Re: Principles Of Object Oriented Programming In JavaScript Torrent

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Jul 12, 2024, 5:37:02 PM7/12/24

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Object-oriented programming (OOP) is a programming paradigm fundamental to many programming languages, including Java and C++. In this article, we'll provide an overview of the basic concepts of OOP. We'll describe three main concepts: classes and instances, inheritance, and encapsulation. For now, we'll describe these concepts without reference to JavaScript in particular, so all the examples are given in pseudocode.

Principles of Object Oriented Programming in JavaScript torrent

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After that, in JavaScript, we'll look at how constructors and the prototype chain relate to these OOP concepts, and how they differ. In the next article, we'll look at some additional features of JavaScript that make it easier to implement object-oriented programs.

Object-oriented programming is about modeling a system as a collection of objects, where each object represents some particular aspect of the system. Objects contain both functions (or methods) and data. An object provides a public interface to other code that wants to use it but maintains its own private, internal state; other parts of the system don't have to care about what is going on inside the object.

Second, although a prototype chain looks like an inheritance hierarchy and behaves like it in some ways, it's different in others. When a subclass is instantiated, a single object is created which combines properties defined in the subclass with properties defined further up the hierarchy. With prototyping, each level of the hierarchy is represented by a separate object, and they are linked together via the __proto__ property. The prototype chain's behavior is less like inheritance and more like delegation. Delegation is a programming pattern where an object, when asked to perform a task, can perform the task itself or ask another object (its delegate) to perform the task on its behalf. In many ways, delegation is a more flexible way of combining objects than inheritance (for one thing, it's possible to change or completely replace the delegate at run time).

In The Principles of Object-Oriented JavaScript, Nicholas C. Zakas thoroughly explores JavaScript's object-oriented nature, revealing the language's unique implementation of inheritance and other key characteristics. You'll learn:

Object-oriented programming (OOP) is a programming paradigm based on the concept of objects,[1] which can contain data and code: data in the form of fields (often known as attributes or properties), and code in the form of procedures (often known as methods).

Many of the most widely used programming languages (such as C++, Java,[4] Python, etc.) are multi-paradigm and they support object-oriented programming to a greater or lesser degree, typically in combination with imperative, procedural programming.

Terminology invoking "objects" in the modern sense of object-oriented programming made its first appearance at MIT in the late 1950s and early 1960s. In the environment of the artificial intelligence group, as early as 1960, "object" could refer to identified items (LISP atoms) with properties (attributes);[5][6]Alan Kay later cited a detailed understanding of LISP internals as a strong influence on his thinking in 1966, and that he used the term "object-oriented programming" in conversation as early as 1967.[1] Although sometimes called "the father of object-oriented programming",[7] Alan Kay has differentiated his notion of OO from the more conventional abstract data type notion of object, and has implied that the computer science establishment did not adopt his notion.[1] A 1976 MIT memo co-authored by Barbara Liskov lists Simula 67, CLU, and Alphard as object-oriented languages, but does not mention Smalltalk.[8]

Simula introduced important concepts that are today an essential part of object-oriented programming, such as class and object, inheritance, and dynamic binding.[12] The object-oriented Simula programming language was used mainly by researchers involved with physical modelling, such as models to study and improve the movement of ships and their content through cargo ports.[12]

In the 1970s, the first version of the Smalltalk programming language was developed at Xerox PARC by Alan Kay, Dan Ingalls and Adele Goldberg. Smalltalk-72 included a programming environment and was dynamically typed, and at first was interpreted, not compiled. Smalltalk became noted for its application of object orientation at the language-level and its graphical development environment. Smalltalk went through various versions and interest in the language grew.[13] While Smalltalk was influenced by the ideas introduced in Simula 67 it was designed to be a fully dynamic system in which classes could be created and modified dynamically.[14]

In the 1970s, Smalltalk influenced the Lisp community to incorporate object-based techniques that were introduced to developers via the Lisp machine.[citation needed] Experimentation with various extensions to Lisp (such as LOOPS and Flavors introducing multiple inheritance and mixins) eventually led to the Common Lisp Object System, which integrates functional programming and object-oriented programming and allows extension via a Meta-object protocol. In the 1980s, there were a few attempts to design processor architectures that included hardware support for objects in memory but these were not successful. Examples include the Intel iAPX 432 and the Linn Smart Rekursiv.

In 1981, Goldberg edited the August issue of Byte Magazine, introducing Smalltalk and object-oriented programming to a wider audience. In 1986, the Association for Computing Machinery organised the first Conference on Object-Oriented Programming, Systems, Languages, and Applications (OOPSLA), which was unexpectedly attended by 1,000 people. In the mid-1980s Objective-C was developed by Brad Cox, who had used Smalltalk at ITT Inc.. Bjarne Stroustrup, who had used Simula for his PhD thesis, created the object-oriented C++.[13] In 1985, Bertrand Meyer also produced the first design of the Eiffel language. Focused on software quality, Eiffel is a purely object-oriented programming language and a notation supporting the entire software lifecycle. Meyer described the Eiffel software development method, based on a small number of key ideas from software engineering and computer science, in Object-Oriented Software Construction. Essential to the quality focus of Eiffel is Meyer's reliability mechanism, Design by Contract, which is an integral part of both the method and language.

In the early and mid-1990s object-oriented programming developed as the dominant programming paradigm when programming languages supporting the techniques became widely available. These included Visual FoxPro 3.0,[15][16][17] C++,[18] and Delphi[citation needed]. Its dominance was further enhanced by the rising popularity of graphical user interfaces, which rely heavily upon object-oriented programming techniques. An example of a closely related dynamic GUI library and OOP language can be found in the Cocoa frameworks on Mac OS X, written in Objective-C, an object-oriented, dynamic messaging extension to C based on Smalltalk. OOP toolkits also enhanced the popularity of event-driven programming (although this concept is not limited to OOP).

At ETH Zürich, Niklaus Wirth and his colleagues had also been investigating such topics as data abstraction and modular programming (although this had been in common use since the 1960s or earlier, Wirth has added type checking across module boundaries). Modula-2 (1978) included both, and their succeeding design, Oberon, included a distinctive approach to object orientation, classes, and such. Inheritance is not obvious in Wirth's design since his nomenclature looks the opposite direction: It is called type extension and the viewpoint is from the parent down to the inheritor.

More recently, a number of languages have emerged that are primarily object-oriented, but that are also compatible with procedural methodology. Two such languages are Python and Ruby. Probably the most commercially important recent object-oriented languages are Java, developed by Sun Microsystems, as well as C# and Visual Basic.NET (VB.NET), both designed for Microsoft's .NET platform. Each of these two frameworks shows, in its own way, the benefit of using OOP by creating an abstraction from implementation. VB.NET and C# support cross-language inheritance, allowing classes defined in one language to subclass classes defined in the other language.