Ooad

The Evolution of Object Orientation

The design of program that reflects object and their behaviour in real world scenario is object oriented programming

It is an approach to defining a solution to a problem that uses the system's natural structure. Rather than considering procedures and data as being separate, object orientation unifies them into a single entity called an object.

In 1960's developers realize that programming system should be broken in small and manageable pieces. Simula was created to help simulation. Although it never became widely used language, but used to design its successors. Its designers were Ole-Johan Dahl and Kristen Nygaard, who developed Simula at the Norwegian Computing Centre in Oslo. What they had originally invented in 1962 was a simple simulation procedure package along with a preprocessor for ALGOL 60.It was originally used for discrete event simulation and then expanded as general purpose programming language. Simula introduced most important object oriented concepts like object, class, inheritance and dynamic binding. It has also introduced instantiation of subroutines with storage capacity for inputs and local variables that can interact as object with other subroutines.

First truly O-O language was Smalltalk, designed by Alan Kay and implemented by Dan Ingalls at the Ð''Learning Research Group' at Xerox's Palo Alto Research Center in the early 1970s. In Smalltalk, everything is really an object. It is impossible to write a program in Smalltalk that is not O-O. This is not the case for other languages that support objects, such as C++ and Java, you can actually change the parameters and code of a program while the program is running. Smalltalk used to develop application such as browsers, windows, and pop-up menus. Smalltalk supported inheritance and the message passing between objects.

Eiffel was a language designed by Bertrand Meyer (1988) to implement Ð''design by contract'. Meyer's work in this area was an attempt to formalize object-oriented programming, and was moderately successful.

Although O-O development gained certain amount of popularity in the marketplace, it took C++ to bring O-O development. C++ has its roots in project to simulate software running on a distributed system. Bjarne Stroustrup integrated the idea of combining some of the features of Simula with the syntax of C. Brian Kernighan and Dennis Ritchie, wrote the definitive book on C. When the initial simulator written in Simula failed, Stroustrup decided to rewrite it in a C predecessor called BCPL. C++ was originally implemented in 1982 under the name C with Classes. As the name suggests, the most important