# NEWS for Ruby 2.8.0 (tentative; to be 3.0.0) This document is a list of user visible feature changes since the **2.7.0** release, except for bug fixes. Note that each entry is kept so brief that no reason behind or reference information is supplied with. For a full list of changes with all sufficient information, see the ChangeLog file or Redmine (e.g. `https://bugs.ruby-lang.org/issues/$FEATURE_OR_BUG_NUMBER`). ## Language changes * Keyword arguments are now separated from positional arguments. Code that resulted in deprecation warnings in Ruby 2.7 will now result in ArgumentError or different behavior. [[Feature #14183]] * Procs accepting a single rest argument and keywords are no longer subject to autosplatting. This now matches the behavior of Procs accepting a single rest argument and no keywords. [[Feature #16166]] ```ruby pr = proc{|*a, **kw| [a, kw]} pr.call([1]) # 2.7 => [[1], {}] # 3.0 => [[[1]], {}] pr.call([1, {a: 1}]) # 2.7 => [[1], {:a=>1}] # and deprecation warning # 3.0 => [[[1, {:a=>1}]], {}] ``` * $SAFE is now a normal global variable with no special behavior. [[Feature #16131]] * yield in singleton class definitions in methods is now a SyntaxError instead of a warning. yield in a class definition outside of a method is now a SyntaxError instead of a LocalJumpError. [[Feature #15575]] * Find pattern is added. [[Feature #16828]] ```ruby case ["a", 1, "b", "c", 2, "d", "e", "f", 3] in [*pre, String => x, String => y, *post] p pre #=> ["a", 1] p x #=> "b" p y #=> "c" p post #=> [2, "d", "e", "f", 3] end ``` * Rightward assignment statement is added. [EXPERIMENTAL] [[Feature #15921]] ```ruby fib(10) => x ``` * Endless method definition is added. [EXPERIMENTAL] [[Feature #16746]] ```ruby def square(x) = x * x ``` ## Command line options ### `--help` option When the environment variable `RUBY_PAGER` or `PAGER` is present and has non-empty value, and the standard input and output are tty, `--help` option shows the help message via the pager designated by the value. [[Feature #16754]] ## Core classes updates Outstanding ones only. * Dir * Modified method * Dir.glob and Dir.[] now sort the results by default, and accept `sort:` keyword option. [[Feature #8709]] * Hash * Modified method * Hash#transform_keys now accepts a hash that maps keys to new keys. [[Feature #16274]] * Kernel * Modified method * Kernel#clone when called with `freeze: false` keyword will call #initialize_clone with the `freeze: false` keyword. [[Bug #14266]] * Kernel#eval when called with two arguments will use "(eval)" for `__FILE__` and 1 for `__LINE__` in the evaluated code. [[Bug #4352]] * Module * Modified method * Module#include now includes the arguments in modules and classes that have already included or prepended the receiver, mirroring the behavior if the arguments were included in the receiver before the other modules and classes included or prepended the receiver. [[Feature #9573]] * Symbol * Modified method * Symbol#to_proc now returns a lambda Proc. [[Feature #16260]] ## Stdlib updates Outstanding ones only. * RubyGems * Update to RubyGems 3.2.0.pre1 * Bundler * Update to Bundler 2.2.0.dev * Net::HTTP * New method * Add Net::HTTP#verify_hostname= and Net::HTTP#verify_hostname to skip hostname verification. [[Feature #16555]] * Modified method * Net::HTTP.get, Net::HTTP.get_response, and Net::HTTP.get_print can take request headers as a Hash in the second argument when the first argument is a URI. ## Compatibility issues Excluding feature bug fixes. * Regexp literals are frozen [[Feature #8948]] [[Feature #16377]] ```ruby /foo/.frozen? #=> true ``` * Bundled gems * net-telnet and xmlrpc have been removed from the bundled gems. If you are interested in maintaining them, please comment on your plan to https://github.com/ruby/xmlrpc or https://github.com/ruby/net-telnet. * EXPERIMENTAL: Hash#each consistently yields a 2-element array [[Bug #12706]] * Now `{ a: 1 }.each(&->(k, v) { })` raises an ArgumentError due to lambda's arity check. * This is experimental; if it brings a big incompatibility issue, it may be reverted until 2.8/3.0 release. * When writing to STDOUT redirected to a closed pipe, no broken pipe error message will be shown now. [[Feature #14413]] * `TRUE`/`FALSE`/`NIL` constants are no longer defined. ## Stdlib compatibility issues Excluding feature bug fixes. ## C API updates * C API functions related to $SAFE have been removed. [[Feature #16131]] * C API header file `ruby/ruby.h` was split. [[GH-2991]] Should have no impact on extension libraries, but users might experience slow compilations. ## Implementation improvements * The number of hashes allocated when using a keyword splat in a method call has been reduced to a maximum of 1, and passing a keyword splat to a method that accepts specific keywords does not allocate a hash. ## Miscellaneous changes * Methods using `ruby2_keywords` will no longer keep empty keyword splats, those are now removed just as they are for methods not using `ruby2_keywords`. * Taint deprecation warnings are now issued in regular mode in addition to verbose warning mode. [[Feature #16131]] * When an exception is caught in the default handler, the error message and backtrace are printed in order from the innermost. [[Feature #8661]] [Bug #4352]: https://bugs.ruby-lang.org/issues/4352 [Feature #8661]: https://bugs.ruby-lang.org/issues/8661 [Feature #8709]: https://bugs.ruby-lang.org/issues/8709 [Feature #8948]: https://bugs.ruby-lang.org/issues/8948 [Feature #9573]: https://bugs.ruby-lang.org/issues/9573 [Feature #14183]: https://bugs.ruby-lang.org/issues/14183 [Bug #14266]: https://bugs.ruby-lang.org/issues/14266 [Feature #14413]: https://bugs.ruby-lang.org/issues/14413 [Feature #15575]: https://bugs.ruby-lang.org/issues/15575 [Feature #16131]: https://bugs.ruby-lang.org/issues/16131 [Feature #16166]: https://bugs.ruby-lang.org/issues/16166 [Feature #16260]: https://bugs.ruby-lang.org/issues/16260 [Feature #16274]: https://bugs.ruby-lang.org/issues/16274 [Feature #16377]: https://bugs.ruby-lang.org/issues/16377 [Bug #12706]: https://bugs.ruby-lang.org/issues/12706 [Feature #15921]: https://bugs.ruby-lang.org/issues/15921 [Feature #16555]: https://bugs.ruby-lang.org/issues/16555 [Feature #16746]: https://bugs.ruby-lang.org/issues/16746 [Feature #16754]: https://bugs.ruby-lang.org/issues/16754 [GH-2991]: https://github.com/ruby/ruby/pull/2991