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Ruby is an interpreted,
high-level High-level and low-level, as technical terms, are used to classify, describe and point to specific Objective (goal), goals of a systematic operation; and are applied in a wide range of contexts, such as, for instance, in domains as widely varied as ...
,
general-purpose programming language In computer software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This is in contrast to Computer hardware, physical hardware, from which the system is bu ...
which supports multiple
programming paradigm Programming paradigms are a way to classify programming languages based on their features. Languages can be classified into multiple paradigms. Some paradigms are concerned mainly with implications for the execution model of the language, suc ...
s. It was designed with an emphasis on programming productivity and simplicity. In ruby, everything is an object, including
primitive data type In computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as practical techniques for their application. Computer science is the study of Algori ...
s. It was developed in the mid-1990s by
Yukihiro "Matz" Matsumoto
Yukihiro
in
Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an in ...

Japan
. Ruby is
dynamically typed In programming language A programming language is a formal language comprising a Instruction set architecture, set of instructions that produce various kinds of Input/output, output. Programming languages are used in computer programming to i ...
and uses
garbage collection Waste collection is a part of the process of waste management. It is the transfer of solid waste from the point of use and disposal to the point of list of waste treatment technologies, treatment or landfill. Waste collection also includes the ...
and
just-in-time compilation In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softwar ...
. It supports multiple programming paradigms, including procedural,
object-oriented Object-oriented programming (OOP) is a programming paradigm Program, programme, programmer, or programming may refer to: Business and management * Program management, the process of managing several related projects * Time management * P ...
, and
functional programming In computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as practical techniques for their application. Computer science is the study of , ...
. According to the creator, Ruby was influenced by
Perl Perl is a family of two high-level High-level and low-level, as technical terms, are used to classify, describe and point to specific Objective (goal), goals of a systematic operation; and are applied in a wide range of contexts, such as, for ...
,
Smalltalk Smalltalk is an , . Smalltalk was created as the language underpinning the "new world" of computing exemplified by "human–computer symbiosis". It was designed and created in part for al use, specifically for , at the Learning Research Group ...

Smalltalk
, Eiffel,
Ada Ada may refer to: Places Africa * Ada Foah Ada Foah is a town on the southeast coast of Ghana, where the Volta River meets the Atlantic Ocean. The town is located along the Volta River, off of the Accra-Aflao motorway. Known for Palm tree, pal ...
,
BASIC BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming language In computer science Computer science deals with the theoretical foundations of information, algorithms and the ar ...

BASIC
, and
Lisp Lisp (historically LISP) is a family of programming language A programming language is a formal language comprising a Instruction set architecture, set of instructions that produce various kinds of Input/output, output. Programming languages ...
.


History


Early concept

Matsumoto has said that Ruby was conceived in 1993. In a 1999 post to the ''ruby-talk'' mailing list, he describes some of his early ideas about the language: Matsumoto describes the design of Ruby as being like a simple
Lisp Lisp (historically LISP) is a family of programming language A programming language is a formal language comprising a Instruction set architecture, set of instructions that produce various kinds of Input/output, output. Programming languages ...
language at its core, with an object system like that of Smalltalk, blocks inspired by
higher-order function In mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ...
s, and practical utility like that of Perl. The name "Ruby" originated during an online chat session between Matsumoto and Keiju Ishitsuka on February 24, 1993, before any code had been written for the language. Initially two names were proposed: "
Coral Corals are marine invertebrates Marine invertebrates are the invertebrates that live in marine habitats. Invertebrate is a blanket term that includes all animals apart from the vertebrate members of the chordate phylum. Invertebrates lack a vert ...

Coral
" and "
Ruby A ruby is a pink to blood-red coloured gemstone A gemstone (also called a gem, fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewellery, jewelry or othe ...

Ruby
". Matsumoto chose the latter in a later e-mail to Ishitsuka. Matsumoto later noted a factor in choosing the name "Ruby" – it was the
birthstone A birthstone is a gemstone A gemstone (also called a fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound wi ...
of one of his colleagues.


