Chapter 2. Objects and Visual Basic

WHAT YOU WILL LEARN IN THIS CHAPTER

  • Object Oriented Terminology

  • Composition of an Object

  • Characteristics of Value Types versus Reference Types

  • Primitive Types

  • Commands: If Then, Else, Select Case

  • Common Value Types (Structures)

  • Common Reference Types (Classes)

  • XML literals

  • Parameter passing ByVal and ByRef

  • Variable scope

  • Working with Objects

  • Understanding Binding

  • Data type conversions

  • Creating Classes

  • Event Handling

  • Advanced Object Oriented Programming

  • Using Lambdas

Visual Basic supports the four major defining concepts required for a language to be fully object-oriented:

  • Abstraction — Abstraction is merely the ability of a language to create "black box" code, to take a concept and create an abstract representation of that concept within a program. A Customer object, for instance, is an abstract representation of a real-world customer. A DataTable object is an abstract representation of a set of data.

  • Encapsulation — Encapsulation is the concept of a separation between interface and implementation. The idea is that you can create an interface (public methods, properties, fields, and events in a class), and, as long as that interface remains consistent, the application can interact with your objects. This remains true even when you entirely rewrite the code within a given method — thus, the interface is independent of the implementation. The publicly exposed interface becomes what is known as a contract. It is this contract that you will look to limit changes to for ...

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