C#

DaveyM69 wrote:

then my article[^] for a more complete tutorial

glennPattonWork wrote:

all seems to be forward and not backward passing

// ThreeIntsEventArgs.cs
/* Arguments and delegate for FormChild.ThreeIntsEvent */

using System;

public delegate void ThreeIntsEventHandler(object sender, ThreeIntsEventArgs e);

public class ThreeIntsEventArgs : EventArgs
{
    private int x;
    private int y;
    private int z;

    public ThreeIntsEventArgs(int x, int y, int z)
    {
        this.x = x;
        this.y = y;
        this.z = z;
    }

    public int X
    {
        get { return x; }
    }
    public int Y
    {
        get { return y; }
    }
    public int Z
    {
        get { return z; }
    }
}

// FormChild.cs
/* Click OK to raise event sending the three values */

using System.Drawing;
using System.Windows.Forms;

public partial class FormChild : Form
{
    public event ThreeIntsEventHandler ThreeInts;

    private NumericUpDown numericUpDownX;
    private NumericUpDown numericUpDownY;
    private NumericUpDown numericUpDownZ;
    private Button buttonOK;

    public FormChild()
    {
        InitializeComponent();
        // numericUpDownX
        numericUpDownX = new NumericUpDown();
        numericUpDownX.Location = new Point(12, 12);
        // numericUpDownY
        numericUpDownY = new NumericUpDown();
        numericUpDownY.Location = new Point(12, 36);
        // numericUpDownZ
        numericUpDownZ = new NumericUpDown();
        numericUpDownZ.Location = new Point(12, 60);
        // buttonOK
        buttonOK = new Button();
        buttonOK.Text = "OK";
        buttonOK.Location = new Point(12, 84);
        buttonOK.Click += new System.EventHandler(buttonOK_Click);
        // Add controls
        Controls.AddRange(new Control[] { numericUpDownX, numericUpDownY, numericUpDownZ, buttonOK });
        AcceptButton = buttonOK;
    }

    private void buttonOK_Click(object sender, System.EventArgs e)
    {
        OnThreeInts(new ThreeIntsEventArgs((int)numericUpDownX.Value, (int)numericUpDownY.Value, (int)numericUpDownZ.Value));
    }
    protected virtual void OnThreeInts(ThreeIntsEventArgs e)
    {
        ThreeIntsEventHandler eh = ThreeInts;
        if (eh != null)
            eh(this, e);
    }
}

// FormParent.cs
/* Click the Form tho open a new child and subscribe to the event */

using System.Windows.Forms;

public partial class FormParent : Form
{
    public FormParent()
    {
        InitializeComponent();
        Click += new System.EventHandler(FormParent_Click);
    }

    private void FormParent_Click(object sender, System.EventArgs e)
    {
        FormChild formChild = new FormChild();
        // Subscribe
        formChild.ThreeInts += new ThreeIntsEventHandler(formChild_ThreeInts);
        formChild.Show();
    }
    // Handle event
    private void formChild_ThreeInts(object sender, ThreeIntsEventArgs e)
    {
        MessageBox.Show(string.Format("X: {0}, Y: {1}, Z:{2}", e.X, e.Y, e.Z));
    }
}

((A)C).M();

a.M();
b.M();
c.M();

A
A
A

((A)a).M();
((B)b).M();
((C)c).M();

A
B
C