Early releases

The first public release of Ruby 0.95 was announced on Japanese domestic
newsgroup A Usenet newsgroup is a Software repository, repository usually within the Usenet system, for messages Posting style, posted from users in different locations using the Internet. They are discussion groups and are not devoted to publishing news. N ...
s on December 21, 1995. Subsequently, three more versions of Ruby were released in two days. The release coincided with the launch of the ''ruby-list'' mailing list, which was the first mailing list for the new language. Already present at this stage of development were many of the features familiar in later releases of Ruby, including
object-oriented Object-oriented programming (OOP) is a programming paradigm Program, programme, programmer, or programming may refer to: Business and management * Program management, the process of managing several related projects * Time management * P ...
design,
classes Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differently f ...
with inheritance,
mixin In object-oriented programming languages, a mixin (or mix-in) is a class that contains methods for use by other classes without having to be the parent class of those other classes. How those other classes gain access to the mixin's methods depen ...
s,
iterator In computer programming, an iterator is an object (computing), object that enables a programmer to traverse a Container (data structure), container, particularly List (abstract data type), lists. Various types of iterators are often provided via a ...
s, closures,
exception handling In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithm of an algorithm (Euclid's algorithm) for calculating the greatest commo ...
and
garbage collection Waste collection is a part of the process of waste management. It is the transfer of solid waste from the point of use and disposal to the point of list of waste treatment technologies, treatment or landfill. Waste collection also includes the ...
. Following the release of Ruby 0.95 in 1995, several stable versions of Ruby were released in the following years: * Ruby 1.0: December 25, 1996 * Ruby 1.2: December 1998 * Ruby 1.4: August 1999 * Ruby 1.6: September 2000 In 1997, the first article about Ruby was published on the Web. In the same year, Matsumoto was hired by netlab.jp to work on Ruby as a full-time developer. In 1998, the Ruby Application Archive was launched by Matsumoto, along with a simple English-language homepage for Ruby. In 1999, the first English language mailing list ''ruby-talk'' began, which signaled a growing interest in the language outside Japan. In this same year, Matsumoto and Keiju Ishitsuka wrote the first book on Ruby, ''The Object-oriented Scripting Language Ruby'' (オブジェクト指向スクリプト言語 Ruby), which was published in
Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an in ...

Japan
in October 1999. It would be followed in the early 2000s by around 20 books on Ruby published in Japanese. By 2000, Ruby was more popular than Python in Japan. In September 2000, the first English language book ''
Programming Ruby ''Programming Ruby'' is a book about the Ruby programming language by Dave Thomas (programmer), Dave Thomas and Andy Hunt (author), Andrew Hunt, authors of ''The Pragmatic Programmer''. In the Ruby community, it is commonly known as "The PickAxe" b ...
'' was printed, which was later freely released to the public, further widening the adoption of Ruby amongst English speakers. In early 2002, the English-language ''ruby-talk'' mailing list was receiving more messages than the Japanese-language ''ruby-list'', demonstrating Ruby's increasing popularity in the non-Japanese speaking world.


