View source for Ruby (programming language)

{{Short description|General-purpose programming language}}
{{Distinguish|Ruby on Rails|Ruby (hardware description language)}}
{{infobox programming language
| logo = Ruby logo.svg
| paradigm = [[Multi-paradigm programming language|Multi-paradigm]]: [[functional programming|functional]], [[imperative programming|imperative]], [[object-oriented programming|object-oriented]], [[reflective programming|reflective]]
| designer = [[Yukihiro Matsumoto]]
| developer = Yukihiro Matsumoto, et al.
| latest_release_version = {{wikidata|property|edit|Q161053|P348}}<ref name="Ruby 3.3.0 Released" />
| latest_release_date = {{start date and age|{{wikidata|qualifier|Q161053|P348|P577}}}}
| typing = [[Duck typing|Duck]], [[Dynamic typing|dynamic]], [[Strong typing|strong]]
| scope = Lexical, sometimes dynamic
| implementations = [[Ruby MRI]], [[GraalVM#Language and Runtime Support|TruffleRuby]], [[YARV]], [[Rubinius]], [[JRuby]], [[RubyMotion]], [[mruby]]
| influenced = [[Clojure]], [[CoffeeScript]], [[Crystal (programming language)|Crystal]], [[D (programming language)|D]], [[Elixir (programming language)|Elixir]], [[Groovy (programming language)|Groovy]], [[Julia (programming language)|Julia]],<ref name="Julia" /> [[Mirah (programming language)|Mirah]], [[Nu (programming language)|Nu]],<ref name="Burks" /> [[Ring (programming language)|Ring]],<ref name="Ring and other languages" /> [[Rust (programming language)|Rust]],<ref name="rust"/> [[Swift (programming language)|Swift]]<ref name="lattner2014" />
| license = [[Ruby License]]
| website = {{URL|https://www.ruby-lang.org/en/|ruby-lang.org}}
| wikibooks = Ruby Programming
| year = {{start date and age|1995}}
| programming_language = [[C (programming language)|C]]
| influenced_by = [[Ada (programming language)|Ada]],<ref name="nov2pro"/> [[BASIC|Basic]],<ref name="confreaks" /> [[C++]],<ref name="nov2pro"/> [[CLU (programming language)|CLU]],<ref name="bini"/> [[Dylan (programming language)|Dylan]],<ref name="bini" /><br />[[Eiffel (programming language)|Eiffel]],<ref name="nov2pro" /> [[Lisp (programming language)|Lisp]],<ref name="bini"/> [[Lua (programming language)|Lua]], [[Perl]],<ref name="bini" /> [[Python (programming language)|Python]],<ref name="bini"/> [[Smalltalk]]<ref name="bini" />
| operating_system = [[Cross-platform]]
| file_ext = .rb, .ru
}}

'''Ruby''' is a [[general-purpose programming language]]. It was designed with an emphasis on programming productivity and simplicity. In Ruby, everything is an [[object (computer science)|object]], including [[primitive data type]]s. It was developed in the mid-1990s by [[Yukihiro Matsumoto|Yukihiro "Matz" Matsumoto]] in [[Japan]].

Ruby is [[interpreted language|interpreted]], [[high-level programming language|high-level]], and [[Dynamic typing|dynamically typed]]; its interpreter uses [[garbage collection (computer science)|garbage collection]] and [[just-in-time compilation]]. It supports multiple programming paradigms, including [[procedural programming|procedural]], [[object-oriented programming|object-oriented]], and [[functional programming]]. According to the creator, Ruby was influenced by [[Perl]], [[Smalltalk]], [[Eiffel (programming language)|Eiffel]], [[Ada (programming language)|Ada]], [[BASIC]], and [[Lisp (programming language)|Lisp]].<ref name="about"/><ref name="confreaks" />

== History ==
=== Early concept ===
According to Matsumoto, Ruby was conceived in 1993. In a 1999 post to the Ruby-Talk mailing list, he shared some of his early ideas about the language:<ref>{{cite web|url=https://www.ruby-lang.org/en/documentation/faq/|title=Official Ruby FAQ|author=Shugo Maeda|date=17 December 2002}}</ref>

