Object Oriented Programming OOP folatpanelche.cf Zarak Shakeel. DEITEL® HOW TO PROGRAM SERIES Cover Theme The cover theme for the DEITEL® HOW TO. folatpanelche.cf There really is no shortage of books and websites describing the basics of object oriented programming. In book: Encyclopedia of Information Science and Technology, Fourth As a computer programming approach, OOP is useful such that it.
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OOP: Introduction. 1. Introduction to Object-Oriented Programming. • Objects and classes. • Abstract Data Types (ADT). • Encapsulation and information hiding. Object Oriented Programming (OOP) is an approach to program organization and Object-oriented programming is the most recent concept among. Object-oriented programming is the current cure-all — although it has been This book is not going to praise object-oriented programming or condemn the.
Lott , The intent of this book is to help the beginning designer by giving them a sequence of interesting and moderately complex exercises in OO design. This book can also help managers develop a level of comfort with the process of OO software development.
Lieberherr's method provides a new approach to OO program design that goes beyond object encapsulation to achieve more flexible interactions among objects. Chapters are self-contained, with the development of ideas moving from programming language design to environments and applications.
Kovac , The author promotes the thesis that design patterns inspired by functional programming concepts can advance object-oriented design. The book integrates the areas of object-orientation, functional programming, design patterns, and language design.
New objects can be created based on already existing objects chosen as their prototype. You may call two different objects apple and orange a fruit, if the object fruit exists, and both apple and orange have fruit as their prototype. The idea of the fruit class doesn't exist explicitly, but as the equivalence class of the objects sharing the same prototype.
The attributes and methods of the prototype are delegated to all the objects of the equivalence class defined by this prototype. The attributes and methods owned individually by the object may not be shared by other objects of the same equivalence class; e.
Only single inheritance can be implemented through the prototype. This feature is known as dynamic dispatch , and distinguishes an object from an abstract data type or module , which has a fixed static implementation of the operations for all instances.
If the call variability relies on more than the single type of the object on which it is called i. A method call is also known as message passing. It is conceptualized as a message the name of the method and its input parameters being passed to the object for dispatch. Encapsulation[ edit ] Encapsulation is an object-oriented programming concept that binds together the data and functions that manipulate the data, and that keeps both safe from outside interference and misuse.
Data encapsulation led to the important OOP concept of data hiding. If a class does not allow calling code to access internal object data and permits access through methods only, this is a strong form of abstraction or information hiding known as encapsulation.
Some languages Java, for example let classes enforce access restrictions explicitly, for example denoting internal data with the private keyword and designating methods intended for use by code outside the class with the public keyword. Methods may also be designed public, private, or intermediate levels such as protected which allows access from the same class and its subclasses, but not objects of a different class.
In other languages like Python this is enforced only by convention for example, private methods may have names that start with an underscore.
Encapsulation prevents external code from being concerned with the internal workings of an object. This facilitates code refactoring , for example allowing the author of the class to change how objects of that class represent their data internally without changing any external code as long as "public" method calls work the same way. It also encourages programmers to put all the code that is concerned with a certain set of data in the same class, which organizes it for easy comprehension by other programmers.
Encapsulation is a technique that encourages decoupling. Composition, inheritance, and delegation[ edit ] Objects can contain other objects in their instance variables; this is known as object composition. Object composition is used to represent "has-a" relationships: every employee has an address, so every Employee object has access to a place to store an Address object either directly embedded within itself, or at a separate location addressed via a pointer.
Languages that support classes almost always support inheritance. This allows classes to be arranged in a hierarchy that represents "is-a-type-of" relationships.
For example, class Employee might inherit from class Person. All the data and methods available to the parent class also appear in the child class with the same names. These will also be available in class Employee, which might add the variables "position" and "salary". This technique allows easy re-use of the same procedures and data definitions, in addition to potentially mirroring real-world relationships in an intuitive way. Rather than utilizing database tables and programming subroutines, the developer utilizes objects the user may be more familiar with: objects from their application domain.
Multiple inheritance is allowed in some languages, though this can make resolving overrides complicated. Some languages have special support for mixins , though in any language with multiple inheritance, a mixin is simply a class that does not represent an is-a-type-of relationship.
Mixins are typically used to add the same methods to multiple classes. Abstract classes cannot be instantiated into objects; they exist only for the purpose of inheritance into other "concrete" classes which can be instantiated. In Java, the final keyword can be used to prevent a class from being subclassed. The doctrine of composition over inheritance advocates implementing has-a relationships using composition instead of inheritance.
For example, instead of inheriting from class Person, class Employee could give each Employee object an internal Person object, which it then has the opportunity to hide from external code even if class Person has many public attributes or methods.
Some languages, like Go do not support inheritance at all. Delegation is another language feature that can be used as an alternative to inheritance.
Polymorphism[ edit ] Subtyping - a form of polymorphism - is when calling code can be agnostic as to which class in the supported hierarchy it is operating on - the parent class or one of its descendants. Meanwhile, the same operation name among objects in an inheritance hierarchy may behave differently.
For example, objects of type Circle and Square are derived from a common class called Shape. The Draw function for each type of Shape implements what is necessary to draw itself while calling code can remain indifferent to the particular type of Shape is being drawn. This is another type of abstraction which simplifies code external to the class hierarchy and enables strong separation of concerns. Open recursion[ edit ] In languages that support open recursion , object methods can call other methods on the same object including themselves , typically using a special variable or keyword called this or self.
This variable is late-bound ; it allows a method defined in one class to invoke another method that is defined later, in some subclass thereof.
History[ edit ] UML notation for a class. This Button class has variables for data, and functions. Through inheritance a subclass can be created as subset of the Button class. Objects are instances of a class. Terminology invoking "objects" and "oriented" in the modern sense of object-oriented programming made its first appearance at MIT in the late s and early s.
In the environment of the artificial intelligence group, as early as , "object" could refer to identified items LISP atoms with properties attributes ;   Alan Kay was later to cite a detailed understanding of LISP internals as a strong influence on his thinking in Alan Kay,  Another early MIT example was Sketchpad created by Ivan Sutherland in —61; in the glossary of the technical report based on his dissertation about Sketchpad, Sutherland defined notions of "object" and "instance" with the class concept covered by "master" or "definition" , albeit specialized to graphical interaction.
We will go through the design, coding, and testing phases of the software life cycle to illustrate the development process. Since the program we develop here is very simple, we can write it without really going through the phases. However, it is extremely important for you to get into a habit of developing a program by following the software life cycle stages. Small programs can be developed in a haphazard manner, but not large programs. We will teach you the development process with small programs first, so you will be ready to use it to create large programs later.
We will develop this program by using an incremental development technique, which will develop the program in small incremental steps. We start out with a barebones program and gradually build up the program by adding more and more code to it. At each incremental step, we design, code, and test the program before moving on to the next step. This methodical development of a program allows us to focus our attention on a single task at each step, and this reduces the chance of introducing errors into the program.
Sample Development Programs Most chapters include a sample development section that describes the process of incremental development. Problem Statement We start our development with a problem statement. The problem statement for our sample programs will be short, ranging from a sentence to a paragraph, but the problem statement for complex and advanced applications may contain many pages. Overall Plan Our first task is to map out the overall plan for development. We will identify classes necessary for the program and the steps we will follow to implement the program.