Ruby 1.8 and 1.9

Ruby 1.8 was initially released August 2003, was stable for a long time, and was retired June 2013. Although deprecated, there is still code based on it. Ruby 1.8 is only partially compatible with Ruby 1.9. Ruby 1.8 has been the subject of several industry standards. The language specifications for Ruby were developed by the Open Standards Promotion Center of the Information-Technology Promotion Agency (a
Japanese government The is the central government of Japan , image_flag = Flag of Japan.svg , alt_flag = Centered deep red circle on a white rectangle , image_coat = Imperial Seal of Japan.svg , alt ...
agency) for submission to the
Japanese Industrial Standards Committee The is a standards organization A standards organization, standards body, standards developing organization (SDO), or standards setting organization (SSO) is an organization whose primary function is developing, coordinating, promulgating, revisi ...
(JISC) and then to the
International Organization for Standardization The International Organization for Standardization (ISO ) is an international standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization develops and publish ...
(ISO). It was accepted as a Japanese Industrial Standard (JIS X 3017) in 2011 and an international standard ( ISO/IEC 30170) in 2012. Around 2005, interest in the Ruby language surged in tandem with
Ruby on Rails Ruby on Rails, or Rails, is a server-side In the client–server model Client-server model is a distributed application Distributed computing is a field of computer science Computer science deals with the theoretical foundations of ...
, a
web framework A web framework (WF) or web application framework (WAF) is a software framework that is designed to support the development of web applications including web services, web resources, and web APIs. Web frameworks provide a standard way to build an ...
written in Ruby. Rails is frequently credited with increasing awareness of Ruby. Effective with Ruby 1.9.3, released October 31, 2011, Ruby switched from being dual-licensed under the Ruby License and the GPL to being dual-licensed under the Ruby License and the two-clause BSD license. Adoption of 1.9 was slowed by changes from 1.8 that required many popular third party
gems A gemstone (also called a fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Ea ...
to be rewritten. Ruby 1.9 introduces many significant changes over the 1.8 series. Examples include: * block local variables (variables that are local to the
block Block or blocked may refer to: Arts, entertainment and media Broadcasting * Block programming, the result of a programming strategy in broadcasting * W242BX, a radio station licensed to Greenville, South Carolina, United States known as ''96.3 t ...
in which they are declared) * an additional
lambda Lambda (; uppercase , lowercase ; el, λάμ(β)δα, ''lám(b)da'') is the 11th letter of the Greek alphabet, representing the sound Dental, alveolar and postalveolar lateral approximants, /l/. In the system of Greek numerals, lambda has a ...
syntax: * an additional
Hash Hash, hashes, hash mark, or hashing may refer to: Substances * Hash (food), a coarse mixture of ingredients * Hash, a nickname for hashish, a cannabis product Hash mark *Hash mark (sports), a marking on hockey rinks and gridiron football fields ...
literal syntax using colons for symbol keys: * per-string
character encoding Character encoding is the process of assigning numbers to graphical Graphics (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country ...
s are supported * new socket API (
IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic ...

IPv6
support) * require_relative import security


Ruby 2

Ruby 2.0 was intended to be fully backward compatible with Ruby 1.9.3. As of the official 2.0.0 release on February 24, 2013, there were only five known (minor) incompatibilities. Ruby 2.0 added several new features, including: * method keyword arguments, * a new method, Module#prepend, for extending a class, * a new literal for creating an array of symbols, * new API for the
lazy evaluation In programming language theory Programming language theory (PLT) is a branch of computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as pract ...
of Enumerables, and * a new convention of using #to_h to convert objects to Hashes. Starting with 2.1.0, Ruby's versioning policy changed to be more similar to
semantic versioning Software versioning is the process of assigning either unique ''version names'' or unique ''version numbers'' to unique states of computer software Software is a collection of Instruction (computer science), instructions and data (computing), ...
. Ruby 2.2.0 includes speed-ups, bugfixes, and library updates and removes some deprecated APIs. Most notably, Ruby 2.2.0 introduces changes to memory handling an incremental garbage collector, support for garbage collection of symbols and the option to compile directly against jemalloc. It also contains experimental support for using vfork(2) with system() and spawn(), and added support for the
Unicode Unicode, formally the Unicode Standard, is an information technology Technical standard, standard for the consistent character encoding, encoding, representation, and handling of Character (computing), text expressed in most of the world's wri ...

