Overview of Object-Oriented Programming TO SET THE STAGE for your study of object-oriented programming and Visual Basic.NET, this chapter will briefly look at the history of object-oriented programming and the characteristics of an object-oriented programming language. You will look at why object-oriented programming has become so important in the development of industrial-strength distributed software systems. You will also examine how Visual Basic has evolved into one of the leading business application programming languages.After reading this chapter you will be familiar with the following:• The history of object-oriented programming • Why object-oriented programming has become so important in the development of industrial-strength applications • The characteristics that make a programming language object-oriented• The history and evolution of Visual BasicThe History of OOP Object-Oriented Programming (OOP) is an approach to software development in which the structure of the software is based on objects interacting with each other to accomplish a task. This interaction takes the form of messages passing back and forth between the objects. In response to a message, an object can performance action, or method. If you look at how you accomplish tasks in the world around you, you can see that you interact in an object-oriented world. If you want to go to the store, for example, you interact with a car object. A car object consists of other objects that interact with each other to accomplish the task of getting you to the store. You put the key in the ignition object and turn it. This in turn sends a message (through an electrical signal) to the starter object, which interacts with the engine object to start the car. As a driver, you are isolated from the logic of how the objects of the system work together to start the car. You just initiate the sequence of events by executing the start method of the ignition object with the key. You then wait for a response (message) of success or failure.Object-oriented programs consist of objects that interact with each other to accomplish a task. Like the real world, users of software programs are isolated from the logic needed to accomplish a task. For example, when you print a page in your word processor, you initiate the action by clicking a print button. You are isolated from the internal processing that has to occur—you just wait fora response telling you if it printed. Internally, the button object interacts with a printer object, which interacts with the printer to accomplish the task of printing the page.OOP concepts started surfacing in the mid-1960s with a programming language called Simula and further evolved in the 70s with advent of Smalltalk.Although software developers did not overwhelmingly embrace these early advances in OOP languages, object-oriented methodologies continued to evolve.In the mid-80s there was a resurgence of interest in object-oriented methodologies. Specifically, OOP languages such as C++ and Eifle became popular with mainstream computer programmers. OOP continued to grow in popularity in the90s, most notably with the advent of Java and the huge following it attracted. And in 2002, with the latest version of Visual Studio, Microsoft introduced a new OOP language, C# (pronounced C-sharp) and revamped Visual Basic so that it is truly an OOP language.
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