }

但是当我这样做时会编译....

but it compiles when I do this....

   public event EventHandler<EventLogAlert> ThresholdExceededEvent;
    protected virtual void OnThresholdExceededEvent(EventLogAlert e)
    {
        EventHandler<EventLogAlert> handler = ThresholdExceededEvent;
        if (handler != null)
        {
            handler(this, e);
        }
    }

首选方法是什么？

推荐答案

而不是

EventHandler<EventLogAlert> handler = ThresholdExceededEvent;

使用

EventHandler<EventLogAlert> handler = thresholdExceededEventDelegate;

这篇关于当事件添加&删除属性。编译OK没有的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！