Oops

Programming paradigm based on the concept of objects

Object-oriented programming (OOP) is a programming prototype based on the concept of "objects", which can incorporate data and code: data in the grade of fields (often known as attributes or properties), and code, in the form of procedures (often known equally methods).

A feature of objects is that an object's own procedures can access and oft alter the information fields of itself (objects have a notion of this or self ). In OOP, computer programs are designed past making them out of objects that collaborate with one another.^[one] ^[2] OOP languages are various, but the most pop ones are course-based, meaning that objects are instances of classes, which also determine their types.

Many of the virtually widely used programming languages (such as C++, Coffee, Python, etc.) are multi-epitome and they back up object-oriented programming to a greater or bottom degree, typically in combination with imperative, procedural programming. Significant object-oriented languages include: Java, C++, C#, Python, R, PHP, Visual Basic.Internet, JavaScript, Ruby, Perl, SIMSCRIPT, Object Pascal, Objective-C, Sprint, Swift, Scala, Kotlin, Common Lisp, MATLAB, and Smalltalk.

History [edit]

UML note for a class. This Button form has variables for information, and functions. Through inheritance a subclass can be created as subset of the Push 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 1950s and early 1960s. In the environment of the bogus intelligence group, equally early as 1960, "object" could refer to identified items (LISP atoms) with properties (attributes);^[3] ^[4] Alan Kay later cited a detailed understanding of LISP internals as a potent influence on his thinking in 1966.^[5]

I thought of objects being like biological cells and/or private computers on a network, only able to communicate with letters (so messaging came at the very beginning – it took a while to see how to do messaging in a programming language efficiently plenty to be useful).

Alan Kay, ^[five]

Some other early MIT case was Sketchpad created by Ivan Sutherland in 1960–1961; in the glossary of the 1963 technical report based on his dissertation near Sketchpad, Sutherland defined notions of "object" and "instance" (with the course concept covered by "master" or "definition"), albeit specialized to graphical interaction.^[6] Too, an MIT ALGOL version, AED-0, established a direct link between information structures ("plexes", in that dialect) and procedures, prefiguring what were afterward termed "messages", "methods", and "member functions".^[vii] ^[viii]

Simula introduced important concepts that are today an essential role of object-oriented programming, such as form and object, inheritance, and dynamic bounden.^[9] The object-oriented Simula programming language was used mainly past researchers involved with physical modelling, such equally models to study and improve the move of ships and their content through cargo ports.^[nine]

In the 1970s, the showtime 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 beginning 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 involvement in the language grew.^[ten] While Smalltalk was influenced by the ideas introduced in Simula 67 it was designed to be a fully dynamic organisation in which classes could exist created and modified dynamically.^[11]

In the 1970s, Smalltalk influenced the Lisp community to incorporate object-based techniques that were introduced to developers via the Lisp machine. Experimentation with diverse extensions to Lisp (such as LOOPS and Flavors introducing multiple inheritance and mixins) somewhen led to the Mutual Lisp Object Organization, 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 retentivity but these were not successful. Examples include the Intel iAPX 432 and the Linn Smart Rekursiv.

In 1981, Goldberg edited the August outcome of Byte Mag, introducing Smalltalk and object-oriented programming to a wider audition. 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 one,000 people. In the mid-1980s Objective-C was adult past Brad Cox, who had used Smalltalk at ITT Inc., and Bjarne Stroustrup, who had used Simula for his PhD thesis, eventually went to create the object-oriented C++.^[10] In 1985, Bertrand Meyer also produced the first blueprint 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 primal ideas from software engineering and estimator 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 linguistic communication.

In the early on and mid-1990s object-oriented programming developed equally the dominant programming prototype when programming languages supporting the techniques became widely available. These included Visual FoxPro 3.0,^[12] ^[13] ^[14] C++,^[15] 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 issue-driven programming (although this concept is not limited to OOP).