Unicode
7.0 specification. Since version 2.2.1, Ruby MRI performance on PowerPC64 was improved. Features that were made obsolete or removed include callcc, the DL library, Digest::HMAC, lib/rational.rb, lib/complex.rb, GServer, Logger::Application as well as various C API functions. Ruby 2.3.0 includes many performance improvements, updates, and bugfixes including changes to Proc#call, Socket and IO use of exception keywords, Thread#name handling, default passive Net::FTP connections, and Rake being removed from stdlib. Other notable changes include: * The ability to mark all
string literal A string literal or anonymous string is a type of literal Literal may refer to: * Interpretation of legal concepts: ** Strict constructionism ** The plain meaning rule (a.k.a. "literal rule") * Literal (mathematical logic), certain logical r ...
s as frozen by default with a consequently large performance increase in string operations. * Hash comparison to allow direct checking of key/value pairs instead of just keys. * A new safe navigation operator &. that can ease nil handling (e.g. instead of , we can use if obj&.foo&.bar). * The ''did_you_mean'' gem is now bundled by default and required on startup to automatically suggest similar name matches on a ''NameError'' or ''NoMethodError''. * ''Hash#dig'' and ''Array#dig'' to easily extract deeply nested values (e.g. given , the value ''Foo Baz'' can now be retrieved by profile.dig(:social, :wikipedia, :name)). * .grep_v(regexp) which will match all negative examples of a given regular expression in addition to other new features. Ruby 2.4.0 includes performance improvements to hash table, Array#max, Array#min, and instance variable access. Other notable changes include: * Binding#irb: Start a REPL session similar to binding.pry * Unify ''Fixnum'' and ''Bignum'' into ''Integer'' class * String supports Unicode case mappings, not just ASCII * A new method, Regexp#match?, which is a faster boolean version of Regexp#match * Thread deadlock detection now shows threads with their backtrace and dependency A few notable changes in Ruby 2.5.0 include ''rescue'' and ''ensure'' statements automatically use a surrounding ''do-end'' block (less need for extra ''begin-end'' blocks), method-chaining with ''yield_self'', support for branch coverage and method coverage measurement, and easier Hash transformations with ''Hash#slice'' and ''Hash#transform_keys'' On top of that come a lot of performance improvements like faster block passing (3 times faster), faster Mutexes, faster ERB templates and improvements on some concatenation methods. A few notable changes in Ruby 2.6.0 include an experimental just-in-time compiler (JIT), and ''RubyVM::AbstractSyntaxTree'' (experimental). A few notable changes in Ruby 2.7.0 include pattern Matching (experimental), REPL improvements, a compaction GC, and separation of positional and keyword arguments.


Ruby 3

Ruby 3.0.0 was released on Christmas Day in 2020. It is known as Ruby 3x3 which means that programs would run three times faster in Ruby 3.0 comparing to Ruby 2.0. and some had already implemented in intermediate releases on the road from 2 to 3. To achieve 3x3, Ruby 3 equips with MJIT, a Just-In-Time Compiler, to make programs faster, but it is still not ready for optimizing workloads like Ruby on Rails and programmers have to wait for Ruby 3.1 for further improvement. MJIT is disabled by default and could be enabled by flags at runtime. Another goal of Ruby 3.0 is to improve concurrency and two more utilities Fibre Scheduler, and experimental Ractor facilitate the goal. Ractor is light-weight and thread-safe as it is achieved by exchanging messages rather than shared objects. Ruby 3.0 introduces RBS language to describe the types of Ruby programs for
static analysis Static analysis, static projection, or static scoring is a simplified analysis wherein the effect of an immediate change to a system is calculated without regard to the longer-term response of the system to that change. If the short-term effect is ...
. It is separated from general Ruby programs. There are some syntax enhancements and library changes in Ruby 3.0 as well. Ruby 3.1 was released on Christmas Day in 2021. It includes YJIT, a new Just-In-Time Compiler developed by
Shopify Shopify Inc. is a Canadian multinational e-commerce E-commerce (electronic commerce) is the activity of electronically buying or selling of products on online services or over the Internet The Internet (Capitalization of Internet, ...
, to enhance the performance of real world business applications. A new
debugger A debugger or debugging tool is a computer program In imperative programming, a computer program is a sequence of instructions in a programming language that a computer can execute or interpret. In declarative programming, a ''computer progra ...

debugger
is also included. There are some syntax enhancements and other improvements in this release. Network libraries for
FTP The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data c ...

FTP
,
SMTP The Simple Mail Transfer Protocol (SMTP) is an internet standard An Internet Standard in computer network engineering refers to the normative specification of a technology that is appropriate for the Internet. Internet Standards allow interoper ...
,
IMAP In computing, the Internet Message Access Protocol (IMAP) is an Internet standard An Internet Standard in computer network engineering refers to the normative specification of a technology that is appropriate for the Internet. Internet Standard ...
, and
POP Pop or POP may refer to: Places * Gregorio Luperón International Airport (IATA code POP), Puerto Plata, Dominican Republic * Pop, a tributary of the river Jijia in eastern Romania * Poppleton railway station (station code), York, England People ...
are moved from default gems to bundled gems.


