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).
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]
Arguments forwarding (...) now supports leading arguments.
[Feature #16378]
def method_missing(meth, ...) send(:"do_#{meth}", ...) end
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]
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. C-API methods related to $SAFE have been removed. [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]
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
When a class variable is overtaken by the same definition in an ancestor class/module, a RuntimeError is now raised (previously, it only issued a warning in verbose mode. Additionally, accessing a class variable from the toplevel scope is now a RuntimeError. [Bug #14541]
Rightward assignment statement is added. [EXPERIMENTAL] [Feature #15921]
fib(10) => x
Endless method definition is added. [EXPERIMENTAL] [Feature #16746]
def square(x) = x * x
Interpolated String literals are no longer frozen
when # frozen-string-literal: true is used. [Feature #17104]
RBS is introduced. It is a type definition language for Ruby programs.
--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]
Outstanding ones only.
Modified method
Dir.glob and Dir.[] now sort the results by default,
and accept sort: keyword option. [Feature #8709]
New method
ENV.except, which returns a hash excluding the given keys and their values. [Feature #15822]
Modified method
Hash#transform_keys now accepts a hash that maps keys to new keys. [Feature #16274]
New method
Hash#except, which returns a hash excluding the given keys and their values. [Feature #15822]
Modified method
Kernel#clone when called with
freeze: false keyword will call
#initialize_clone with the freeze: false keyword.
[Bug #14266]
Kernel#clone when called with
freeze: true keyword will call #initialize_clone
with the freeze: true keyword, and will return a frozen copy
even if the receiver is unfrozen. [Feature #16175]
Kernel#eval when called with two
arguments will use "(eval)" for __FILE__ and 1 for
__LINE__ in the evaluated code. [Bug #4352]
Kernel#lambda now warns if called without a literal block. [Feature #15973]
Modified method
Module#include and prepend now affect classes and modules 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]
class C; end module M1; end module M2; end C.include M1 M1.include M2 p C.ancestors #=> [C, M1, M2, Object, Kernel, BasicObject]
All Range objects are frozen. [Feature #15504]
Introduce Thread#scheduler for intercepting blocking
operations and Thread.scheduler for accessing the current
scheduler. See doc/scheduler.md for more details. [Feature #16786]
Thread#blocking? tells whether the current execution context
is blocking. [Feature
#16786]
Thread#join invokes the scheduler hooks
block/unblock in a non-blocking execution
context. [Feature
#16786]
Mutex is now acquired per-Fiber instead of
per-Thread. This change should be compatible for essentially
all usages and avoids blocking when using a scheduler. [Feature #16792]
Fiber.new(blocking: true/false) allows you to create
non-blocking execution contexts. [Feature #16786]
Fiber#blocking? tells whether the fiber is non-blocking. [Feature #16786]
Fiber#backtrace & Fiber#backtrace_locations
provide per-fiber backtrace. [Feature #16815]
Kernel.sleep(...) invokes the scheduler hook
#kernel_sleep(...) in a non-blocking execution context. [Feature #16786]
IO#nonblock? now defaults to true. [Feature #16786]
IO#wait_readable, IO#wait_writable,
IO#read, IO#write and other related methods
(e.g. #puts, #gets) may invoke the scheduler hook
#io_wait(io, events, timeout) in a non-blocking execution
context. [Feature
#16786]
ConditionVariable#wait may now invoke the
block/unblock scheduler hooks in a non-blocking
context. [Feature
#16786]
Queue#pop, SizedQueue#push and related methods
may now invoke the block/unblock scheduler hooks
in a non-blocking context. [Feature #16786]
new class to enable parallel execution. See doc/ractor.md for more details.
Modified method
Symbol#to_proc now returns a lambda Proc. [Feature #16260]
New method
Object#name, which returns the name of the symbol if it is named. The returned string cannot be modified. [Feature #16150]
Modified method
Warning#warn now supports a category kwarg. [Feature #17122]
Outstanding ones only.
RubyGems
Update to RubyGems 3.2.0.rc.1
Bundler
Update to Bundler 2.2.0.rc.1
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. [Feature #16686]
IRB
Update to IRB 1.2.6
OpenStruct
Initialization no longer lazy [Bug #12136]
Builtin methods can now be overridden safely. [Bug #15409]
Implementation uses only methods ending with !.
Ractor compatible.
Improved support for YAML [Bug #8382]
Use officially discouraged. Read "Caveats" section.
Reline
Update to Reline 0.1.5
Socket
TCPSocket.new now supports resolv_timeout. [Feature #17134]
ruby # it raises SocketError if name resolution is not finished
within resolve_timeout. tcp_socket =
TCPSocket.new("example.com", 80, resolv_timeout: 10)
Excluding feature bug fixes.
Regexp literals are frozen [Feature #8948] [Feature #16377]
/foo/.frozen? #=> true
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.
Integer#zero? overrides Numeric#zero? for
optimization. [Misc
#16961]
Default gems
The following libraries are promoted the default gems from stdlib.
abbrev
base64
English
erb
find
io-nonblock
io-wait
net-ftp
net-http
net-imap
net-protocol
nkf
open-uri
optparse
resolv
resolv-replace
rinda
securerandom
set
shellwords
tempfile
time
tmpdir
tsort
weakref
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 github.com/ruby/xmlrpc or github.com/ruby/net-telnet.
SDBM have been removed from ruby standard library. [Bug #8446]
The issues of sdbm will be handled at github.com/ruby/sdbm
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.
Memory view interface [EXPERIMENTAL]
The memory view interface is a C-API set to exchange a raw memory area, such as a numeric array and a bitmap image, between extension libraries. The extension libraries can share also the metadata of the memory area that consists of the shape, the element format, and so on. Using these kinds of metadata, the extension libraries can share even a multidimensional array appropriately. This feature is designed by referring to Python's buffer protocol. [Feature #13767] [Feature #14722]
New method cache mechanism for Ractor [Feature #16614]
Inline method caches pointed from ISeq can be accessed by multiple Ractors in parallel and synchronization is needed even for method caches. However, such synchronization can be overhead so introducing new inline method cache mehanisms, (1) Disposable inline method cache (2) per-Class method cache and (3) new invalidation mechanism. (1) can avoid per-method call syncrhonization because it only use atomic operations. See the ticket for more details.
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.
super is optimized when the same type of method is called in
the previous call if it's not refinements or an attr reader or writer.
Native functions shared by multiple methods are deduplicated on JIT compaction.
Decrease code size of hot paths by some optimizations and partitioning cold paths.
Not only pure Ruby methods but also some C methods skip pushing a method frame.
Kernel#class, Integer#zero?
Always generate appropriate code for ==, nil?,
and ! calls depending on a receiver class.
Optimize instance variable access in some core classes like Hash and their subclasses
Eliminate VM register access on a method return
Optimize C method call a little
RBS is a new language for type definition of Ruby programs. It allows writing types of classes and modules with advanced types including union types, overloading, generics, and interface types for duck typing.
Ruby ships with type definitions for core/stdlib classes.
rbs gem is bundled to load and process RBS files.
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]