At ETH Zürich, Niklaus Wirth and his colleagues had too been investigating such topics as information abstraction and modular programming (although this had been in common apply in the 1960s or earlier). Modula-2 (1978) included both, and their succeeding pattern, Oberon, included a distinctive approach to object orientation, classes, and such.

Object-oriented features have been added to many previously existing languages, including Ada, Bones, Fortran, Pascal, and COBOL. Adding these features to languages that were not initially designed for them often led to issues with compatibility and maintainability of code.

More recently, a number of languages have emerged that are primarily object-oriented, merely that are also compatible with procedural methodology. 2 such languages are Python and Ruby. Probably the near commercially important recent object-oriented languages are Java, developed by Sun Microsystems, as well every bit C# and Visual Basic.NET (VB.Internet), both designed for Microsoft'southward .NET platform. Each of these 2 frameworks shows, in its own way, the benefit of using OOP by creating an abstraction from implementation. VB.NET and C# support cross-linguistic communication inheritance, allowing classes divers in one language to subclass classes defined in the other language.

Features [edit]

Object-oriented programming uses objects, but not all of the associated techniques and structures are supported straight in languages that claim to back up OOP. It performs operations on operands. The features listed below are common among languages considered to be strongly class- and object-oriented (or multi-paradigm with OOP support), with notable exceptions mentioned.^[16] ^[17] ^[18] ^[19]

Shared with non-OOP languages [edit]

Variables that tin store information formatted in a pocket-size number of congenital-in data types like integers and alphanumeric characters. This may include data structures like strings, lists, and hash tables that are either born or result from combining variables using retention pointers.
Procedures – likewise known as functions, methods, routines, or subroutines – that accept input, generate output, and manipulate data. Modern languages include structured programming constructs like loops and conditionals.

Modular programming support provides the ability to group procedures into files and modules for organizational purposes. Modules are namespaced so identifiers in one module will not conflict with a process or variable sharing the aforementioned proper name in some other file or module.

Objects and classes [edit]

Languages that support object-oriented programming (OOP) typically utilise inheritance for code reuse and extensibility in the course of either classes or prototypes. Those that use classes support two principal concepts:

Classes – the definitions for the data format and available procedures for a given type or class of object; may also comprise data and procedures (known as class methods) themselves, i.east. classes contain the data members and member functions
Objects – instances of classes

Objects sometimes represent to things found in the real world. For example, a graphics program may have objects such as "circle", "square", "menu". An online shopping system might have objects such every bit "shopping cart", "client", and "product".^[20] Sometimes objects represent more abstract entities, like an object that represents an open file, or an object that provides the service of translating measurements from U.S. customary to metric.

Each object is said to be an example of a item grade (for example, an object with its name field gear up to "Mary" might exist an instance of grade Employee). Procedures in object-oriented programming are known as methods; variables are also known as fields, members, attributes, or properties. This leads to the following terms:

Class variables – belong to the class equally a whole; there is only one copy of each ane
Example variables or attributes – data that belongs to individual objects; every object has its own re-create of each one
Member variables – refers to both the form and instance variables that are defined by a item class
Grade methods – belong to the class as a whole and have access to but class variables and inputs from the procedure call
Case methods – belong to individual objects, and have access to instance variables for the specific object they are called on, inputs, and grade variables

Objects are accessed somewhat like variables with circuitous internal construction, and in many languages are effectively pointers, serving equally actual references to a single instance of said object in memory within a heap or stack. They provide a layer of abstraction which tin can exist used to divide internal from external lawmaking. External lawmaking tin employ an object by calling a specific instance method with a certain set of input parameters, read an instance variable, or write to an instance variable. Objects are created by calling a special type of method in the class known equally a constructor. A program may create many instances of the aforementioned grade as information technology runs, which operate independently. This is an easy way for the same procedures to exist used on dissimilar sets of data.

Object-oriented programming that uses classes is sometimes chosen course-based programming, while prototype-based programming does not typically use classes. As a result, significantly unlike however analogous terminology is used to define the concepts of object and instance.

In some languages classes and objects can be composed using other concepts like traits and mixins.

