NEWS for Ruby 2.7.0

This document is a list of user visible feature changes made between releases 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)

Changes since the 2.6.0 release

Language changes

Pattern matching

The spec of keyword arguments is changed towards 3.0

Numbered parameter

proc/lambda without block is deprecated

Other miscellaneous changes

Core classes updates (outstanding ones only)

Array
New method
Comparable
Modified method
  • Comparable#clamp now accepts a Range argument. [Feature #14784]

    -1.clamp(0..2) #=> 0
     1.clamp(0..2) #=> 1
     3.clamp(0..2) #=> 2
    
Complex
New method
  • Added Complex#<=>. So 0 <=> 0i will not raise NoMethodError. [Bug #15857]

Dir
Modified methods
  • Dir.glob and Dir.[] no longer allow NUL-separated glob pattern. Use Array instead. [Feature #14643]

Encoding
New encoding
  • Added new encoding CESU-8 [Feature #15931]

Enumerable
New methods
  • Added Enumerable#filter_map. [Feature #15323]

    [1, 2, 3].filter_map {|x| x.odd? ? x.to_s : nil } #=> ["1", "3"]
    
  • Added Enumerable#tally. [Feature #11076]

    ["A", "B", "C", "B", "A"].tally #=> {"A"=>2, "B"=>2, "C"=>1}
    
Enumerator
New methods
  • Added Enumerator.produce to generate Enumerator from any custom data-transformation. [Feature #14781]

    require 'date'
    dates = Enumerator.produce(Date.today, &:succ) #=> infinite sequence of dates
    dates.detect(&:tuesday?) #=> next tuesday
    
  • Added Enumerator::Lazy#eager that generates a non-lazy enumerator from a lazy enumerator. [Feature #15901]

    a = %w(foo bar baz)
    e = a.lazy.map {|x| x.upcase }.map {|x| x + "!" }.eager
    p e.class               #=> Enumerator
    p e.map {|x| x + "?" }  #=> ["FOO!?", "BAR!?", "BAZ!?"]
    
  • Added Enumerator::Yielder#to_proc so that a Yielder object can be directly passed to another method as a block argument. [Feature #15618]

Fiber
New method
File
Modified method
  • File.extname now returns a dot string at a name ending with a dot on non-Windows platforms. [Bug #15267]

    File.extname("foo.") #=> "."
    
FrozenError
New method
GC
New method
  • Added GC.compact method for compacting the heap. This function compacts live objects in the heap so that fewer pages may be used, and the heap may be more CoW friendly. [Feature #15626]

    Details on the algorithm and caveats can be found here: bugs.ruby-lang.org/issues/15626

IO
New method
Integer
Modified method
  • Integer#[] now supports range operation. [Feature #8842]

    0b01001101[2, 4]  #=> 0b0011
    0b01001100[2..5]  #=> 0b0011
    0b01001100[2...6] #=> 0b0011
        ^^^^
NilClass / TrueClass / FalseClass
Modified methods
Module
New methods
  • Added Module#const_source_location to retrieve the location where a constant is defined. [Feature #10771]

  • Added Module#ruby2_keywords for marking a method as passing keyword arguments through a regular argument splat, useful when delegating all arguments to another method in a way that can be backwards compatible with older Ruby versions. [Bug #16154]

Modified methods
ObjectSpace::WeakMap
Modified method
Regexp
Modified method
RubyVM
Removed method
  • RubyVM.resolve_feature_path moved to $LOAD_PATH.resolve_feature_path. [Feature #15903] [Feature #15230]

String
Unicode
  • Update Unicode version and Emoji version from 11.0.0 to 12.0.0. [Feature #15321]

  • Update Unicode version to 12.1.0, adding support for U+32FF SQUARE ERA NAME REIWA. [Feature #15195]

  • Update Unicode Emoji version to 12.1 [Feature #16272]

Time
New methods
Modified method
UnboundMethod
New method
  • Added UnboundMethod#bind_call method. [Feature #15955]

    umethod.bind_call(obj, ...) is semantically equivalent to umethod.bind(obj).call(...). This idiom is used in some libraries to call a method that is overridden. The added method does the same without allocation of intermediate Method object.

