Tutorial by Examples

Abstraction levels help determine when to split things up. Abstraction is achieved by implementing functionality with increasingly detailed code. The entry point of a macro should be a small procedure with a high abstraction level that makes it easy to grasp at a glance what's going on: Public Sub...

Encapsulation hides implementation details from client code. The Handling QueryClose example demonstrates encapsulation: the form has a checkbox control, but its client code doesn't work with it directly - the checkbox is an implementation detail, what the client code needs to know is whether the s...

Polymorphism is the ability to present the same interface for different underlying implementations. The ability to implement interfaces allows completely decoupling the application logic from the UI, or from the database, or from this or that worksheet. Say you have an ISomeView interface that the...