Class-based vs prototype-based [edit]

In grade-based languages the classes are defined beforehand and the objects are instantiated based on the classes. If two objects apple and orange are instantiated from the class Fruit, they are inherently fruits and information technology is guaranteed that you may handle them in the same way; eastward.g. a programmer can expect the existence of the aforementioned attributes such equally color or sugar_content or is_ripe.

In prototype-based languages the objects are the primary entities. No classes even exist. The prototype of an object is just some other object to which the object is linked. Every object has ane epitome link (and merely 1). New objects tin be created based on already existing objects chosen as their paradigm. You may call two unlike objects apple and orangish 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 be explicitly, merely 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 grade defined by this prototype. The attributes and methods endemic individually past the object may not be shared by other objects of the same equivalence form; east.g. the attribute sugar_content may be unexpectedly non present in apple. Just single inheritance can be implemented through the paradigm.

Dynamic acceleration/message passing [edit]

It is the responsibility of the object, not any external code, to select the procedural code to execute in response to a method call, typically by looking up the method at run fourth dimension in a table associated with the object. This feature is known as dynamic acceleration. If the call variability relies on more than the single blazon of the object on which it is called (i.due east. at least one other parameter object is involved in the method choice), ane speaks of multiple dispatch.

A method telephone call is also known every bit message passing. It is conceptualized every bit a message (the proper name of the method and its input parameters) being passed to the object for dispatch.

Information Brainchild [edit]

Data Brainchild is a pattern pattern in which data are visible simply to semantically related functions, so as to prevent misuse. The success of data abstraction leads to frequent incorporation of data hiding equally a pattern principle in object oriented and pure functional programming.

If a class does not let calling code to access internal object data and permits admission through methods just, this is a strong form of abstraction or information hiding known as brainchild. Some languages (Java, for example) let classes enforce access restrictions explicitly, for example cogent internal information with the private keyword and designating methods intended for use by code outside the form with the public keyword. Methods may also be designed public, private, or intermediate levels such as protected (which allows access from the aforementioned class and its subclasses, but not objects of a different class). In other languages (like Python) this is enforced only by convention (for instance, private methods may have names that start with an underscore).

Encapsulation [edit]

Encapsulation prevents external lawmaking from being concerned with the internal workings of an object. This facilitates code refactoring, for example allowing the writer of the class to change how objects of that course correspond their data internally without changing any external code (every bit long as "public" method calls work the same way). It also encourages programmers to put all the code that is concerned with a certain gear up 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 tin contain other objects in their example variables; this is known as object composition. For instance, an object in the Employee class might comprise (either direct or through a pointer) an object in the Accost class, in addition to its own example variables like "first_name" and "position". 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, course Employee might inherit from class Person. All the information and methods available to the parent grade also appear in the kid class with the same names. For example, course Person might define variables "first_name" and "last_name" with method "make_full_name()". These will likewise be available in class Employee, which might add together the variables "position" and "salary". This technique allows easy re-use of the same procedures and data definitions, in improver to potentially mirroring real-earth relationships in an intuitive fashion. Rather than utilizing database tables and programming subroutines, the developer utilizes objects the user may be more than familiar with: objects from their application domain.^[21]

Subclasses tin override the methods divers past superclasses. 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 just a class that does not represent an is-a-blazon-of relationship. Mixins are typically used to add the same methods to multiple classes. For example, grade UnicodeConversionMixin might provide a method unicode_to_ascii() when included in grade FileReader and class WebPageScraper, which don't share a common parent.

Abstract classes cannot be instantiated into objects; they exist only for the purpose of inheritance into other "concrete" classes that can be instantiated. In Java, the last keyword can be used to prevent a grade from being subclassed.

The doctrine of composition over inheritance advocates implementing has-a relationships using limerick 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 practise not support inheritance at all.

The "open up/closed principle" advocates that classes and functions "should be open for extension, but closed for modification".

Delegation is another language feature that can exist used every bit an alternative to inheritance.

