Editing Ruby (programming language) (section)

=== 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.