{{Blockquote|I was talking with my colleague about the possibility of an object-oriented scripting language. I knew Perl (Perl4, not Perl5), but I didn't like it really, because it had the smell of a [[toy language]] (it still has). The object-oriented language seemed very promising. I knew [[Python (programming language)|Python]] then. But I didn't like it, because I didn't think it was a true object-oriented language{{snd}} OO features appeared to be add-on to the language. As a language maniac and OO fan for 15 years, I really wanted a genuine object-oriented, easy-to-use scripting language. I looked for but couldn't find one. So I decided to make it.}}

Matsumoto described Ruby's design as resembling a simple [[Lisp (programming language)|Lisp]] language at its core, with an object system like that of Smalltalk, blocks inspired by [[higher-order function]]s, and practical utility like that of Perl.<ref name="lisp-features"/>

The name "Ruby" originated during an online chat session between Matsumoto and Keiju Ishitsuka on 24 February 1993, before any code had been written.<ref name="rubyconf-history-of-ruby"/> Two names were initially proposed: "Coral" and "Ruby". Matsumoto chose the latter in a subsequent email to Ishitsuka.<ref name="ruby-name"/> He also noted that one factor influencing the choice of the name was that a colleague's [[birthstone]] was [[Ruby_(gemstone)|ruby]].<ref name="faq-name"/><ref name="ruby-talk-name"/>

=== Early releases ===

The first public release of Ruby 0.95 was announced on Japanese domestic [[newsgroup]]s on 21 December 1995.<ref name="0.95"/><ref name="ruby-history"/> Subsequently, three more versions of Ruby were released in two days.<ref name="rubyconf-history-of-ruby"/> The release coincided with the launch of the [[Japanese language|Japanese-language]] ''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 programming|object-oriented]] design, [[Class (programming)|classes]] with inheritance, [[mixin]]s, [[iterator]]s, [[Closure (computer science)|closures]], [[exception handling]] and [[Garbage collection (computer science)|garbage collection]].<ref name="tutorial-features"/>

After the release of Ruby 0.95 in 1995, several stable versions of Ruby were released in these years.<ref name="rubyconf-history-of-ruby"/>

In 1997, the first article about Ruby was published on the Web. In the same year, Matsumoto was hired by [[Network Applied Communication Laboratory|netlab.jp]] to work on Ruby as a full-time developer.<ref name="rubyconf-history-of-ruby"/>

In 1998, the Ruby Application Archive was launched by Matsumoto, along with a simple English-language homepage for Ruby.<ref name="rubyconf-history-of-ruby"/>

In 1999, the first English language mailing list ''ruby-talk'' began, which signaled a growing interest in the language outside Japan.<ref name="linuxdevcenter"/> 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 in October 1999. It would be followed in the early 2000s by around 20 books on Ruby published in Japanese.<ref name="rubyconf-history-of-ruby"/>

By 2000, Ruby was more popular than Python in Japan.<ref name="programming-ruby"/> In September 2000, the first English language book ''[[Programming Ruby]]'' 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.<ref name="1.8.7-retirement"/> Although deprecated, there is still code based on it. Ruby 1.8 is only partially compatible with Ruby 1.9.{{cn|date=April 2025}}

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 [[Government of Japan|Japanese government]] agency) for submission to the [[Japanese Industrial Standards Committee]] (JISC) and then to the [[International Organization for Standardization]] (ISO). It was accepted as a Japanese Industrial Standard (JIS X 3017) in 2011<ref name="JIS X 3017"/> and an international standard (ISO/IEC 30170) in 2012.<ref name="IPA"/><ref name="IEC 30170"/>
[[File:Ruby On Rails Logo.svg|thumb|[[Ruby on Rails]] logo]]
Around 2005, interest in the Ruby language surged in tandem with [[Ruby on Rails]], a [[web framework]] written in Ruby. Rails is frequently credited with increasing awareness of Ruby.<ref name="Devarticles"/>

Effective with Ruby 1.9.3, released 31 October 2011,<ref name="Ruby 1.9.3"/> 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.<ref name="license-change"/> Adoption of 1.9 was slowed by changes from 1.8 that required many popular third party [[#Repositories and libraries|gems]] to be rewritten.{{cn|date=April 2025}}

=== 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 24 February 2013, there were only five known incompatibilities.<ref name="2-0-release-incompatibilities"/>

Starting with 2.1.0, Ruby's versioning policy changed to be more similar to [[semantic versioning]], although it differs slightly in that minor version increments may be API incompatible.<ref name="semantic-versioning"/>

