NEWS for Ruby 3.2.0

This document is a list of user-visible feature changes
since the 3.1.0 release, except for bug fixes.

Note that each entry is kept to a minimum, see links for details.

Language changes

• Anonymous rest and keyword rest arguments can now be passed as
  arguments, instead of just used in method parameters.
  [Feature #18351]

  def foo(*)
    bar(*)
  end
  def baz(**)
    quux(**)
  end

• A proc that accepts a single positional argument and keywords will
  no longer autosplat. [Bug #18633]

  proc{|a, **k| a}.call([1, 2])
  # Ruby 3.1 and before
  # => 1
  # Ruby 3.2 and after
  # => [1, 2]

• Constant assignment evaluation order for constants set on explicit
  objects has been made consistent with single attribute assignment
  evaluation order. With this code:

  foo::BAR = baz

  foo is now called before baz. Similarly, for multiple assignments
  to constants, left-to-right evaluation order is used. With this
  code:

  foo1::BAR1, foo2::BAR2 = baz1, baz2

  The following evaluation order is now used:

  1. foo1
  2. foo2
  3. baz1
  4. baz2

  [Bug #15928]

• "Find pattern" is no longer experimental.
  [Feature #18585]

• Methods taking a rest parameter (like *args) and wishing to delegate keyword
  arguments through foo(*args) must now be marked with ruby2_keywords
  (if not already the case). In other words, all methods wishing to delegate
  keyword arguments through *args must now be marked with ruby2_keywords,
  with no exception. This will make it easier to transition to other ways of
  delegation once a library can require Ruby 3+. Previously, the ruby2_keywords
  flag was kept if the receiving method took *args, but this was a bug and an
  inconsistency. A good technique to find the potentially-missing ruby2_keywords
  is to run the test suite, for where it fails find the last method which must
  receive keyword arguments, use puts nil, caller, nil there, and check each
  method/block on the call chain which must delegate keywords is correctly marked
  as ruby2_keywords. [Bug #18625] [Bug #16466]

  def target(**kw)
  end
  
  # Accidentally worked without ruby2_keywords in Ruby 2.7-3.1, ruby2_keywords
  # needed in 3.2+. Just like (*args, **kwargs) or (...) would be needed on
  # both #foo and #bar when migrating away from ruby2_keywords.
  ruby2_keywords def bar(*args)
    target(*args)
  end
  
  ruby2_keywords def foo(*args)
    bar(*args)
  end
  
  foo(k: 1)

• eval and related methods are able to generate code coverage. Enabled using
  Coverage.setup(:all) or Coverge.setup(eval: true). [Feature #19008]

• Coverage.supported?(mode) enables detection of what coverage modes are
  supported. [Feature #19026]

Command line options

Core classes updates

Note: We're only listing outstanding class updates.

• Fiber

  • Introduce Fiber.[] and Fiber.[]= for inheritable fiber storage.
    Introduce Fiber#storage and Fiber#storage= (experimental) for
    getting and resetting the current storage. Introduce
    Fiber.new(storage:) for setting the storage when creating a
    fiber. [Feature #19078]

    Existing Thread and Fiber local variables can be tricky to use.
    Thread local variables are shared between all fibers, making it
    hard to isolate, while Fiber local variables can be hard to
    share. It is often desirable to define unit of execution
    ("execution context") such that some state is shared between all
    fibers and threads created in that context. This is what Fiber
    storage provides.

    def log(message)
      puts "#{Fiber[:request_id]}: #{message}"
    end
    
    def handle_requests
      while request = read_request
        Fiber.schedule do
          Fiber[:request_id] = SecureRandom.uuid
    
          request.messages.each do |message|
            Fiber.schedule do
              log("Handling #{message}") # Log includes inherited request_id.
            end
          end
        end
      end
    end

    You should generally consider Fiber storage for any state which
    you want to be shared implicitly between all fibers and threads
    created in a given context, e.g. a connection pool, a request
    id, a logger level, environment variables, configuration, etc.