Table of versions


Semantics and philosophy

Matsumoto has said that Ruby is designed for programmer productivity and fun, following the principles of good
user interface In the industrial design Industrial design is a process of design A design is a plan or specification for the construction of an object or system or for the implementation of an activity or process, or the result of that plan or specificati ...
design. At a Google Tech Talk in 2008 Matsumoto further stated, "I hope to see Ruby help every programmer in the world to be productive, and to enjoy programming, and to be happy. That is the primary purpose of Ruby language." He stresses that systems design needs to emphasize human, rather than computer, needs: Matsumoto has said his primary design goal was to make a language that he himself enjoyed using, by minimizing programmer work and possible confusion. He has said that he had not applied the
principle of least astonishment The principle of least astonishment (POLA), aka principle of least surprise (alternatively a law or rule), applies to user interface and software design, software design. It proposes that a component of a system should behave in a way that most user ...
(POLA) to the design of Ruby; in a May 2005 discussion on the newsgroup comp.lang.ruby, Matsumoto attempted to distance Ruby from POLA, explaining that because any design choice will be surprising to someone, he uses a personal standard in evaluating surprise. If that personal standard remains consistent, there would be few surprises for those familiar with the standard. Matsumoto defined it this way in an interview: Ruby is
object-oriented Object-oriented programming (OOP) is a programming paradigm Program, programme, programmer, or programming may refer to: Business and management * Program management, the process of managing several related projects * Time management * P ...
: every value is an object, including classes and instances of types that many other languages designate as primitives (such as
integers An integer (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of t ...
, booleans, and " null"). Variables always hold references to objects. Every
function Function or functionality may refer to: Computing * Function key A function key is a key on a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern comp ...
is a
method Method ( grc, μέθοδος, methodos) literally means a pursuit of knowledge, investigation, mode of prosecuting such inquiry, or system. In recent centuries it more often means a prescribed process for completing a task. It may refer to: *Scien ...
and methods are always called on an object. Methods defined at the top level scope become methods of the Object class. Since this class is an ancestor of every other class, such methods can be called on any object. They are also visible in all scopes, effectively serving as "global" procedures. Ruby supports
inheritance Inheritance is the practice of passing on private property Private property is a legal designation for the ownership of property by non-governmental legal entities. Private property is distinguishable from public property Public property i ...
with
dynamic dispatch In computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as practical techniques for their application. Computer science is the study of Algo ...
,
mixin In object-oriented programming languages, a mixin (or mix-in) is a class that contains methods for use by other classes without having to be the parent class of those other classes. How those other classes gain access to the mixin's methods depen ...
s and singleton methods (belonging to, and defined for, a single instance rather than being defined on the class). Though Ruby does not support
multiple inheritance Multiple inheritance is a feature of some computer s in which an object or can features from more than one parent object or . It is distinct from single inheritance, where an object or class may only inherit from one particular object or class. ...

multiple inheritance
, classes can import
modules Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a syst ...
as mixins. Ruby has been described as a
multi-paradigm programming language Programming paradigms are a way to classify programming languages based on their features. Languages can be classified into multiple paradigms. Some paradigms are concerned mainly with implications for the execution model of the language, suc ...
: it allows procedural programming (defining functions/variables outside classes makes them part of the root, 'self' Object), with object orientation (everything is an object) or
functional programming In computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as practical techniques for their application. Computer science is the study of , ...
(it has
anonymous function Anonymous may refer to: * Anonymity Anonymity describes situations where the acting person's identity is unknown. Some writers have argued that namelessness, though technically correct, does not capture what is more centrally at stake in context ...
s, closures, and
continuation In computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as practical techniques for their application. Computer science is the study of , , ...
s; statements all have values, and functions return the last evaluation). It has support for
introspection Introspection is the examination of one's own conscious , an English Paracelsian Paracelsianism (also Paracelsism; German: ') was an early modern History of medicine, medical movement based on the theories and therapies of Paracelsus. It de ...
,
reflectionReflection or reflexion may refer to: Philosophy * Self-reflection Science * Reflection (physics), a common wave phenomenon ** Specular reflection, reflection from a smooth surface *** Mirror image, a reflection in a mirror or in water ** Signal r ...
and
metaprogramming Metaprogramming is a programming technique in which computer program In imperative programming In computer science, imperative programming is a programming paradigm that uses Statement (computer science), statements that change a program's sta ...
, as well as support for interpreter-based threads. Ruby features
dynamic typing In programming language A programming language is a formal language comprising a Instruction set architecture, set of instructions that produce various kinds of Input/output, output. Programming languages are used in computer programming to i ...
, and supports
parametric polymorphism In programming language A programming language is a formal language comprising a Instruction set architecture, set of instructions that produce various kinds of Input/output, output. Programming languages are used in computer programming to imp ...
. According to the Ruby FAQ, the syntax is similar to
Perl Perl is a family of two high-level High-level and low-level, as technical terms, are used to classify, describe and point to specific Objective (goal), goals of a systematic operation; and are applied in a wide range of contexts, such as, for ...
's and the semantics are similar to , but the design philosophy differs greatly from Python's.