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{{snd}}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]] 7.0 specification. Since version 2.2.1,<ref name="2-2-1-release"/> [[Ruby (programming language)#Matz's Ruby interpreter|Ruby MRI]] performance on [[ppc64|PowerPC64]] was improved.<ref name="2-2-1-changelog"/><ref name="Pedrosa-1"/><ref name="Pedrosa-2"/> 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.<ref name="obsolete-or-gone-in-2.2"/>

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.<ref name="Ruby 2.3.0 NEWS"/> Other notable changes include:

* The ability to mark all [[string literal]]s as frozen by default with a consequently large performance increase in string operations.<ref name="frozen-strings"/>
* Hash comparison to allow direct checking of key/value pairs instead of just keys.
* A new [[safe navigation operator]] <code>&.</code> that can ease nil handling (e.g. instead of {{code|lang=ruby|code=if obj && obj.foo && obj.foo.bar}}, we can use <code>if obj&.foo&.bar</code>).
* 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 <syntaxhighlight inline lang=ruby>profile = { social: { wikipedia: { name: 'Foo Baz' } } }</syntaxhighlight>, the value ''Foo Baz'' can now be retrieved by <code>profile.dig(:social, :wikipedia, :name)</code>).
* <code>.grep_v(regexp)</code> 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.<ref name=":0"/> 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.<ref name="Ruby 3.0.0 Released"/> It is known as Ruby 3x3, which signifies that programs would run three times faster in Ruby 3.0 comparing to Ruby 2.0.<ref>{{cite web |last=Scheffler |first=Jonan |date=10 November 2016 |title=Ruby 3x3: Matz, Koichi, and Tenderlove on the future of Ruby Performance |url=https://blog.heroku.com/ruby-3-by-3 |access-date=18 May 2019 |website=Ruby |language=en-US |archive-date=10 May 2019 |archive-url=https://web.archive.org/web/20190510225935/https://blog.heroku.com/ruby-3-by-3 |url-status=live }}</ref> and some had already implemented in intermediate releases on the road from 2 to 3. To achieve 3x3, Ruby 3 comes with MJIT, and later YJIT, Just-In-Time Compilers, to make programs faster, although they are described as experimental and remain disabled by default (enabled by flags at runtime).

Another goal of Ruby 3.0 is to improve [[Concurrency (computer science)|concurrency]] and two more utilities Fibre Scheduler, and experimental Ractor facilitate the goal.<ref name="Ruby 3.0.0 Released"/> 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 program analysis|static analysis]].<ref name="Ruby 3.0.0 Released"/> It is separated from general Ruby programs.

There are some syntax enhancements and library changes in Ruby 3.0 as well.<ref name="Ruby 3.0.0 Released"/>

Ruby 3.1 was released on 25 December 2021.<ref name="Ruby 3.1.0 Released" /> It includes YJIT, a new, experimental, Just-In-Time Compiler developed by [[Shopify]], to enhance the performance of real world business applications. A new [[debugger]] is also included. There are some syntax enhancements and other improvements in this release. Network libraries for [[FTP]], [[SMTP]], [[IMAP]], and [[Post Office Protocol|POP]] are moved from default gems to bundled gems.<ref>{{cite web|url=https://www.ruby-lang.org/en/news/2021/12/25/ruby-3-1-0-released//|title=Ruby 3.1.0 Released|access-date=2021-12-26|archive-date=2021-12-26|archive-url=https://web.archive.org/web/20211226065055/https://www.ruby-lang.org/en/news/2021/12/25/ruby-3-1-0-released//|url-status=live}}</ref>

Ruby 3.2 was released on 25 December 2022.<ref name="Ruby 3.2.0 Released">{{Cite web|url=https://www.ruby-lang.org/en/news/2022/12/25/ruby-3-2-0-released/|title=Ruby 3.2.0 Released|access-date=2022-12-25|archive-date=2022-12-25|archive-url=https://web.archive.org/web/20221225084459/https://www.ruby-lang.org/en/news/2022/12/25/ruby-3-2-0-released/|url-status=live}}</ref> It brings support for being run inside of a [[WebAssembly]] environment via a WASI interface. [[Regular expression]]s also receives some improvements, including a faster, [[memoization|memoized]] matching algorithm to protect against certain [[ReDoS]] attacks, and configurable timeouts for regular expression matching. Additional debugging and syntax features are also included in this release, which include syntax suggestion, as well as error highlighting. The MJIT compiler has been re-implemented as a standard library module, while the YJIT, a [[Rust (programming language)|Rust]]-based [[Just-in-time compilation|JIT]] compiler now supports more architectures on Linux.