    class Foo
      def add_1(x)
        x + 1
      end
    end
    class Bar < Foo
      def add_1(x) # override
        x + 2
      end
    end
    
    obj = Bar.new
    p obj.add_1(1) #=> 3
    p Foo.instance_method(:add_1).bind(obj).call(1) #=> 2
    p Foo.instance_method(:add_1).bind_call(obj, 1) #=> 2
    
$LOAD_PATH
New method
  • Added $LOAD_PATH.resolve_feature_path. [Feature #15903] [Feature #15230]

Stdlib updates (outstanding ones only)

Bundler
CGI
CSV
Date
Delegator
  • Object#DelegateClass accepts a block and module_evals it in the context of the returned class, similar to Class.new and Struct.new.

ERB
  • Prohibit marshaling ERB instance.

IRB
  • Introduce syntax highlight inspired by pry.gem to Binding#irb source lines, REPL input, and inspect output of some core-class objects.

  • Introduce multiline mode by Reline.

  • Show documents when completion.

  • Enable auto indent and save/load history by default.

Net::FTP
Net::IMAP
  • Add Server Name Indication (SNI) support. [Feature #15594]

open-uri
  • Warn open-uri's “open” method at Kernel. Use URI.open instead. [Misc #15893]

  • The default charset of text/* media type is UTF-8 instead of ISO-8859-1. [Bug #15933]

OptionParser
  • Now show “Did you mean?” for unknown option. [Feature #16256]

    test.rb:

    require 'optparse'
    OptionParser.new do |opts|
      opts.on("-f", "--foo", "foo") {|v| }
      opts.on("-b", "--bar", "bar") {|v| }
      opts.on("-c", "--baz", "baz") {|v| }
    end.parse!
    

    example:

    $ ruby test.rb --baa
    Traceback (most recent call last):
    test.rb:7:in `<main>': invalid option: --baa (OptionParser::InvalidOption)
    Did you mean?  baz
                   bar
Pathname
Racc
  • Merge 1.4.15 from upstream repository and added cli of racc.

Reline
  • New stdlib that is compatible with readline stdlib by pure Ruby and also has a multiline mode.

REXML
RSS
RubyGems
StringScanner

Compatibility issues (excluding feature bug fixes)

Proc
  • Proc#to_s format was changed. [Feature #16101]

Stdlib compatibility issues (excluding feature bug fixes)

pathname
  • Kernel#Pathname when called with a Pathname argument now returns the argument instead of creating a new Pathname. This is more similar to other Kernel methods, but can break code that modifies the return value and expects the argument not to be modified.

profile.rb, Profiler__
  • Removed from standard library. No one maintains it from Ruby 2.0.0.

C API updates

Implementation improvements

Fiber
  • Allow selecting different coroutine implementation by using `–with-coroutine=`, e.g.

    ./configure --with-coroutine=ucontext
    ./configure --with-coroutine=copy
  • Replace previous stack cache with fiber pool cache. The fiber pool allocates many stacks in a single memory region. Stack allocation becomes O(log N) and fiber creation is amortized O(1). Around 10x performance improvement was measured in micro-benchmarks.

File
  • File.realpath now uses realpath(3) on many platforms, which can significantly improve performance.

Hash
  • Change data structure of small Hash objects. [Feature #15602]

Monitor
  • Monitor class is written in C-extension. [Feature #16255]

Thread
  • VM stack memory allocation is now combined with native thread stack, improving thread allocation performance and reducing allocation related failures. ~10x performance improvement was measured in micro-benchmarks.

JIT
  • JIT-ed code is recompiled to less-optimized code when an optimization assumption is invalidated.

  • Method inlining is performed when a method is considered as pure. This optimization is still experimental and many methods are NOT considered as pure yet.

  • Default value of --jit-max-cache is changed from 1,000 to 100

  • Default value of --jit-min-calls is changed from 5 to 10,000

Miscellaneous changes