Features

* Thoroughly
object-oriented Object-oriented programming (OOP) is a programming paradigm Program, programme, programmer, or programming may refer to: Business and management * Program management, the process of managing several related projects * Time management * P ...
with
inheritance Inheritance is the practice of passing on private property Private property is a legal designation for the ownership of property by non-governmental legal entities. Private property is distinguishable from public property Public property i ...
,
mixin In object-oriented programming languages, a mixin (or mix-in) is a class that contains methods for use by other classes without having to be the parent class of those other classes. How those other classes gain access to the mixin's methods depen ...
s and
metaclass In object-oriented programming Object-oriented programming (OOP) is a programming paradigm based on the concept of "Object (computer science), objects", which can contain data and code: data in the form of Field (computer science), fields (oft ...
es *
Dynamic typing In programming language A programming language is a formal language comprising a Instruction set architecture, set of instructions that produce various kinds of Input/output, output. Programming languages are used in computer programming to i ...
and
duck typing Duck typing in computer programming is an application of the duck test The duck test is a form of abductive reasoning Abductive reasoning (also called abduction,For example: abductive inference, or retroduction) is a form of logical inference ...
* Everything is an expression (even
statements Statement or statements may refer to: Common uses *Statement (computer science)In computer programming Computer programming is the process of designing and building an executable computer program to accomplish a specific computing result or to ...
) and everything is executed imperatively (even declarations) * Succinct and flexible syntax that minimizes syntactic noise and serves as a foundation for
domain-specific languagesA domain-specific language (DSL) is a computer languageA computer language is a method of communication with a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. M ...
* Dynamic
reflectionReflection or reflexion may refer to: Philosophy * Self-reflection Science * Reflection (physics), a common wave phenomenon ** Specular reflection, reflection from a smooth surface *** Mirror image, a reflection in a mirror or in water ** Signal r ...
and alteration of objects to facilitate
metaprogramming Metaprogramming is a programming technique in which computer program In imperative programming In computer science, imperative programming is a programming paradigm that uses Statement (computer science), statements that change a program's sta ...
* Lexical closures,
iterator In computer programming, an iterator is an object (computing), object that enables a programmer to traverse a Container (data structure), container, particularly List (abstract data type), lists. Various types of iterators are often provided via a ...
s and generators, with a block syntax * Literal notation for
arrays ARRAY, also known as ARRAY Now, is an independent distribution company launched by film maker and former publicist Ava DuVernay Ava Marie DuVernay (; born August 24, 1972) is an American filmmaker. She won the directing award in the U.S. dram ...

arrays
, hashes, regular expressions and Symbol (Lisp), symbols * Embedding code in strings (Variable interpolation, interpolation) * Default arguments * Four levels of variable scope (Global variable, global, Class variable, class, Instance variable, instance, and Local variable, local) denoted by Sigil (computer programming), sigils or the lack thereof * Garbage collection (computer science), Garbage collection * First-class continuations * Strict boolean Implicit type conversion, coercion rules (everything is ''true'' except false and Null pointer, nil) * Exception handling * Operator overloading * Built-in support for rational numbers, complex numbers and arbitrary-precision arithmetic * Custom dispatch behavior (through method_missing and const_missing) * Native threads and cooperative Fiber (computer science), fibers (fibers are a 1.9/YARV feature) * Support for
Unicode Unicode, formally the Unicode Standard, is an information technology Technical standard, standard for the consistent character encoding, encoding, representation, and handling of Character (computing), text expressed in most of the world's wri ...