Ruby 3.3 was released on 25 December 2023.<ref name="Ruby 3.3.0 Released">{{Cite web|url=https://www.ruby-lang.org/en/news/2023/12/25/ruby-3-3-0-released/|title=Ruby 3.3.0 Released|access-date=2023-12-25|archive-date=2023-12-25|archive-url=https://web.archive.org/web/20231225071449/https://www.ruby-lang.org/en/news/2023/12/25/ruby-3-3-0-released/|url-status=live}}</ref> Ruby 3.3 introduces significant enhancements and performance improvements to the language. Key features include the introduction of the Prism parser for portable and maintainable parsing, the addition of the pure-Ruby JIT compiler RJIT, and major performance boosts in the YJIT compiler. Additionally, improvements in memory usage, the introduction of an M:N thread scheduler, and updates to the standard library contribute to a more efficient and developer-friendly Ruby ecosystem.

Ruby 3.4 was released on 25 December 2024.<ref name="Ruby 3.4.0 Released">{{cite web|url=https://www.ruby-lang.org/en/news/2024/12/25/ruby-3-4-0-released/ |title=Ruby 3.4.0 Released |date=2024-12-25 |access-date=2025-04-12}}</ref> Ruby 3.4 adds <code>it</code> block parameter reference, changes Prism as default parser, adds [[Happy Eyeballs]] Version 2 support to socket library, improves YJIT, adds modular Garbage Collector and so on.<ref>{{cite web |url=https://docs.ruby-lang.org/en/3.4/NEWS_md.html |title=NEWS - Documentation for Ruby 3.4 |access-date=2025-04-12}}</ref>

== Semantics and philosophy ==
[[File:Yukihiro Matsumoto.JPG|thumb|[[Yukihiro Matsumoto]], the creator of Ruby]]

Matsumoto stated that Ruby is designed for programmer productivity and fun, following the principles of good [[user interface]] design.<ref name="informit" /> At a Google Tech Talk in 2008 he said, "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."<ref name="googletechtalk" /> He stresses that systems design needs to emphasize human, rather than computer, needs:<ref name="artima" />

{{blockquote|
Often people, especially computer engineers, focus on the machines. They think, "By doing this, the machine will run fast. By doing this, the machine will run more effectively. By doing this, the machine will something something something." They are focusing on machines. But in fact we need to focus on humans, on how humans care about doing programming or operating the application of the machines. We are the masters. They are the slaves.
}}

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]] (POLA) to the design of Ruby;<ref name="artima" /> 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.<ref name="rubyweeklynews" />

Matsumoto defined it this way in an interview:<ref name="artima" />

{{blockquote|
Everyone has an individual background. Someone may come from Python, someone else may come from Perl, and they may be surprised by different aspects of the language. Then they come up to me and say, 'I was surprised by this feature of the language, so Ruby violates the principle of least surprise.' Wait. Wait. The principle of least surprise is not for you only. The principle of least surprise means principle of least ''my'' surprise. And it means the principle of least surprise after you learn Ruby very well. For example, I was a C++ programmer before I started designing Ruby. I programmed in C++ exclusively for two or three years. And after two years of C++ programming, it still surprises me.
}}

Ruby is [[Object-oriented programming|object-oriented]]: every value is an object, including classes and instances of types that many other languages designate as primitives (such as [[Integer (computer science)|integers]], Booleans, and "[[null pointer|null]]"). Because everything in Ruby is an object, everything in Ruby has certain built-in abilities called methods. Every [[function (programming)|function]] is a [[Method (computer programming)|method]] 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 (object-oriented programming)|inheritance]] with [[dynamic dispatch]], [[mixin]]s and singleton methods (belonging to, and defined for, a single [[instance (computer science)|instance]] rather than being defined on the class). Though Ruby does not support [[multiple inheritance]], classes can import [[Modular programming|modules]] as mixins.

Ruby has been described as a [[multi-paradigm programming language]]: 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]] (it has [[anonymous function]]s, [[Closure (computer science)|closures]], and [[continuation]]s; statements all have values, and functions return the last evaluation). It has support for [[Introspection (computer science)|introspection]], [[reflective programming]], [[metaprogramming]], and interpreter-based [[Thread (computer science)|threads]]. Ruby features [[Type system|dynamic typing]], and supports [[parametric polymorphism]].