Polymorphism [edit]

Subtyping – a form of polymorphism – is when calling code can be independent of which class in the supported hierarchy it is operating on – the parent class or one of its descendants. Meanwhile, the aforementioned functioning proper name amidst objects in an inheritance hierarchy may behave differently.

For case, objects of blazon Circle and Square are derived from a common class called Shape. The Draw office for each type of Shape implements what is necessary to draw itself while calling code tin can remain indifferent to the particular type of Shape beingness drawn.

This is another blazon of abstraction that simplifies code external to the form hierarchy and enables stiff separation of concerns.

Open up 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-jump; information technology allows a method defined in one class to invoke another method that is divers subsequently, in some subclass thereof.

OOP languages [edit]

Simula (1967) is by and large accepted as beingness the starting time language with the principal features of an object-oriented linguistic communication. It was created for making simulation programs, in which what came to be chosen objects were the most important information representation. Smalltalk (1972 to 1980) is another early on example, and the i with which much of the theory of OOP was developed. Concerning the degree of object orientation, the following distinctions can be made:

Languages called "pure" OO languages, considering everything in them is treated consistently as an object, from primitives such as characters and punctuation, all the mode up to whole classes, prototypes, blocks, modules, etc. They were designed specifically to facilitate, fifty-fifty enforce, OO methods. Examples: Ruby, Scala, Smalltalk, Eiffel, Emerald,^[22] JADE, Self, Raku.
Languages designed mainly for OO programming, but with some procedural elements. Examples: Java, Python, C++, C#, Delphi/Object Pascal, VB.Net.
Languages that are historically procedural languages, but have been extended with some OO features. Examples: PHP, Perl, Visual Basic (derived from Bones), MATLAB, COBOL 2002, Fortran 2003, ABAP, Ada 95, Pascal.
Languages with most of the features of objects (classes, methods, inheritance), just in a distinctly original grade. Examples: Oberon (Oberon-1 or Oberon-ii).
Languages with abstract information type support which may be used to resemble OO programming, just without all features of object-orientation. This includes object-based and epitome-based languages. Examples: JavaScript, Lua, Modula-2, CLU.
Chameleon languages that back up multiple paradigms, including OO. Tcl stands out amongst these for TclOO, a hybrid object system that supports both prototype-based programming and class-based OO.

OOP in dynamic languages [edit]

In recent years, object-oriented programming has become especially popular in dynamic programming languages. Python, PowerShell, Ruby and Groovy are dynamic languages built on OOP principles, while Perl and PHP have been adding object-oriented features since Perl 5 and PHP 4, and ColdFusion since version 6.

The Document Object Model of HTML, XHTML, and XML documents on the Internet has bindings to the popular JavaScript/ECMAScript language. JavaScript is perhaps the all-time known image-based programming language, which employs cloning from prototypes rather than inheriting from a form (dissimilarity to course-based programming). Another scripting language that takes this approach is Lua.

OOP in a network protocol [edit]

The letters that menstruation between computers to asking services in a client-server environs can exist designed as the linearizations of objects divers past course objects known to both the client and the server. For example, a unproblematic linearized object would consist of a length field, a lawmaking point identifying the form, and a data value. A more complex case would be a command consisting of the length and code point of the command and values consisting of linearized objects representing the control's parameters. Each such control must be directed by the server to an object whose form (or superclass) recognizes the command and is able to provide the requested service. Clients and servers are all-time modeled every bit complex object-oriented structures. Distributed Data Management Architecture (DDM) took this approach and used class objects to define objects at iv levels of a formal bureaucracy:

Fields defining the information values that form messages, such as their length, lawmaking betoken and information values.
Objects and collections of objects similar to what would be found in a Smalltalk program for messages and parameters.
Managers similar to IBM i Objects, such every bit a directory to files and files consisting of metadata and records. Managers conceptually provide memory and processing resource for their contained objects.
A customer or server consisting of all the managers necessary to implement a full processing surroundings, supporting such aspects as directory services, security and concurrency control.

