i am trying to make use of events in C#. I am really new to events. Following is my code.
public void GetVoltage(Object objName, Object objCcaVar)
{
DynamicSystemVariable mysys = new DynamicSystemVariable("VTS::M9_Ch3", "AvgVoltage");
mysys.ValueChanged += (sender, e) => mysys_ValueChanged(sender, e, ""); ;
}
void mysys_ValueChanged(object sender, EventArgs e,String name)
{
DynamicSystemVariable mysys = (DynamicSystemVariable)sender;
Output.WriteLine(mysys.GetValue().ToString());
Output.WriteLine("System Variable Changed");
if (_unwireEvent)
mysys.ValueChanged -= mysys_ValueChanged;
}
It gives me following error on the line where i am unwiring it. No overload for 'mysys_ValueChanged' matches delegate 'System.EventHandler'
I will appreciate if somebody can help me out.
Thanks Tom
Instead of sending name
as a seperate parameter, create a new class deriving from EventArgs
and add name
parameter to this class as a property. Something like;
public class MyEventArgs : EventArgs
{
public string Name {get; private set;}
public MyEventArgs(EventArg e, string name)
{
this.Name = name;
}
}
mysys.ValueChanged += mysys_ValueChanged(sender, new MyEventArgs("some name"));
Also do not forget to change the signiture of mysys_ValueChanged
.
Note that this is just a workaround, and proper way is defining a new delegate which uses MyEventArgs
and using a seperate handling method instead of an inline method.
The problem is that you haven't register mysys_ValueChanged
. You registered an anonymous method.
You have to change your code to:
public void GetVoltage(Object objName, Object objCcaVar)
{
DynamicSystemVariable mysys = new DynamicSystemVariable("VTS::M9_Ch3", "AvgVoltage");
mysys.ValueChanged += this.OnEvent;
}
private void OnEvent(object sender, EventArgs e)
{
mysys_ValueChanged(sender, e, "");
}
void mysys_ValueChanged(object sender, EventArgs e,String name)
{
DynamicSystemVariable mysys = (DynamicSystemVariable)sender;
Output.WriteLine(mysys.GetValue().ToString());
Output.WriteLine("System Variable Changed");
if (_unwireEvent)
mysys.ValueChanged -= OnEvent; // Unregister what you've registered.
}
EDIT
Having new input it could be solved that way:
public void GetVoltage(Object objName, Object objCcaVar)
{
DynamicSystemVariable mysys = new DynamicSystemVariable("VTS::M9_Ch3", "AvgVoltage");
EventHandler<EventArgs> handler = null;
handler = (s, e) => mysys_ValueChanged(s, e, "", handler);
mysys.ValueChanged += handler;
}
void mysys_ValueChanged(object sender, EventArgs e, String name, EventHandler<EventArgs> handler)
{
DynamicSystemVariable mysys = (DynamicSystemVariable)sender;
Output.WriteLine(mysys.GetValue().ToString());
Output.WriteLine("System Variable Changed");
if (_unwireEvent)
mysys.ValueChanged -= handler; // Unregister what you've registered.
}
I haven't tried it but I think this could work - but in my opinion it's hacked.
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