About delegate and event.

[Steven.Xu]

Hello, everyone.
As we know, some event definded like following:

public delegate MyEventDelegate (object pram);
public class ClassA
{
public event MyEventDelegate MyEvent;
}

My question is must I check the instance of "MyEvent" is exist before raise
the event. For example:
if (this.MyEvent != null) this.MyEvent(.. .);
I don't think same situation in VB.NET.

[Daniel O'Connell [C# MVP]]

Re: About delegate and event.


"Steven.Xu" <StevenXu@discu ssions.microsof t.com> wrote in message
news:6E6E4DC5-BD9E-4D9B-AF50-843DD86DE59E@mi crosoft.com...[color=blue]
> Hello, everyone.
> As we know, some event definded like following:
>
> public delegate MyEventDelegate (object pram);
> public class ClassA
> {
> public event MyEventDelegate MyEvent;
> }
>
> My question is must I check the instance of "MyEvent" is exist before
> raise
> the event. For example:[/color]
Because the C# compiler basically treats accessing the event from within the
defining class as accessing the underlying delegate field.
[color=blue]
> I don't think same situation in VB.NET.[/color]

I don't think VB uses the same syntax to raise an event as it does to call a
method, thus it is free to allow event invocation code to do a null check
where the equivilent C# code would be surprising.

C# could solve this by adding support for raise and generating a safe null
check for you in trivial events.