The initial version of DDM defined distributed file services. It was after extended to exist the foundation of Distributed Relational Database Architecture (DRDA).

Design patterns [edit]

Challenges of object-oriented pattern are addressed by several approaches. Virtually common is known as the design patterns codified by Gamma et al.. More broadly, the term "design patterns" can be used to refer to whatsoever full general, repeatable, solution design to a commonly occurring trouble in software design. Some of these commonly occurring problems have implications and solutions detail to object-oriented development.

Inheritance and behavioral subtyping [edit]

Information technology is intuitive to assume that inheritance creates a semantic "is a" relationship, and thus to infer that objects instantiated from subclasses can always be safely used instead of those instantiated from the superclass. This intuition is unfortunately false in about OOP languages, in item in all those that allow mutable objects. Subtype polymorphism every bit enforced by the type checker in OOP languages (with mutable objects) cannot guarantee behavioral subtyping in whatsoever context. Behavioral subtyping is undecidable in general, and then it cannot be implemented by a program (compiler). Form or object hierarchies must exist carefully designed, considering possible incorrect uses that cannot be detected syntactically. This issue is known as the Liskov exchange principle.

Gang of Four blueprint patterns [edit]

Blueprint Patterns: Elements of Reusable Object-Oriented Software is an influential book published in 1994 by Erich Gamma, Richard Captain, Ralph Johnson, and John Vlissides, often referred to humorously as the "Gang of 4". Along with exploring the capabilities and pitfalls of object-oriented programming, it describes 23 common programming bug and patterns for solving them. As of April 2007, the book was in its 36th press.

The volume describes the following patterns:

Creational patterns (v): Manufactory method pattern, Abstruse factory design, Singleton pattern, Architect pattern, Image pattern
Structural patterns (7): Adapter pattern, Bridge design, Composite blueprint, Decorator design, Facade pattern, Flyweight design, Proxy design
Behavioral patterns (11): Chain-of-responsibility pattern, Command pattern, Interpreter pattern, Iterator design, Mediator blueprint, Memento pattern, Observer blueprint, State pattern, Strategy blueprint, Template method pattern, Company pattern

Object-orientation and databases [edit]

Both object-oriented programming and relational database management systems (RDBMSs) are extremely common in software today^[update]. Since relational databases don't store objects directly (though some RDBMSs accept object-oriented features to approximate this), there is a general need to bridge the two worlds. The problem of bridging object-oriented programming accesses and data patterns with relational databases is known as object-relational impedance mismatch. At that place are a number of approaches to cope with this problem, only no full general solution without downsides.^[23] One of the most common approaches is object-relational mapping, every bit constitute in IDE languages such as Visual FoxPro and libraries such as Java Data Objects and Crimson on Track' ActiveRecord.

At that place are likewise object databases that can exist used to supervene upon RDBMSs, but these have not been as technically and commercially successful as RDBMSs.

Real-world modeling and relationships [edit]

OOP can be used to associate existent-world objects and processes with digital counterparts. Nevertheless, not everyone agrees that OOP facilitates directly existent-globe mapping (see Criticism section) or that real-world mapping is even a worthy goal; Bertrand Meyer argues in Object-Oriented Software Structure ^[24] that a program is not a model of the world but a model of some part of the world; "Reality is a cousin twice removed". At the same fourth dimension, some principal limitations of OOP have been noted.^[25] For example, the circumvolve-ellipse problem is difficult to handle using OOP's concept of inheritance.

Notwithstanding, Niklaus Wirth (who popularized the aphorism now known as Wirth's constabulary: "Software is getting slower more apace than hardware becomes faster") said of OOP in his newspaper, "Adept Ideas through the Looking Glass", "This paradigm closely reflects the structure of systems 'in the real world', and it is therefore well suited to model complex systems with complex behaviours"^[26] (contrast Kiss principle).

