OBJECT-ORIENTED LANGUAGES AND APPLICATIONS

Computer historians believe that SIMULA (SIMUlation LAnguage) was the first computer language to work with objects, classes, inheritance, and methods. SIMULA was developed in 1962 by two Norwegian computer scientists for the purpose of programming simulations and models. SIMULA laid the foundation for the object-oriented paradigm, which was later incorporated into other programming languages, such as Eiffel, Smalltalk, C++, and Java.

The second major development in object-oriented languages came in 1972 when Alan Kaye began work on the Dynabook project at the Xerox Palo Alto Research Center (PARC). Dynabook was a prototype for a notebook-sized personal computer, intended to handle all the information needs of adults and children. Kaye developed a programming language called Smalltalk for the Dynabook that could be easily used to create programs based on real-world objects. Dynabook never became a commercial product, but Smalltalk survived and is still in use today. Smalltalk is regarded as a classic object-oriented language, which encourages programmers to take a “pure” OO approach to the programming process.

As the object-oriented paradigm gained popularity, several existing programming languages were modified to allow programmers to work with objects, classes, inheritance, and polymorphism. The concept for the Ada programming language originated in 1978 at the U. S. Department of Defense. The first versions of Ada were procedural, but in 1995, the language was modified to incorporate object-oriented features. A similar transformation took place with the C language in 1983, except that the object-oriented version earned a new name — C++. Hybrid languages, such as Ada95, C++, Visual Basic, and C#, give programmers the option of using procedural and object-oriented techniques.

Java is one of the newest additions to the collection of object-oriented languages. Originally planned as a programming language for consumer electronics, such as interactive cable television boxes, Java evolved into an object-oriented programming platform for developing Web applications. Java was officially launched by Sun Microsystems in 1995 and has many of the characteristics of C++, from which it derives much of its syntax. Like C++, Java can also be used for procedural programming, so it is sometimes classified as a hybrid language.

The object-oriented paradigm can be applied to a wide range of programming problems. Basically, if you can envision a problem as a set of objects that pass messages back and forth, the problem is suitable for the OO approach.

The object-oriented paradigm is cognitively similar to the way human beings perceive the real world. Using the object-oriented approach, programmers might be able to visualize the solutions to problems more easily. Facets of the object-oriented paradigm can also increase a programmer’s efficiency because encapsulation allows objects to be adapted and reused in a variety of different programs. Encapsulation refers to the process of hiding the internal details of objects and their methods. After an object is coded, it becomes a “black box,” which essentially hides its details from other objects and allows the data to be accessed using methods.

A potential disadvantage of object-oriented programs is runtime efficiency. Object-oriented programs tend to require more memory and processing resources than procedural programs. Programmers, software engineers, and system analysts can work together to weigh the tradeoffs between the OO approach and runtime efficiency.

Comprehension check. Match the beginnings of the sentences in the first column with the endings in the second column.

Vocabulary practice

1. Put the letters in the following words into the correct order.

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2. Fill in the blanks choosing from the variants given.

1. The process of hiding internal details of objects and their methods is called … .

a) encapsulation c) inheritance

b) polymorphism d) object-oriented

2. Smalltalk, Eiffel, Java, and … are all programming languages that support the object-oriented paradigm.

a) C b) C++ c) Fortran d) Ada

3. … is NOT a typical feature of an object-oriented language.

a) polymorphism c) classes

b) inheritance d) relationships

4. Object-oriented programs tend to require … memory and processing resources than procedural programs.

a) less b) more

5. Hybrid languages, such as Ada95, Visual Basic, and …, give programmers the option of using procedural and object-oriented techniques.

a) C b) C++ c) C#

6. If you can envision a problem as a set of … that pass messages back and forth, the problem is suitable for the OO approach.

a) classes b) objects

3. Match the beginnings and the endings of the sentences, and then put the sentences into the correct order.

4. Fill in the gaps in the text.

The OO paradigm allows programmers to hide the internal details of objects and their methods. This process, called ___, allows objects to be easily reused, modified, and repurposed.

Computer historians believe ___ was the first programming language to work with objects, classes, inheritance, and methods. It is a language called ___. Recently many procedural languages have been given OO capabilities. ___, which originated at the Department of Defense, was originally a procedural language, but now includes OO features. The C language was modified into a language called___, and again modified into C#. Recent versions of ___ Basic also offer programmers the option of working within the object-oriented paradigm.

Speaking. Discuss the following questions.

1. How did object-oriented languages originate?

2. Which object-oriented languages are popular today?

3. What kinds of applications are suitable for object-oriented languages?

4. What are the advantages and disadvantages of the OO paradigm?

Critical thinking. Read the article and express your opinion on the problem.

Human Factors

Today’s programming languages provide programmers with sophisticated tools for coding and testing software. Why then, are computers and computer software so often characterized as being difficult to use?

Programmer and user interface designer Alan Cooper offers an explanation and solution in his book “The Inmates Are Running the Asylum”. According to Cooper, programmers don’t intentionally create bad technology products. “Programmers aren’t evil. They work hard to make their software easy to use. Unfortunately, their frame of reference is themselves, so they only make it easy to use for other software engineers, not for normal human beings”. Cooper suggests that it is possible to create intuitive, easy-to-use technology products by devoting more time to developing detailed product specifications with the assistance of an “interactive designer” who is familiar with the psychology and habits of a typical computer user.

Clare-Marie Karat, a psychologist and IBM researcher developed

Date: 2015-01-12; view: 1970