编译器抱怨当Event有add&删除属性。无需编译就OK [英] Compiler complains when Event has add & remove properties. Compiles OK without

问题描述

我在这个SO回答之后对我的C＃4.0事件处理程序逻辑建模，并得到错误

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 -=

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);
        }
    }

但它编译时，

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

什么是首选方法？

推荐答案

而不是

EventHandler<EventLogAlert> handler = ThresholdExceededEvent;

使用

EventHandler<EventLogAlert> handler = thresholdExceededEventDelegate;

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