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Object Orientation has become more and more important in the last years. Object oriented programming was designed for re-use of codes. It is a type of programming in which programmers define not only the data structure, but also the types of operations that can be applied to the data structure. In this way, the data structure becomes an object that includes both data and functions. In addition, programmers can create relationships between one object and another. For example, objects can inherit characteristics from other objects. One of the principal advantages of object-oriented programming techniques over procedural programming techniques is that they enable programmers to create modules that do not need to be changed when a new type of object is added. A programmer can simply create a new object that inherits many of its features from existing objects. This makes object-oriented programs easier to modify.
Object oriented language uses the following concepts
Classes, Objects, Instance variables and Methods.
Basically everything in object orientation is considered an object, except for the primitive data types: There are mainly three groups of primitive data types: numeric types, Boolean types and arrays. Objects contain attributes and methods.
The attributes of an object are just like Adjectives in the English language. The attributes describe the objects like adjectives describe the nouns. A class is determined by common attributes, all objects falling under this category of common attribute belong to that class.
Methods are like verbs, they describe the action or task performed by the object Since objects are the fundamental building blocks they can inherit attributes and methods from their parent class. Objects can also collaborate with each other.
Objects can have: public interphase, private interphase.
If there is already a class which can respond to a bunch of different messages, and if you wanted to make a new, similar class which adds just a couple of more messages you do not have to re-write the entire class. All you need to do is create a subclass of the original class. This new class inherits all the existing messages, and therefore, all the behavior of the original class. The original class is called the parent class, or superclass, of the new class. Some more jargon-- a subclass is said to be a specialization of its superclass, and the conversely a superclass a generalization of its subclasses. Inheritance also promotes reuse. You don't have to start from scratch when you write a new program. You can simply reuse an existing repertoire of classes that have behaviors similar to what you need in the new program. Much of the art of object-oriented programming is determining the best way to divide a program into an economical set of classes. In addition to speeding development time, proper class construction and reuse results in far fewer lines of code, which translates to less bugs and lower maintenance costs.
There are almost two dozen major object-oriented programming languages in use today. But the leading commercial object-oriented languages are far fewer in number. These are:
C++, Smalltalk, Java
C++ is an object-oriented version of C. It is compatible with C, so that existing C code can be incorporated into C++ programs. C++ programs are fast and efficient, qualities which helped make C an extremely popular programming language. It sacrifices some flexibility in order to remain efficient, however. C++ uses compile-time binding, which means that the programmer must specify the specific class of an object, or at the very least, the most general class that an object can belong to. This makes for high run-time efficiency and small code size, but it trades off some of the power to reuse classes. C++ has become so popular that most new C compilers are actually C/C++ compilers. However, to take full advantage of object-oriented programming, one must program in C++, not C. This can often be a major problem for experienced C programmers. Many programmers think they are coding in C++, but instead are only using a small part of the
language's object-oriented power.
Smalltalk is a pure object-oriented language. While C++ makes some practical compromises to ensure fast execution and small code size, Smalltalk makes none. It uses run-time binding, which means that nothing about the type of an object need to be known before
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Object-oriented programming languages, Smalltalk, VisualWorks, Object-oriented programming, IBM VisualAge, Objective-C, Class, Visual Smalltalk Enterprise, Class browser
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