Programate algo - Programming Blog/Blog de Programación

Spanish version / Versión en Español Say we: Have a class we want to divide into subclasses The future base class has events The refactoring leads us to the need of raising an event declared in the base class, from a derived class. When we try to do point 3, we will get a compile error saying that a derived class cannot raise events from a base class. To get around this, we add a protected method in the base class which encapsulates the RaiseEvent call, and call that method from the derived class using MyBase. This way: In the base class (parameters as needed): Protected Overridable Sub OnMessageGenerated(ByVal NewSender As Object, ByVal NewMessage As String) RaiseEvent MessageGenerated(NewSender, New MessageEventArgs(NewMessage)) End Sub And in the derived class: 'Do stuff 'Raise base class event MyBase.OnMessageGenerated( Me, "Message" ) 'Do more stuff... References: Mark Gilbert post

Spanish version / Versión en Español In the previous post, we saw how to trigger an event from a C++ native class which has a C++/CLI wrapper as an interface to .NET. We dealt with the general case in which we wish to pass non trivial information (a class or a struct) along with the event. Today we'll see the more simple case in which we just need to pass a float or some other basic CLR type. As expected, things are quite simpler. In the native class, just for convenience, define a pointer to function type. Both returnType and parameters should be basic CLR types. typedef <returnType> ( __stdcall * PFOnEventCallback )( <parameters> ); In the same class, declare a field of that type: PFOnEventCallback m_fireEvent; Still in the native class, go to where you wish to trigger the event: if (m_fireEvent) m_fireEvent( <parameters> ); (It's good practice to initialize m_fireEvent to 0 or NULL, your cho...

Spanish version / Versión en Español Imagine we want to trigger an event from a native class which has a C++/CLI wrapper as an interface to managed code (C#, VB.NET). And let's deal with the general case in which we desire to pass extra information along with the event, and said information is not inside a CLR basic type, that is one which both native and managed C++ understand (int, float, char, and so on). In the native class, declare, just for convenience, a pointer to function type: typedef <nativeReturnType> ( __stdcall * PFOnEventCallback )( <nativeParameters> ); Still in the native class, declare a field of the type declared in 1): PFOnEventCallback m_fireEvent; In the place in the native class where we want to trigger the event: if( m_fireEvent ) m_fireEvent( <nativeParameters> ); (This suggests you to initialize m_fireEvent to 0, or NULL if you prefer) Now we need a setter for m_...