• Fiber::Scheduler

  • Introduce Fiber::Scheduler#io_select for non-blocking IO.select.
    [Feature #19060]

• IO

  • Introduce IO#timeout= and IO#timeout which can cause
    IO::TimeoutError to be raised if a blocking operation exceeds the
    specified timeout. [Feature #18630] Start implementing IO#timeout #8662

    STDIN.timeout = 1
    STDIN.read # => Blocking operation timed out! (IO::TimeoutError)

• UNIXSocket

  • Add support for UNIXSocket on Windows. Emulate anonymous sockets. Add
    support for File.socket? and File::Stat#socket? where possible.
    [Feature #19135]

• Class

  • Class#attached_object, which returns the object for which
    the receiver is the singleton class. Raises TypeError if the
    receiver is not a singleton class.
    [Feature #12084]

    class Foo; end
    
    Foo.singleton_class.attached_object        #=> Foo
    Foo.new.singleton_class.attached_object    #=> #<Foo:0x000000010491a370>
    Foo.attached_object                        #=> TypeError: `Foo' is not a singleton class
    nil.singleton_class.attached_object        #=> TypeError: `NilClass' is not a singleton class

• Data

  • New core class to represent simple immutable value object. The class is
    similar to Struct and partially shares an implementation, but has more
    lean and strict API. [Feature #16122]

• Encoding

  • Encoding#replicate has been deprecated and will be removed in 3.3. [Feature #18949]
  • The dummy Encoding::UTF_16 and Encoding::UTF_32 encodings no longer
    try to dynamically guess the endian based on a byte order mark.
    Use Encoding::UTF_16BE/UTF_16LE and Encoding::UTF_32BE/UTF_32LE instead.
    This change speeds up getting the encoding of a String. [Feature #18949]

• Enumerator

  • Enumerator.product has been added. Enumerator::Product is the implementation. [Feature #18685]

• Exception

  • Exception#detailed_message has been added.
    The default error printer calls this method on the Exception object
    instead of #message. [Feature #18564]

• Hash

  • Hash#shift now always returns nil if the hash is
    empty, instead of returning the default value or
    calling the default proc. [Bug #16908]

• Integer

  • Integer#ceildiv has been added. [Feature #18809]

• Kernel

  • Kernel#binding raises RuntimeError if called from a non-Ruby frame
    (such as a method defined in C). [Bug #18487]

• MatchData

  • MatchData#byteoffset has been added. [Feature #13110]
  • MatchData#deconstruct has been added. [Feature #18821]
  • MatchData#deconstruct_keys has been added. [Feature #18821]

• Module

  • Module.used_refinements has been added. [Feature #14332]
  • Module#refinements has been added. [Feature #12737]
  • Module#const_added has been added. [Feature #17881]
  • Module#undefined_instance_methods has been added. [Feature #12655]

• Proc

  • Proc#dup returns an instance of subclass. [Bug #17545]
  • Proc#parameters now accepts lambda keyword. [Feature #15357]

• Process

  • Added RLIMIT_NPTS constant to FreeBSD platform

• Regexp

  • Regexp.new now supports passing the regexp flags not only as an Integer,
    but also as a String. Unknown flags raise ArgumentError.
    Otherwise, anything other than true, false, nil or Integer will be warned.
    [Feature #18788]

  • Regexp.timeout= has been added. Also, Regexp.new new supports timeout keyword.
    See [Feature #17837]

• Refinement

  • Refinement#refined_class has been added. [Feature #12737]

• RubyVM::AbstractSyntaxTree

  • Add error_tolerant option for parse, parse_file and of. [Feature #19013]
    With this option

    1. SyntaxError is suppressed
    2. AST is returned for invalid input
    3. end is complemented when a parser reachs to the end of input but end is insufficient
    4. end is treated as keyword based on indent

    # Without error_tolerant option
    root = RubyVM::AbstractSyntaxTree.parse(<<~RUBY)
    def m
      a = 10
      if
    end
    RUBY
    # => <internal:ast>:33:in `parse': syntax error, unexpected `end' (SyntaxError)
    
    # With error_tolerant option
    root = RubyVM::AbstractSyntaxTree.parse(<<~RUBY, error_tolerant: true)
    def m
      a = 10
      if
    end
    RUBY
    p root # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-4:3>
    
    # `end` is treated as keyword based on indent
    root = RubyVM::AbstractSyntaxTree.parse(<<~RUBY, error_tolerant: true)
    module Z
      class Foo
        foo.
      end
    
      def bar
      end
    end
    RUBY
    p root.children[-1].children[-1].children[-1].children[-2..-1]
    # => [#<RubyVM::AbstractSyntaxTree::Node:CLASS@2:2-4:5>, #<RubyVM::AbstractSyntaxTree::Node:DEFN@6:2-7:5>]

  • Add keep_tokens option for parse, parse_file and of. Add #tokens and #all_tokens
    for RubyVM::AbstractSyntaxTree::Node [Feature #19070]

    root = RubyVM::AbstractSyntaxTree.parse("x = 1 + 2", keep_tokens: true)
    root.tokens # => [[0, :tIDENTIFIER, "x", [1, 0, 1, 1]], [1, :tSP, " ", [1, 1, 1, 2]], ...]
    root.tokens.map{_1[2]}.join # => "x = 1 + 2"

• Set

  • Set is now available as a built-in class without the need for require "set". [Feature #16989]
    It is currently autoloaded via the Set constant or a call to Enumerable#to_set.