According to the Ruby FAQ, the syntax is similar to [[Perl]]'s and the semantics are similar to [[Smalltalk|Smalltalk's]], but the design philosophy differs greatly from [[Python (programming language)|Python]]'s.<ref name="faq-comparison" />

== Features ==

* Thoroughly [[Object-oriented programming|object-oriented]] with [[Inheritance (object-oriented programming)|inheritance]], [[mixin]]s and [[metaclass]]es<ref name="stewart" />
* [[Dynamic typing]] and [[duck typing]]
* Everything is an [[Expression (programming)|expression]] (even [[Statement (programming)|statements]]) and everything is executed [[Imperative programming|imperatively]] (even [[Declaration (computer science)|declarations]])
* Succinct and flexible syntax<ref name="venners-productivity" /> that minimizes [[syntactic noise]] and serves as a foundation for [[domain-specific languages]]<ref name="fowler-dsl" />
* Dynamic [[Reflective programming|reflection]] and [[Dynamic programming language#Object runtime alteration|alteration]] of objects to facilitate [[metaprogramming]]<ref name="codeproject-dynamic" />
* [[Closure (computer science)|Lexical closures]], [[iterator]]s and [[Generator (computer science)|generators]], with a [[Ruby syntax#Blocks and iterators|block syntax]]<ref name="venners-closures" />
* Literal notation for [[Dynamic array|arrays]], [[Associative array|hashes]], [[regular expression]]s and [[Symbol (Lisp)|symbols]]
* Embedding code in strings ([[Variable interpolation|interpolation]])
* [[Default argument]]s
* 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 continuation]]s
* Strict Boolean [[Implicit type conversion|coercion]] rules (everything is ''true'' except <code>false</code> and <code>[[Null pointer|nil]]</code>)
* [[Exception handling]]
* [[Operator overloading]]<ref name="Methods"/>
* Built-in support for [[rational number]]s, [[complex number]]s and [[arbitrary-precision arithmetic]]
* Custom dispatch behavior (through <code>method_missing</code> and <code>const_missing</code>)
* Native [[Thread (computer science)|threads]] and cooperative [[Fiber (computer science)|fibers]] (fibers are a 1.9/[[YARV]] feature)
* Support for [[Unicode]] and multiple [[character encoding]]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]], [[RSS]], [[curses (programming library)|curses]], [[zlib]] and [[Tk (software)|Tk]]<ref name="stdlib-master" />
* [[Just-in-time compilation]]

== Syntax ==
{{main|Ruby syntax}}

The syntax of Ruby is broadly similar to that of [[Perl]] 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]].<ref name="while"/><ref name="precedence"/> 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 (<code>attr_writer</code>, <code>attr_reader</code>, 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]]; 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 <code>set</code> and <code>get</code> 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 ==
{{See also|Ruby MRI#Operating systems|List of Ruby compilers}}

=== 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]].<ref name="1.8.7-retirement"/>

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.

=== Alternative implementations ===


{{As of|2018}}, 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]] and mruby also providing [[ahead-of-time compilation]].

Ruby has three major alternative implementations:

* [[JRuby]], a mixed [[Java (programming language)|Java]] and Ruby implementation that runs on the [[Java virtual machine]]. JRuby currently targets Ruby 3.1.x.
* 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{{when|date=April 2025}} targets Ruby 2.3.1.

Other Ruby implementations include:

* [[MagLev (software)|MagLev]], a [[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 used by the [[RPG Maker]] series of [[role-playing game creation software]] for game design and modification of the RPG Maker [[game 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).<ref name="virtual-module"/>
* Topaz, a Ruby implementation written in [[Python (programming language)|Python]]
* 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]] 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]] (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<ref name="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]].<ref name="Stodte"/><ref name="initial-development"/> By 1999, Ruby was known to work across many different [[operating system]]s. Modern Ruby versions and implementations are available on all major desktop, mobile and server-based operating systems. Ruby is also supported across a number of cloud hosting platforms like [[Jelastic]], [[Heroku]], [[Google Cloud Platform]] and others.

Tools such as [[Ruby Version Manager|RVM]] and RBEnv, facilitate installation and partitioning of multiple ruby versions, and multiple 'gemsets' on one machine.

