NEWS for Ruby 3.1.0¶ ↑
This document is a list of user-visible feature changes since the 3.0.0 release, except for bug fixes.
Note that each entry is kept to a minimum, see links for details.
Language changes¶ ↑
-
The block argument can now be anonymous if the block will only be passed to another method. [Feature #11256]
def foo(&) bar(&) end
-
Pin operator now takes an expression. [Feature #17411]
Prime.each_cons(2).lazy.find_all{_1 in [n, ^(n + 2)]}.take(3).to_a #=> [[3, 5], [5, 7], [11, 13]]
-
Pin operator now supports instance, class, and global variables. [Feature #17724]
@n = 5 Prime.each_cons(2).lazy.find{_1 in [n, ^@n]} #=> [3, 5]
-
One-line pattern matching is no longer experimental.
-
Parentheses can be omitted in one-line pattern matching. [Feature #16182]
[0, 1] => _, x {y: 2} => y: x #=> 1 y #=> 2
-
Multiple assignment evaluation order has been made consistent with single assignment evaluation order. With single assignment, Ruby uses a left-to-right evaluation order. With this code:
foo[0] = bar
The following evaluation order is used:
-
foo
-
bar
-
[]=
called on the result offoo
In Ruby before 3.1.0, multiple assignment did not follow this evaluation order. With this code:
foo[0], bar.baz = a, b
Versions of Ruby before 3.1.0 would evaluate in the following order
-
a
-
b
-
foo
-
[]=
called on the result offoo
-
bar
-
baz=
called on the result ofbar
Starting in Ruby 3.1.0, the evaluation order is now consistent with single assignment, with the left-hand side being evaluated before the right-hand side:
-
foo
-
bar
-
a
-
b
-
[]=
called on the result offoo
-
baz=
called on the result ofbar
-
-
Values in
Hash
literals and keyword arguments can be omitted. [Feature #14579]For example,
-
{x:, y:}
is a syntax sugar of{x: x, y: y}
. -
foo(x:, y:)
is a syntax sugar offoo(x: x, y: y)
.
Constant names, local variable names, and method names are allowed as key names. Note that a reserved word is considered as a local variable or method name even if it's a pseudo variable name such as
self
. -
-
Non main-Ractors can get instance variables (ivars) of classes/modules if ivars refer to shareable objects. [Feature #17592]
-
A command syntax is allowed in endless method definitions, i.e., you can now write
def foo = puts "Hello"
. Note thatprivate def foo = puts "Hello"
does not parse. [Feature #17398]
Command line options¶ ↑
-
--disable-gems
is now explicitly declared as “just for debugging”. Never use it in any real-world codebase. [Feature #17684]
Core classes updates¶ ↑
Note: We’re only listing outstanding class updates.
-
-
Array#intersect?
is added. [Feature #15198]
-
-
-
Class#subclasses
, which returns an array of classes directly inheriting from the receiver, not including singleton classes. [Feature #18273]class A; end class B < A; end class C < B; end class D < A; end A.subclasses #=> [D, B] B.subclasses #=> [C] C.subclasses #=> []
-
-
-
Enumerable#compact
is added. [Feature #17312] -
Enumerable#tally
now accepts an optional hash to count. [Feature #17744] -
Enumerable#each_cons
and each_slice to return a receiver. [GH-1509][1, 2, 3].each_cons(2){} # 3.0 => nil # 3.1 => [1, 2, 3] [1, 2, 3].each_slice(2){} # 3.0 => nil # 3.1 => [1, 2, 3]
-
-
-
Enumerator::Lazy#compact
is added. [Feature #17312]
-
-
-
File.dirname
now accepts an optional argument for the level to strip path components. [Feature #12194]
-
-
-
"GC.measure_total_time = true" enables the measurement of
GC
. Measurement can introduce overhead. It is enabled by default.GC.measure_total_time
returns the current setting.GC.stat[:time]
orGC.stat
(:time) returns measured time in milli-seconds. [[Feature #10917]] -
GC.total_time
returns measured time in nano-seconds. [[Feature #10917]]
-
-
-
Integer.try_convert
is added. [Feature #15211]