• Socket

  • Added the following constants for supported platforms.
    • SO_INCOMING_CPU
    • SO_INCOMING_NAPI_ID
    • SO_RTABLE
    • SO_SETFIB
    • SO_USER_COOKIE
    • TCP_KEEPALIVE
    • TCP_CONNECTION_INFO

• String

  • String#byteindex and String#byterindex have been added. [Feature #13110]
  • Update Unicode to Version 15.0.0 and Emoji Version 15.0. [Feature #18639]
    (also applies to Regexp)
  • String#bytesplice has been added. [Feature #18598]

• Struct

  • A Struct class can also be initialized with keyword arguments
    without keyword_init: true on Struct.new [Feature #16806]

• Time

  • Time#deconstruct_keys is added, allowing to use Time instances
    in pattern-matching expressions [Feature #19071]

• SyntaxError

  • SyntaxError#path has been added. [Feature #19138]

• TracePoint

  • TracePoint#binding now returns nil for c_call/c_return TracePoints.
    [Bug #18487]
  • TracePoint#enable target_thread keyword argument now defaults to the
    current thread if target and target_line keyword arguments are not
    passed. [Bug #16889]

Stdlib updates

Note: Most of these updates are superseded by those in #8029.

• ERB

  • -S option is removed from erb command.

• FileUtils

  • Add FileUtils.ln_sr method and relative: option to FileUtils.ln_s.
    [Feature #18925]

• SyntaxSuggest

  • The feature of syntax_suggest formerly dead_end is integrated in Ruby.
    [Feature #18159]
  • Update once syntax_suggest CLI doesn't work when it is a standard gem ruby/syntax_suggest#215 is addressed.

• The following default gems are updated.

  • RubyGems 3.4.0.dev
  • benchmark 0.2.1
  • bigdecimal 3.1.3
  • bundler 2.4.0.dev
  • cgi 0.3.6
  • date 3.3.0
  • delegate 0.3.0
  • did_you_mean 1.6.2
  • digest 3.1.1
  • drb 2.1.1
  • erb 4.0.2
  • error_highlight 0.5.1
  • etc 1.4.1
  • fcntl 1.0.2
  • fiddle 1.1.1
  • fileutils 1.7.0
  • forwardable 1.3.3
  • getoptlong 0.2.0
  • io-console 0.5.11
  • io-nonblock 0.2.0
  • io-wait 0.3.0.pre
  • ipaddr 1.2.5
  • irb 1.5.1
  • json 2.6.2
  • logger 1.5.2
  • mutex_m 0.1.2
  • net-http 0.3.1
  • net-protocol 0.2.0
  • nkf 0.1.2
  • open-uri 0.3.0
  • openssl 3.1.0.pre
  • optparse 0.3.0
  • ostruct 0.5.5
  • pathname 0.2.1
  • pp 0.4.0
  • pstore 0.1.2
  • psych 5.0.0
  • racc 1.6.1
  • rdoc 6.5.0
  • reline 0.3.1
  • resolv 0.2.2
  • securerandom 0.2.1
  • set 1.0.3
  • stringio 3.0.3
  • syntax_suggest 1.0.1
  • timeout 0.3.1
  • tmpdir 0.1.3
  • tsort 0.1.1
  • un 0.2.1
  • uri 0.12.0
  • win32ole 1.8.9
  • zlib 3.0.0

• The following bundled gems are updated.

  • minitest 5.16.3
  • power_assert 2.0.2
  • test-unit 3.5.5
  • net-ftp 0.2.0
  • net-imap 0.3.1
  • net-pop 0.1.2
  • net-smtp 0.3.3
  • rbs 2.8.1
  • typeprof 0.21.3
  • debug 1.7.0

Compatibility issues

Note: Excluding feature bug fixes.

Removed constants

The following deprecated constants are removed.

• Fixnum and Bignum [Feature #12005]
• Random::DEFAULT [Feature #17351]
• Struct::Group
• Struct::Passwd

Removed methods

The following deprecated methods are removed.

• Dir.exists? [Feature #17391]
• File.exists? [Feature #17391]
• Kernel#=~ [Feature #15231]
• Kernel#taint, Kernel#untaint, Kernel#tainted?
  [Feature #16131]
• Kernel#trust, Kernel#untrust, Kernel#untrusted?
  [Feature #16131]