== 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]].<ref name="ruby-toolbox"/> There are over 100,000 Ruby gems hosted on [https://rubygems.org/ RubyGems.org].<ref>{{cite web|url=https://rubygems.org/stats|title=Stats RubyGems.org your community gem host|website=rubygems.org|access-date=10 December 2021|archive-date=10 December 2021|archive-url=https://web.archive.org/web/20211210161811/https://rubygems.org/stats|url-status=live}}</ref>

Many new and existing Ruby libraries are hosted on [[GitHub]], a service that offers [[Revision control|version control]] repository hosting for [[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.<ref name="raa-retirement"/>

== See also ==
{{Portal|Free and open-source software|Computer programming}}

* [[Comparison of programming languages]]
* [[List of computer books#Ruby|List of Ruby programming books]]
* [[List of Ruby software and tools]]
* [[Metasploit]]
* [[Why's (poignant) Guide to Ruby]]
* [[Crystal (programming language)]]
* [[Ruby on Rails]]

==External links==
* [https://www.ruby-lang.org/en/documentation/ Ruby documentation]

== References ==

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<ref name="Ring and other languages">{{cite web | url = https://ring-lang.sourceforge.net/doc1.6/introduction.html#ring-and-other-languages | title = Ring and other languages | author = Ring Team | date = 3 December 2017 | work = ring-lang.net | publisher = ring-lang | access-date = 3 December 2017 | archive-date = 25 December 2018 | archive-url = https://web.archive.org/web/20181225175312/http://ring-lang.sourceforge.net/doc1.6/introduction.html#ring-and-other-languages | url-status = live }}</ref>
<ref name="rust">{{Cite web |url=https://doc.rust-lang.org/reference/influences.html |title=Influences - The Rust Reference |website=The Rust Reference |access-date=2023-04-18 |archive-date=2019-01-26 |archive-url=https://web.archive.org/web/20190126051127/https://doc.rust-lang.org/reference/influences.html |url-status=live }}</ref>
<ref name="lattner2014">{{cite web | url = http://nondot.org/sabre/ | title = Chris Lattner's Homepage | last = Lattner | first = Chris | date = 2014-06-03 | access-date = 2014-06-03 | publisher = Chris Lattner | quote = The Swift language is the product of tireless effort from a team of language experts, documentation gurus, compiler optimization ninjas, and an incredibly important internal dogfooding group who provided feedback to help refine and battle-test ideas. Of course, it also greatly benefited from the experiences hard-won by many other languages in the field, drawing ideas from Objective-C, Rust, Haskell, Ruby, Python, C#, CLU, and far too many others to list. | archive-date = 2018-12-25 | archive-url = https://web.archive.org/web/20181225175312/http://nondot.org/sabre/ | url-status = live }}</ref>
<ref name="nov2pro">{{ cite book | last = Cooper | first = Peter | title = Beginning Ruby: From Novice to Professional | edition = 2nd | series = Beginning from Novice to Professional | year = 2009 | publisher = APress | location = Berkeley | isbn = 978-1-4302-2363-4 | page = 101 | quote = To a lesser extent, Python, LISP, Eiffel, Ada, and C++ have also influenced Ruby.}}</ref>
<ref name="confreaks">{{cite web | url = https://www.youtube.com/watch?v=vDnOBXD167k | title = Reasons behind Ruby | work = Ruby Conference 2008 | date = 15 April 2013 | publisher = Confreaks (YouTube) }}</ref>