-
-
-
Kernel#load
now accepts a module as the second argument, and will load the file using the given module as the top-level module. [Feature #6210]
-
-
-
Marshal.load
now accepts afreeze: true
option. All returned objects are frozen except forClass
andModule
instances. Strings are deduplicated. [Feature #18148]
-
-
-
MatchData#match
is added [Feature #18172] -
MatchData#match_length
is added [Feature #18172]
-
-
-
Method#public?, Method#private?, Method#protected?, UnboundMethod#public?, UnboundMethod#private?, UnboundMethod#protected? have been added. [Feature #11689]
-
-
-
Module#prepend
now modifies the ancestor chain if the receiver already includes the argument.Module#prepend
still does not modify the ancestor chain if the receiver has already prepended the argument. [Bug #17423] -
Module#private
, public, protected, and module_function will now return their arguments. If a single argument is given, it is returned. If no arguments are given, nil is returned. If multiple arguments are given, they are returned as an array. [Feature #12495]
-
-
-
Process
._fork is added. This is a core method for fork(2). Do not call this method directly; it is called by existing fork methods:Kernel
.#fork,Process.fork
, andIO.popen
(“-”). Application monitoring libraries can overwrite this method to hook fork events. [Feature #17795]
-
-
-
Passing only keyword arguments to Struct#initialize is warned. You need to use a
Hash
literal to set aHash
to a first member. [Feature #16806] -
StructClass#keyword_init? is added [Feature #18008]
-
-
-
Update Unicode version to 13.0.0 [Feature #17750] and Emoji version to 13.0 [Feature #18029]
-
String#unpack
andString#unpack1
now accept anoffset:
keyword argument to start the unpacking after an arbitrary number of bytes have been skipped. Ifoffset
is outside of the string boundsArgumentError
is raised. [Feature #18254]
-
-
-
Thread#native_thread_id
is added. [Feature #17853]
-
-
-
Thread::Backtrace.limit
, which returns the value to limit backtrace length set by--backtrace-limit
command line option, is added. [Feature #17479]
-
-
-
Thread::Queue.new
now accepts anEnumerable
of initial values. [Feature #17327]
-
-
-
Time.new
now accepts optionalin:
keyword argument for the timezone, as well asTime.at
andTime.now
, so that is now you can omit minor arguments toTime.new
. [Feature #17485]Time.new(2021, 12, 25, in: "+07:00") #=> 2021-12-25 00:00:00 +0700
At the same time, time component strings are converted to integers more strictly now.
Time.new(2021, 12, 25, "+07:30") #=> invalid value for Integer(): "+07:30" (ArgumentError)
Ruby 3.0 or earlier returned probably unexpected result
2021-12-25 07:00:00
, not2021-12-25 07:30:00
nor2021-12-25 00:00:00 +07:30
. -
Time#strftime
supports RFC 3339 UTC for unknown offset local time,-0000
, as%-z
. [Feature #17544]
-
-
-
TracePoint.allow_reentry
is added to allow reenter whileTracePoint
callback. [Feature #15912]
-
-
$LOAD_PATH
-
$LOAD_PATH.resolve_feature_path does not raise. [Feature #16043]
-
-
Fiber
Scheduler-
Add support for
Addrinfo.getaddrinfo
usingaddress_resolve
hook. [Feature #17370] -
Introduce non-blocking
Timeout.timeout
usingtimeout_after
hook. [Feature #17470] -
Introduce new scheduler hooks
io_read
andio_write
along with a low levelIO::Buffer
for zero-copy read/write. [Feature #18020] -
IO
hooksio_wait
,io_read
,io_write
, receive the originalIO
object where possible. [Bug #18003] -
Make
Monitor
fiber-safe. [Bug #17827] -
Replace copy coroutine with pthread implementation. [Feature #18015]
-
-
-
New class which represents a module created by
Module#refine
.include
andprepend
are deprecated, andimport_methods
is added instead. [Bug #17429]
-
Stdlib updates¶ ↑
-
The following default gem are updated.
