One of the authors, Harvey Deitel, remembers the great frustration that was felt in the 1960s by software development organizations, especially those working on large-scale projects. During his undergraduate years, he had the privilege of working summers at a leading computer vendor on the teams developing timesharing, virtual memory operating systems. This was a great experience for a college student. But, in the summer of 1967, reality set in when the company "decommitted" from producing as a commercial product the particular system on which hundreds of people had been working for many years. It was difficult to get this software right. Software is "complex stuff."
Improvements to software technology did emerge with the benefits of structured programming (and the related disciplines of structured systems analysis and design) being realized in the 1970s. Not until the technology of object-oriented programming became widely used in the 1990s, though, did software developers finally feel they had the necessary tools for making major strides in the software development process.
Actually, object technology dates back to the mid 1960s. The C++ programming language, developed at AT&T by Bjarne Stroustrup in the early 1980s, is based on two languagesC, which initially was developed at AT&T to implement the UNIX operating system in the early 1970s, and Simula 67, a simulation programming language developed in Europe and released in 1967. C++ absorbed the features of C and added Simula's capabilities for creating and manipulating objects. Neither C nor C++ was originally intended for wide use beyond the AT&T research laboratories. But grass roots support rapidly developed for each.
What are objects and why are they special? Actually, object technology is a packaging scheme that helps us create meaningful software units. These can be large and are highly focussed on particular applications areas. There are date objects, time objects, paycheck objects, invoice objects, audio objects, video objects, file objects, record objects and so on. In fact, almost any noun can be reasonably represented as an object.
We live in a world of objects. Just look around you. There are cars, planes, people, animals, buildings, traffic lights, elevators and the like. Before object-oriented languages appeared, programming languages (such as FORTRAN, COBOL, Pascal, Basic and C) were focussed on actions (verbs) rather than on things or objects (nouns). Programmers living in a world of objects programmed primarily using verbs. This made it awkward to write programs. Now, with the availability of popular object-oriented languages such as C++ and Java, programmers continue to live in an object-oriented world and can program in an object-oriented manner. This is a more natural process than procedural programming and has resulted in significant productivity enhancements.
A key problem with procedural programming is that the program units do not easily mirror real-world entities effectively, so these units are not particularly reusable. It is not unusual for programmers to "start fresh" on each new project and have to write similar software "from scratch." This wastes time and money, as people repeatedly "reinvent the wheel." With object technology, the software entities created (called classes), if properly designed, tend to be much more reusable on future projects. Using libraries of reusable componentry, such as MFC (Microsoft Foundation Classes), Microsoft's .NET Framework Class Library and those produced by Rogue Wave and many other software development organizations, can greatly reduce the amount of effort required to implement certain kinds of systems (compared to the effort that would be required to reinvent these capabilities on new projects).
Software Engineering Observation 1.3
Extensive class libraries of reusable software components are available over the Internet and the World Wide Web. Many of these libraries are available at no charge.
Some organizations report that the key benefit object-oriented programming gives them is not software reuse. Rather, they indicate that it tends to produce software that is more understandable, better organized and easier to maintain, modify and debug. This can be significant, because it has been estimated that as much as 80 percent of software costs are associated not with the original efforts to develop the software, but with the continued evolution and maintenance of that software throughout its lifetime.
Whatever the perceived benefits of object orientation are, it is clear that object-oriented programming will be the key programming methodology for the next several decades.