<ref name="bini">{{ cite book | last = Bini | first = Ola | title = Practical JRuby on Rails Web 2.0 Projects: Bringing Ruby on Rails to Java | year = 2007 | publisher = APress | location = Berkeley | isbn = 978-1-59059-881-8 | page = [https://archive.org/details/practicaljrubyon0000bini/page/3 3] | quote = It draws primarily on features from Perl, Smalltalk, Python, Lisp, Dylan, and CLU. | url = https://archive.org/details/practicaljrubyon0000bini/page/3}}</ref>
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<!-- <ref name="FAQ">{{cite web|url=https://www.ruby-lang.org/en/documentation/faq/|title=Official Ruby FAQ}}</ref> -->
<ref name="lisp-features">{{ cite web | url = http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/179642 | title = Re: Ruby's lisp features. | last = Matsumoto | first = Yukihiro | author-link = Yukihiro Matsumoto | date = 13 February 2006 | access-date = 15 February 2020 | url-status = dead | archive-url = https://web.archive.org/web/20181027195101/http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/179642 | archive-date = 2018-10-27}}</ref>
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<ref name="ruby-talk-name">{{cite mailing list | url = http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/394 | title = Re: the name of Ruby? | mailing-list = Ruby-Talk | date = June 11, 1999 | author = [[Yukihiro Matsumoto]] | access-date = April 10, 2012 | archive-date = December 25, 2018 | archive-url = https://web.archive.org/web/20181225131629/http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/394%0A%20 | url-status = dead }}</ref>
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<ref name="JIS X 3017">{{cite web|url=http://www.ipa.go.jp/about/press/20110322.html|title=IPA 独立行政法人 情報処理推進機構：プレス発表 プログラム言語RubyのJIS規格（JIS X 3017）制定について|access-date=2 May 2015|archive-date=2 February 2015|archive-url=https://web.archive.org/web/20150202010444/http://www.ipa.go.jp/about/press/20110322.html|url-status=dead}}</ref>
<ref name="IPA">{{cite web|url=http://www.ipa.go.jp/about/press/20120402_2.html|title=IPA 独立行政法人 情報処理推進機構：プレス発表 プログラム言語Ruby、国際規格として承認|access-date=2 May 2015|archive-date=1 February 2015|archive-url=https://web.archive.org/web/20150201213420/http://www.ipa.go.jp/about/press/20120402_2.html|url-status=dead}}</ref>
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<ref name="Ruby 1.9.3">{{cite web | title = Ruby 1.9.3 p0 is released | url = https://www.ruby-lang.org/en/news/2011/10/31/ruby-1-9-3-p0-is-released/ | publisher = ruby-lang.org | date = October 31, 2011 | access-date = February 20, 2013 | archive-date = January 14, 2013 | archive-url = https://web.archive.org/web/20130114080108/http://www.ruby-lang.org/en/news/2011/10/31/ruby-1-9-3-p0-is-released/ | url-status = live }}</ref>
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<ref name="2-0-release-incompatibilities">Endoh, Yusuke. (2013-02-24) [http://www.ruby-lang.org/en/news/2013/02/24/ruby-2-0-0-p0-is-released/#label-8 Ruby 2.0.0-p0 is released] {{Webarchive|url=https://web.archive.org/web/20130227014031/http://www.ruby-lang.org/en/news/2013/02/24/ruby-2-0-0-p0-is-released/#label-8 |date=2013-02-27 }}. Ruby-lang.org. Retrieved on 2013-07-17.</ref>
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<ref name="initial-development">{{cite web|url=http://osdir.com/ml/lang-ruby-general/2002-08/msg02494.html|title=lang-ruby-general: Re: question about Ruby initial development|author=Yukihiro Matsumoto|date=August 2002|access-date=3 March 2014|archive-date=3 March 2014|archive-url=https://web.archive.org/web/20140303174016/http://osdir.com/ml/lang-ruby-general/2002-08/msg02494.html|url-status=live}}</ref>