-
RubyGems 3.3.3
-
base64 0.1.1
-
benchmark 0.2.0
-
bigdecimal 3.1.1
-
bundler 2.3.3
-
cgi 0.3.1
-
csv 3.2.2
-
date 3.2.2
-
did_you_mean 1.6.1
-
digest 3.1.0
-
drb 2.1.0
-
erb 2.2.3
-
error_highlight 0.3.0
-
etc 1.3.0
-
fcntl 1.0.1
-
fiddle 1.1.0
-
fileutils 1.6.0
-
find 0.1.1
-
io-console 0.5.10
-
io-wait 0.2.1
-
ipaddr 1.2.3
-
irb 1.4.1
-
json 2.6.1
-
logger 1.5.0
-
net-http 0.2.0
-
net-protocol 0.1.2
-
nkf 0.1.1
-
open-uri 0.2.0
-
openssl 3.0.0
-
optparse 0.2.0
-
ostruct 0.5.2
-
pathname 0.2.0
-
pp 0.3.0
-
prettyprint 0.1.1
-
psych 4.0.3
-
racc 1.6.0
-
rdoc 6.4.0
-
readline 0.0.3
-
readline-ext 0.1.4
-
reline 0.3.0
-
resolv 0.2.1
-
rinda 0.1.1
-
ruby2_keywords 0.0.5
-
securerandom 0.1.1
-
set 1.0.2
-
stringio 3.0.1
-
strscan 3.0.1
-
tempfile 0.1.2
-
time 0.2.0
-
timeout 0.2.0
-
tmpdir 0.1.2
-
un 0.2.0
-
uri 0.11.0
-
yaml 0.2.0
-
zlib 2.1.1
-
RubyGems 3.3.3
-
base64 0.1.1
-
benchmark 0.2.0
-
bigdecimal 3.1.1
-
bundler 2.3.3
-
cgi 0.3.1
-
csv 3.2.2
-
date 3.2.2
-
did_you_mean 1.6.1
-
digest 3.1.0
-
drb 2.1.0
-
erb 2.2.3
-
error_highlight 0.3.0
-
etc 1.3.0
-
fcntl 1.0.1
-
fiddle 1.1.0
-
fileutils 1.6.0
-
find 0.1.1
-
io-console 0.5.10
-
io-wait 0.2.1
-
ipaddr 1.2.3
-
irb 1.4.1
-
json 2.6.1
-
logger 1.5.0
-
net-http 0.2.0
-
net-protocol 0.1.2
-
nkf 0.1.1
-
open-uri 0.2.0
-
openssl 3.0.0
-
optparse 0.2.0
-
ostruct 0.5.2
-
pathname 0.2.0
-
pp 0.3.0
-
prettyprint 0.1.1
-
psych 4.0.3
-
racc 1.6.0
-
rdoc 6.4.0
-
readline 0.0.3
-
readline-ext 0.1.4
-
reline 0.3.0
-
resolv 0.2.1
-
rinda 0.1.1
-
ruby2_keywords 0.0.5
-
securerandom 0.1.1
-
set 1.0.2
-
stringio 3.0.1
-
strscan 3.0.1
-
tempfile 0.1.2
-
time 0.2.0
-
timeout 0.2.0
-
tmpdir 0.1.2
-
un 0.2.0
-
uri 0.11.0
-
yaml 0.2.0
-
zlib 2.1.1
-
-
The following bundled gems are updated.
-
minitest 5.15.0
-
power_assert 2.0.1
-
rake 13.0.6
-
test-unit 3.5.3
-
rexml 3.2.5
-
rbs 2.0.0
-
typeprof 0.21.1
-
minitest 5.15.0
-
power_assert 2.0.1
-
rake 13.0.6
-
test-unit 3.5.3
-
rexml 3.2.5
-
rbs 2.0.0
-
typeprof 0.21.1
-
-
The following default gems are now bundled gems.
-
net-ftp 0.1.3
-
net-imap 0.2.2
-
net-pop 0.1.1
-
net-smtp 0.3.1
-
matrix 0.4.2
-
prime 0.1.2
-
debug 1.4.0
-
net-ftp 0.1.3
-
net-imap 0.2.2
-
net-pop 0.1.1
-
net-smtp 0.3.1
-
matrix 0.4.2
-
prime 0.1.2
-
debug 1.4.0
-
-
The following gems has been removed from the Ruby standard library.
-
dbm
-
gdbm
-
tracer
-
dbm
-
gdbm
-
tracer
-
-
Coverage measurement now supports suspension. You can use
Coverage.suspend
to stop the measurement temporarily, andCoverage.resume
to restart it. See [Feature #18176] in detail. -
Random::Formatter
is moved to random/formatter.rb, so that you can useRandom#hex
,Random#base64
, and so on without SecureRandom. [Feature #18190]
Compatibility issues¶ ↑
Note: Excluding feature bug fixes.
-
rb_io_wait_readable
,rb_io_wait_writable
andrb_wait_for_single_fd
are deprecated in favour ofrb_io_maybe_wait_readable
,rb_io_maybe_wait_writable
andrb_io_maybe_wait
respectively.rb_thread_wait_fd
andrb_thread_fd_writable
are deprecated. [Bug #18003]
Stdlib compatibility issues¶ ↑
-
ERB#initialize
warnssafe_level
and later arguments even without -w. [Feature #14256] -
lib/debug.rb
is replaced withdebug.gem
-
Kernel#pp
inlib/pp.rb
uses the width ofIO#winsize
by default. This means that the output width is automatically changed depending on your terminal size. [Feature #12913] -
Psych 4.0 changes
Psych.load
assafe_load
by the default. You may need to use Psych 3.3.2 for migrating to this behavior. [Bug #17866]
C API updates¶ ↑
-
Documented. [GH-4815]
-
rb_gc_force_recycle
is deprecated and has been changed to a no-op. [Feature #18290]
Implementation improvements¶ ↑
-
Inline cache mechanism is introduced for reading class variables. [Feature #17763]
-
instance_eval
andinstance_exec
now only allocate a singleton class when required, avoiding extra objects and improving performance. [GH-5146] -
The performance of
Struct
accessors is improved. [GH-5131] -
mandatory_only?