Unicode
and multiple
character encoding Character encoding is the process of assigning numbers to graphical Graphics (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country ...
s. * Native Plug-in (computing), plug-in API in C (programming language), C * Interactive Ruby Shell, an interactive command-line interpreter that can be used to test code quickly (Read–eval–print loop, REPL) * Centralized package management through RubyGems * Implemented on all major platforms * Large standard library, including modules for YAML, JSON, XML, Common Gateway Interface, CGI, OpenSSL, HTTP,
FTP The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data c ...

FTP
, RSS, curses (programming library), curses, zlib and Tk * Just-in-time compilation


Syntax

The syntax of Ruby is broadly similar to that of
Perl Perl is a family of two high-level High-level and low-level, as technical terms, are used to classify, describe and point to specific Objective (goal), goals of a systematic operation; and are applied in a wide range of contexts, such as, for ...
and Python (programming language), Python. Class and method definitions are signaled by keywords, whereas code blocks can be defined by either keywords or braces. In contrast to Perl, variables are not obligatorily prefixed with a sigil (computer programming), sigil. When used, the sigil changes the semantics of scope of the variable. For practical purposes there is no distinction between expression (programming), expressions and statement (programming), statements. Line breaks are significant and taken as the end of a statement; a semicolon may be equivalently used. Unlike Python, indentation is not significant. One of the differences from Python and Perl is that Ruby keeps all of its instance variables completely private to the class and only exposes them through accessor methods (attr_writer, attr_reader, etc.). Unlike the "getter" and "setter" methods of other languages like C++ or Java (programming language), Java, accessor methods in Ruby can be created with a single line of code via
metaprogramming Metaprogramming is a programming technique in which computer program In imperative programming In computer science, imperative programming is a programming paradigm that uses Statement (computer science), statements that change a program's sta ...
; however, accessor methods can also be created in the traditional fashion of C++ and Java. As invocation of these methods does not require the use of parentheses, it is trivial to change an instance variable into a full function, without modifying a single line of calling code or having to do any refactoring achieving similar functionality to C Sharp (programming language), C# and VB.NET property members. Python's property descriptors are similar, but come with a trade-off in the development process. If one begins in Python by using a publicly exposed instance variable, and later changes the implementation to use a private instance variable exposed through a property descriptor, code internal to the class may need to be adjusted to use the private variable rather than the public property. Ruby's design forces all instance variables to be private, but also provides a simple way to declare set and get methods. This is in keeping with the idea that in Ruby, one never directly accesses the internal members of a class from outside the class; rather, one passes a message to the class and receives a response.


Implementations


Matz's Ruby interpreter

The original Ruby interpreter (computer software), interpreter is often referred to as Ruby MRI, Matz's Ruby Interpreter or MRI. This implementation is written in C and uses its own Ruby-specific virtual machine. The standardized and retired Ruby 1.8 Ruby MRI, implementation was written in C (programming language), C, as a single-pass interpreted language. Starting with Ruby 1.9, and continuing with Ruby 2.x and above, the official Ruby interpreter has been YARV ("Yet Another Ruby VM"), and this implementation has superseded the slower virtual machine used in previous releases of MRI.


Alternate implementations

, there are a number of alternative implementations of Ruby, including JRuby, Rubinius, and mruby. Each takes a different approach, with JRuby and Rubinius providing
just-in-time compilation In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softwar ...
and mruby also providing ahead-of-time compilation. Ruby has three major alternate implementations: * JRuby, a mixed Java (programming language), Java and Ruby implementation that runs on the Java virtual machine. JRuby currently targets Ruby 2.5. * TruffleRuby, a Java implementation using the Truffle language implementation framework with GraalVM * Rubinius, a C++ bytecode virtual machine that uses LLVM to compile to machine code at runtime. The bytecode compiler and most core classes are written in pure Ruby. Rubinius currently targets Ruby 2.3.1. Other Ruby implementations include: * MagLev (software), MagLev, a
Smalltalk Smalltalk is an , . Smalltalk was created as the language underpinning the "new world" of computing exemplified by "human–computer symbiosis". It was designed and created in part for al use, specifically for , at the Learning Research Group ...