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<ref name="errors">{{ cite web|url=http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/170|title=ruby-talk: Re: hah, check these errors|author=Yukihiro Matsumoto|date=5 January 1999|access-date=3 March 2014}}</ref>
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<ref name=windows-phone>{{ cite web|url=http://msdn.microsoft.com/en-us/magazine/ff960707.aspx|title=Iron Ruby on Windows Phone 7}}</ref>
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<ref name="ruby-toolbox">{{cite web |url=https://www.ruby-toolbox.com/ |title=The Ruby Toolbox |access-date=2015-04-04 |archive-date=2015-04-03 |archive-url=https://web.archive.org/web/20150403032259/https://www.ruby-toolbox.com/ |url-status=live }}</ref>
<ref name="raa-retirement">{{cite web|url=https://www.ruby-lang.org/en/news/2013/08/08/rip-raa/|title=We retire raa.ruby-lang.org|date=2013-08-08|access-date=2016-01-03|archive-date=2015-12-31|archive-url=https://web.archive.org/web/20151231151747/http://www.ruby-lang.org/en/news/2013/08/08/rip-raa/|url-status=live}}</ref>
</references>

== Further reading ==

{{refbegin}}
* {{ citation | first1 = David | last1 = Black | first2 = Joseph | last2 = Leo | date = 15 March 2019 | title = The Well-Grounded Rubyist | edition = Third | publisher = [[Manning Publications]] | page = 584 | isbn = 978-1617295218 }}
* {{citation | first1 = Sandi | last1 = Metz | date = 22 August 2018 | title = Practical Object-Oriented Design: An Agile Primer Using Ruby | edition = Second | publisher = [[Addison-Wesley Professional]] | page = 288 | isbn = 978-0-13-445647-8 | url = https://www.informit.com/store/practical-object-oriented-design-an-agile-primer-using-9780134456478 | access-date = 13 February 2020 | archive-date = February 13, 2020 | archive-url = https://web.archive.org/web/20200213161150/https://www.informit.com/store/practical-object-oriented-design-an-agile-primer-using-9780134456478 | url-status = live }}
* {{ citation | first1 = Peter | last1 = Cooper | date = 12 July 2016 | title = Beginning Ruby: From Novice to Professional | edition = Third | publisher = [[Apress]] | page = 492 | isbn = 978-1484212790 }}
* {{citation | first1 = Lucas | last1 = Carlson | first2 = Leonard | last2 = Richardson | date = 3 April 2015 | title = Ruby Cookbook: Recipes for Object-Oriented Scripting | edition = Second | publisher = [[O'Reilly Media]] | page = 963 | isbn = 978-1449373719 | url = http://oreilly.com/catalog/9781449373719 }}
* {{citation | first1 = Hal | last1 = Fulton | first2 = André | last2 = Arko | date = 2 March 2015 | title = The Ruby Way: Solutions and Techniques in Ruby Programming | edition = Third | publisher = [[Addison-Wesley Professional]] | page = 816 | isbn = 978-0-321-71463-3 | url = https://www.informit.com/store/ruby-way-solutions-and-techniques-in-ruby-programming-9780321714633 | access-date = 13 February 2020 | archive-date = February 13, 2020 | archive-url = https://web.archive.org/web/20200213161150/https://www.informit.com/store/ruby-way-solutions-and-techniques-in-ruby-programming-9780321714633 | url-status = live }}
* {{ citation | first1 = Dave | last1 = Thomas | first2 = Chad | last2 = Fowler | first3 = Andy | last3 = Hunt | date = 7 July 2013 | title = Programming Ruby 1.9 & 2.0: The Pragmatic Programmers' Guide | edition = Fourth | publisher = [[Pragmatic Bookshelf]] | page = 888 | isbn = 978-1937785499 }}
* {{ citation | first1 = Jeremy | last1 = McAnally | first2 = Assaf | last2 = Arkin | date = 28 March 2009 | title = Ruby in Practice | edition = First | publisher = [[Manning Publications]] | page = 360 | isbn = 978-1933988474 }}
* {{citation | first1 = David | last1 = Flanagan | first2 = Yukihiro | last2 = Matsumoto | date = 25 January 2008 | title = The Ruby Programming Language | edition = First | publisher = [[O'Reilly Media]] | page = [https://archive.org/details/rubyprogrammingl00davi/page/446 446] | isbn = 978-0-596-51617-8 | url = https://archive.org/details/rubyprogrammingl00davi/page/446 }}
* {{citation | first1 = Kevin | last1 = Baird | date = June 8, 2007 | title = Ruby by Example: Concepts and Code | edition = First | publisher = [[No Starch Press]] | page = 326 | isbn = 978-1593271480 | url = https://nostarch.com/rubyex | access-date = 13 February 2020 | archive-date = January 13, 2020 | archive-url = https://web.archive.org/web/20200113062530/https://nostarch.com/rubyex | url-status = live }}
* {{citation | first1 = Michael | last1 = Fitzgerald | date = 14 May 2007 | title = Learning Ruby | edition = First | publisher = [[O'Reilly Media]] | page = [https://archive.org/details/learningruby0000fitz/page/255 255] | isbn = 978-0-596-52986-4 | url = https://archive.org/details/learningruby0000fitz/page/255 }}
{{refend}}

== External links ==
{{Wikiquote}}
{{Commons category|Ruby programming language}}
{{Wikiversity|Topic:Ruby}}

* {{official website|https://www.ruby-lang.org/en/}}
* [https://docs.ruby-lang.org/ Ruby documentation]

{{Ruby programming language}}
{{Programming languages}}
{{FOSS}}
{{ISO standards}}
{{Authority control}}

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