Steve Yegge and others noted that natural languages lack the OOP approach of strictly prioritizing things (objects/nouns) before deportment (methods/verbs).^[27] This problem may cause OOP to endure more convoluted solutions than procedural programming.^[28]

OOP and control flow [edit]

OOP was developed to increase the reusability and maintainability of source lawmaking.^[29] Transparent representation of the command flow had no priority and was meant to exist handled past a compiler. With the increasing relevance of parallel hardware and multithreaded coding, developing transparent control flow becomes more important, something difficult to reach with OOP.^[thirty] ^[31] ^[32] ^[33]

Responsibility- vs. data-driven blueprint [edit]

Responsibleness-driven design defines classes in terms of a contract, that is, a class should exist divers around a responsibility and the information that it shares. This is assorted by Wirfs-Brock and Wilkerson with data-driven pattern, where classes are divers around the data-structures that must be held. The authors hold that responsibility-driven design is preferable.

SOLID and GRASP guidelines [edit]

SOLID is a mnemonic invented by Michael Feathers which spells out five software engineering design principles:

Single responsibility principle
Open/airtight principle
Liskov substitution principle
Interface segregation principle
Dependency inversion principle

GRASP (General Responsibility Assignment Software Patterns) is another set of guidelines advocated by Craig Larman.

Criticism [edit]

The OOP paradigm has been criticised for a number of reasons, including non coming together its stated goals of reusability and modularity,^[34] ^[35] and for overemphasizing one attribute of software design and modeling (information/objects) at the expense of other of import aspects (computation/algorithms).^[36] ^[37]

Luca Cardelli has claimed that OOP code is "intrinsically less efficient" than procedural lawmaking, that OOP can accept longer to compile, and that OOP languages accept "extremely poor modularity properties with respect to course extension and modification", and tend to be extremely complex.^[34] The latter point is reiterated by Joe Armstrong, the principal inventor of Erlang, who is quoted as saying:^[35]

The problem with object-oriented languages is they've got all this implicit environment that they acquit effectually with them. Y'all wanted a assistant just what you got was a gorilla property the banana and the entire jungle.

A report by Potok et al. has shown no significant deviation in productivity between OOP and procedural approaches.^[38]

Christopher J. Date stated that critical comparison of OOP to other technologies, relational in particular, is difficult because of lack of an agreed-upon and rigorous definition of OOP;^[39] however, Date and Darwen have proposed a theoretical foundation on OOP that uses OOP as a kind of customizable type system to support RDBMS.^[twoscore]

In an article Lawrence Krubner claimed that compared to other languages (LISP dialects, functional languages, etc.) OOP languages have no unique strengths, and inflict a heavy brunt of unneeded complexity.^[41]

Alexander Stepanov compares object orientation unfavourably to generic programming:^[36]

I find OOP technically unsound. It attempts to decompose the world in terms of interfaces that vary on a single type. To bargain with the existent problems you lot need multisorted algebras — families of interfaces that span multiple types. I find OOP philosophically unsound. It claims that everything is an object. Fifty-fifty if it is true it is not very interesting — maxim that everything is an object is saying nothing at all.

Paul Graham has suggested that OOP's popularity within large companies is due to "large (and oft changing) groups of mediocre programmers". According to Graham, the subject imposed by OOP prevents any one developer from "doing likewise much harm".^[42]

Leo Brodie has suggested a connection between the standalone nature of objects and a tendency to duplicate code^[43] in violation of the don't repeat yourself principle^[44] of software development.

Steve Yegge noted that, as opposed to functional programming:^[45]

Object Oriented Programming puts the Nouns first and foremost. Why would you go to such lengths to put one part of speech on a pedestal? Why should one kind of concept accept precedence over another? Information technology'due south not as if OOP has suddenly made verbs less important in the style nosotros actually think. It's a strangely skewed perspective.

