Microsoft Visual C++ .NET(c) Step by Step

Define a delegate.

Use the __delegate keyword with a function prototype. For example:

__delegate void DelegateOne(double d);

Create a delegate bound to a static class member.

Use new to create a Delegate object, passing 0 for the first parameter and the address of the static function as the second parameter. For example:

DelegateOne* pDel = new DelegateOne(0, &MyClass::MyFunc);

Create a delegate bound to a non-static class member.

Use new to create a Delegate object, passing a pointer to the instance for the first parameter and the address of the member function as the second parameter. For example:

DelegateOne* pDel = new DelegateOne( pMyObject, &MyClass::MyOtherFunc);

Execute the function bound to a delegate.

Use the delegate’s Invoke function, passing any parameters required. For example:

pDel->Invoke(22.7);

Create an event.

First define a delegate to define the handler routine for this event, as follows:

__delegate void ClickHandler(int, int);

Then, in the event source class, use the __event keyword to define an event object, like this:

__event ClickHandler* OnClick;

Raise an event.

Use the event object as if it were a function, passing any parameters. For example:

OnClick(xVal, yVal);

Subscribe to an event.

Use the += operator. For example:

mySrc->OnClick += new ClickHandler(this, &myHandler);

Unsubscribe from an event.

Use the -= operator. For example:

mySrc->OnClick -= new ClickHandler(this, &myHandler);