builtin special form to improve performance on builtin methods. [GH-5112] -
Experimental feature Variable Width Allocation in the garbage collector. This feature is turned off by default and can be enabled by compiling Ruby with flag
USE_RVARGC=1
set. [Feature #18045] [Feature #18239]
JIT¶ ↑
-
Rename Ruby 3.0’s
--jit
to--mjit
, and alias--jit
to--yjit
on non-Windows x86-64 platforms and to--mjit
on others.
MJIT¶ ↑
-
The default
--mjit-max-cache
is changed from 100 to 10000. -
JIT-ed code is no longer cancelled when a
TracePoint
for class events is enabled. -
The JIT compiler no longer skips compilation of methods longer than 1000 instructions.
-
--mjit-verbose
and--mjit-warning
output “JIT cancel” when JIT-ed code is disabled becauseTracePoint
orGC.compact
is used.
YJIT: New experimental in-process JIT compiler¶ ↑
New JIT compiler available as an experimental feature. [Feature #18229]
See this blog post introducing the project.
-
Disabled by default, use
--yjit
command-line option to enable YJIT. -
Performance improvements on benchmarks based on real-world software, up to 22% on railsbench, 39% on liquid-render.
-
Fast warm-up times.
-
Limited to Unix-like x86-64 platforms for now.
Static analysis¶ ↑
RBS¶ ↑
-
Generics type parameters can be bounded (PR).
# `T` must be compatible with the `_Output` interface. # `PrettyPrint[String]` is ok, but `PrettyPrint[Integer]` is a type error. class PrettyPrint[T < _Output] interface _Output def <<: (String) -> void end attr_reader output: T def initialize: (T output) -> void end
-
Type aliases can be generic. (PR)
# Defines a generic type `list`. type list[T] = [ T, list[T] ] | nil type str_list = list[String] type int_list = list[Integer]
-
rbs collection has been introduced to manage gems’ RBSs.
-
Many signatures for built-in and standard libraries have been added/updated.
-
It includes many bug fixes and performance improvements too.
See the CHANGELOG.md for more information.
TypeProf¶ ↑
-
Experimental IDE support has been implemented.
-
Many bug fixes and performance improvements since Ruby 3.0.0.
Debugger¶ ↑
-
A new debugger debug.gem is bundled. debug.gem is a fast debugger implementation, and it provides many features like remote debugging, colorful REPL, IDE (VSCode) integration, and more. It replaces
lib/debug.rb
standard library. -
rdbg
command is also installed intobin/
directory to start and control debugging execution.
error_highlight¶ ↑
A built-in gem called error_highlight has been introduced. It shows fine-grained error locations in the backtrace.
Example: title = json[:article][:title]
If json
is nil, it shows:
$ ruby test.rb test.rb:2:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError) title = json[:article][:title] ^^^^^^^^^^
If json[:article]
returns nil, it shows:
$ ruby test.rb test.rb:2:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError) title = json[:article][:title] ^^^^^^^^
This feature is enabled by default. You can disable it by using a command-line option --disable-error_highlight
. See the repository in detail.
IRB Autocomplete and Document Display¶ ↑
The IRB now has an autocomplete feature, where you can just type in the code, and the completion candidates dialog will appear. You can use Tab and Shift+Tab to move up and down.
If documents are installed when you select a completion candidate, the documentation dialog will appear next to the completion candidates dialog, showing part of the content. You can read the full document by pressing Alt+d.
Miscellaneous changes¶ ↑
-
lib/objspace/trace.rb is added, which is a tool for tracing the object allocation. Just by requiring this file, tracing is started immediately. Just by
Kernel#p
, you can investigate where an object was created. Note that just requiring this file brings a large performance overhead. This is only for debugging purposes. Do not use this in production. [Feature #17762] -
Now exceptions raised in finalizers will be printed to
STDERR
, unless$VERBOSE
isnil
. [Feature #17798] -
ruby -run -e httpd
displays URLs to access. [Feature #17847] -
Add
ruby -run -e colorize
to colorize Ruby code usingIRB::Color.colorize_code
.