Rich Hickey, creator of Clojure, described object systems every bit overly simplistic models of the existent world. He emphasized the inability of OOP to model time properly, which is getting increasingly problematic as software systems become more concurrent.^[37]

Eric S. Raymond, a Unix programmer and open up-source software advocate, has been disquisitional of claims that nowadays object-oriented programming as the "One True Solution", and has written that object-oriented programming languages tend to encourage thickly layered programs that destroy transparency.^[46] Raymond compares this unfavourably to the arroyo taken with Unix and the C programming language.^[46]

Rob State highway, a developer involved in the creation of UTF-8 and Go, has called object-oriented programming "the Roman numerals of computing"^[47] and has said that OOP languages often shift the focus from data structures and algorithms to types.^[48] Furthermore, he cites an instance of a Java professor whose "idiomatic" solution to a problem was to create half-dozen new classes, rather than to simply use a lookup table.^[49]

Formal semantics [edit]

Objects are the run-time entities in an object-oriented system. They may represent a person, a identify, a bank account, a table of information, or whatever item that the programme has to handle.

In that location accept been several attempts at formalizing the concepts used in object-oriented programming. The following concepts and constructs accept been used as interpretations of OOP concepts:

co algebraic data types^[fifty]
recursive types
encapsulated land
inheritance
records are ground for understanding objects if function literals can be stored in fields (like in functional-programming languages), only the actual calculi demand exist considerably more than complex to contain essential features of OOP. Several extensions of System F_<: that deal with mutable objects take been studied;^[51] these allow both subtype polymorphism and parametric polymorphism (generics)

Attempts to observe a consensus definition or theory behind objects accept non proven very successful (yet, see Abadi & Cardelli, A Theory of Objects ^[51] for formal definitions of many OOP concepts and constructs), and often diverge widely. For example, some definitions focus on mental activities, and some on program structuring. One of the simpler definitions is that OOP is the act of using "map" data structures or arrays that can incorporate functions and pointers to other maps, all with some syntactic and scoping sugar on summit. Inheritance tin be performed by cloning the maps (sometimes chosen "prototyping").

See as well [edit]

Comparison of programming languages (object-oriented programming)
Comparison of programming paradigms
Component-based software engineering science
Blueprint by contract
Object clan
Object database
Object model reference
Object modeling language
Object-oriented analysis and design
Object-relational impedance mismatch (and The Tertiary Manifesto)
Object-relational mapping

Systems [edit]

CADES
Common Object Request Broker Architecture (CORBA)
Distributed Component Object Model
Distributed Data Management Architecture
Jeroo

Modeling languages [edit]

IDEF4
Interface clarification language
Lepus3
UML

References [edit]

^ Kindler, E.; Krivy, I. (2011). "Object-Oriented Simulation of systems with sophisticated control". International Journal of General Systems: 313–343.
^ Lewis, John; Loftus, William (2008). Java Software Solutions Foundations of Programming Blueprint 6th ed. Pearson Education Inc. ISBN978-0-321-53205-three. , section 1.6 "Object-Oriented Programming"
^ McCarthy, J.; Brayton, R.; Edwards, D.; Fox, P.; Hodes, L.; Luckham, D.; Maling, K.; Park, D.; Russell, S. (March 1960). "LISP I Programmers Manual" (PDF). Boston, Massachusetts: Artificial Intelligence Grouping, Grand.I.T. Ciphering Center and Enquiry Laboratory: 88f. Archived from the original (PDF) on 17 July 2010. In the local G.I.T. patois, association lists [of atomic symbols] are also referred to every bit "belongings lists", and diminutive symbols are sometimes called "objects".
^ McCarthy, John; Abrahams, Paul W.; Edwards, Daniel J.; Hart, swapnil d.; Levin, Michael I. (1962). LISP one.5 Programmer'due south Manual. MIT Printing. p. 105. ISBN978-0-262-13011-0. Object — a synonym for diminutive symbol
^ ^a ^b "Dr. Alan Kay on the Pregnant of "Object-Oriented Programming"". 2003. Retrieved 11 February 2010.
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External links [edit]

Introduction to Object Oriented Programming Concepts (OOP) and More by L.West.C. Nirosh
Word on Cons of OOP
OOP Concepts (Java Tutorials)

leehouree.blogspot.com

Source: https://en.wikipedia.org/wiki/Object-oriented_programming