Smalltalk
implementation that runs on GemTalk Systems' Gemstone (database), GemStone/S VM * mruby, an implementation designed to be embedded into C code, in a similar vein to Lua (programming language), Lua. It is currently being developed by Yukihiro Matsumoto and others * RGSS, or Ruby Game Scripting System, a Proprietary software, proprietary implementation that is used by the RPG Maker series of software for game design and modification of the RPG Maker engine * julializer, a transpiler (partial) from Ruby to Julia (programming language), Julia. It can be used for a large speedup over e.g. Ruby or JRuby implementations (may only be useful for numerical code). * Topaz (Ruby), Topaz, a Ruby implementation written in Python (programming language), Python * Opal (Ruby), Opal, a web-based interpreter that compiles Ruby to JavaScript Other now defunct Ruby implementations were: * MacRuby, a macOS, Mac OS X implementation on the Objective-C runtime. Its iOS counterpart is called RubyMotion * IronRuby an implementation on the .NET Framework * Cardinal, an implementation for the Parrot virtual machine * Ruby Enterprise Edition, often shortened to ''ree'', an implementation optimized to handle large-scale
Ruby on Rails Ruby on Rails, or Rails, is a server-side In the client–server model Client-server model is a distributed application Distributed computing is a field of computer science Computer science deals with the theoretical foundations of ...
projects * HotRuby, a JavaScript and ActionScript implementation of the Ruby programming language The maturity of Ruby implementations tends to be measured by their ability to run the
Ruby on Rails Ruby on Rails, or Rails, is a server-side In the client–server model Client-server model is a distributed application Distributed computing is a field of computer science Computer science deals with the theoretical foundations of ...
(Rails) framework, because it is complex to implement and uses many Ruby-specific features. The point when a particular implementation achieves this goal is called "the Rails singularity". The reference implementation, JRuby, and Rubinius are all able to run Rails unmodified in a production environment.


Platform support

Matsumoto originally developed Ruby on the BSD, 4.3BSD-based Sony NEWS, Sony NEWS-OS 3.x, but later migrated his work to SunOS 4.x, and finally to Linux. By 1999, Ruby was known to work across many different operating systems, including NEWS-OS, SunOS, AIX, SVR4, Solaris (operating system), Solaris, NEC UP-UX, NeXTSTEP, BSD, Linux, Classic Mac OS, Mac OS, DOS, Windows (operating system), Windows, and BeOS. Modern Ruby versions and implementations are available on many operating systems, such as Linux, BSD, Solaris, AIX, macOS, Windows, Windows Phone, Windows CE, Symbian OS, BeOS, OpenVMS, and IBM i. Ruby programming language is supported across a number of cloud hosting platforms like Jelastic, Heroku, Google Cloud Platform and others.


Repositories and libraries

RubyGems is Ruby's package manager. A Ruby package is called a "gem" and can be installed via the command line. Most gems are libraries, though a few exist that are applications, such as integrated development environment, IDEs. There are over 100,000 Ruby gems hosted o
RubyGems.org
Many new and existing Ruby libraries are hosted on GitHub, a service that offers Revision control, version control repository hosting for Git (software), Git. The Ruby Application Archive, which hosted applications, documentation, and libraries for Ruby programming, was maintained until 2013, when its function was transferred to RubyGems.


See also

* Comparison of programming languages * Metasploit Project * Why's (poignant) Guide to Ruby * XRuby * Crystal (programming language)


References


Further reading

* * * * * * * * * *


External links

*
Ruby documentation
* {{Authority control Ruby (programming language), Articles with example Ruby code Class-based programming languages Dynamic programming languages Dynamically typed programming languages Free software programmed in C ISO standards Japanese inventions Multi-paradigm programming languages Object-oriented programming languages Programming languages created in 1995 Programming languages with an ISO standard Scripting languages Software using the BSD license Text-oriented programming languages Free compilers and interpreters