Calling a method from a delegate.

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1.00/5 (1 vote)

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I need to call a method from a delegate that can also access some ui controls. Problem occurred during data acquisition, delegate is called whenever memory buffer is filled, then I need to updated some values on display and record the data.

What I have tried:

public delegate void CallbackDelegate();

        static CallbackDelegate myDelegate;
        static int count = 0;
        static private void CallBack_DBEvent()
        {
            count++;
            Display();
            // getting error
            //An object reference is required for the non-static field, method, or property 'WindowsFormsApplication1.Form1.Display()'
        }

        public void Display()
        {
            textBox1.Text = count.ToString();
        }

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            myDelegate = new CallbackDelegate(CallBack_DBEvent);
            CallBack_DBEvent();
        }

Posted 30-Nov-17 0:13am

Rao Tahir

Updated 30-Nov-17 20:12pm

RaviRanjanKr

v4

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Comments

Richard MacCutchan 30-Nov-17 6:40am

And? What happens when you do so?

Nathan Minier 30-Nov-17 7:29am

Follow up to Richard's question: Is this running on a different thread?

Rao Tahir 30-Nov-17 8:48am

I have updated the code, that is the summary of what i am doing in actual program. CallBack_DBEvent() is actually called externally, means "this function is called when memory is full" and then i need to do some operation , like updating number of samples received.

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OriginalGriff · Accepted Answer · 2017-11-30T01:51:00

Declare your delegate and some "target" methods with matching signatures

delegate void myDelegate(string name);
static void myFunction1(string name)
    {
    Console.WriteLine("1: " + name);
    }
static void myFunction2(string name)
    {
    Console.WriteLine("2: " + name);
    }

Then call them:

myDelegate del = new myDelegate(myFunction1);
del("Joe Smith");
del = new myDelegate(myFunction2);
del("Mike Brown");

You can also call it with an anonymous method:

del = delegate(string name) { Console.WriteLine("Anon: " + name); };
del("Jane Doe");

Or a Lambda:

del = name => { Console.WriteLine("Lambda: " + name); };
del("Mary Jane");