Code:
namespace interfaceevents
{
using System;
public interface square
{
event EventHandler Draw;
}
public interface rectangle
{
event EventHandler Draw;
}
public class Shape : square, rectangle
{
event EventHandler DrawEvent1;
event EventHandler DrawEvent2;
object objectLock = new Object();
event EventHandler square.Draw
{
add
{
lock (objectLock)
{
DrawEvent1 += value;
}
}
remove
{
lock (objectLock)
{
DrawEvent1 -= value;
}
}
}
event EventHandler rectangle.Draw
{
add
{
DrawEvent2 += value;
}
remove
{
DrawEvent2 -= value;
}
}
public void Draw()
{
EventHandler handler = DrawEvent1;
if (handler != null)
{
handler(this, new EventArgs());
}
Console.WriteLine("Drawing a shape.");
handler = DrawEvent2;
if (handler != null)
{
handler(this, new EventArgs());
}
}
}
public class classA
{
// References the shape object as an square
public classA(Shape shape)
{
square d = (square)shape;
d.Draw += new EventHandler(d_Draw);
}
void d_Draw(object sender, EventArgs e)
{
Console.WriteLine("ClassA receives the square event.");
}
}
public class classB
{
public classB(Shape shape)
{
rectangle d = (rectangle)shape;
d.Draw += new EventHandler(d_Draw);
}
void d_Draw(object sender, EventArgs e)
{
Console.WriteLine("ClassB receives the rectangle event.");
}
}
public class Program
{
static void Main(string[] args)
{
Shape shape = new Shape();
classA sub = new classA(shape);
classB sub2 = new classB(shape);
shape.Draw();
System.Console.WriteLine("Press any key to exit.");
System.Console.ReadKey();
}
}
}
Output:
ClassA receives the Square event.
Drawing a shape.
ClassB receives the Rectangle event.
Press any key to exit.
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