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Object Technology

Object technology has become the subject of intense marketing, as competing companies apply the label to whatever they were doing anyway. Consequently, it is necessary to dig fairly deep to understand exactly what is going on. The essential idea of a software object is a package containing both some data and the methods that operate on that data. This packaging has several good results.

  • Encapsulation—objects hide the details of their implementation.

    Objects are a step beyond subroutine libraries, or Application Programming Interfaces (APIs). The programmer who develops software using APIs must understand how data is represented and stored. With object technology, the object is responsible for the data, not the programmer making use of the object to accomplish some higher goal. Encapsulation not only makes it unnecessary for the programmer to learn about the internal details of the object, it makes it impossible. This sounds heavy-handed, but it greatly reduces both immediate problems and latent bugs.

  • Polymorphism—there can be multiple implementations of an object.

    Once a particular concept, such as a bank account, has been represented as an object, variations of the concept, such as a checking account or a savings account, can be represented as different implementations of an object, each with the same interface. When this is done, applications that operate on the account, such as the application that computes interest due each month, do not even need to know that there are different kinds of accounts.

  • Language binding—objects can be implemented in different languages.

    The internal communications between one part of a program and another part are usually orchestrated by the language and its compiler. However, because the object technology carefully defines the ways in which one object can call another, there is no need for all the objects in a system to be coded in the same language. Instead, each language system provides a translation to the standard communications machinery defined by the object system.


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