NEWS for Ruby 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 to a minimum, see links for details.
Language changes¶ ↑
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Keyword arguments are now separated from positional arguments. Code that resulted in deprecation warnings in Ruby 2.7 will now result in
ArgumentErroror 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]
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}]], {}]
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Arguments forwarding (
...) now supports leading arguments. [Feature #16378]def method_missing(meth, ...) send(:"do_#{meth}", ...) end
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Pattern matching (
case/in) is no longer experimental. [Feature #17260] -
One-line pattern matching is redesigned. [EXPERIMENTAL]
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=>is added. It can be used like a rightward assignment. [Feature #17260]0 => a p a #=> 0 {b: 0, c: 1} => {b:} p b #=> 0
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inis changed to returntrueorfalse. [Feature #17371]# version 3.0 0 in 1 #=> false # version 2.7 0 in 1 #=> raise NoMatchingPatternError
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Find-pattern is added. [EXPERIMENTAL] [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
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Endless method definition is added. [EXPERIMENTAL] [Feature #16746]
def square(x) = x * x
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Interpolated
Stringliterals are no longer frozen when# frozen-string-literal: trueis used. [Feature #17104] -
Magic comment
shareable_constant_valueadded to freeze constants. See Magic Comments for more details. [Feature #17273] -
A static analysis foundation is introduced.
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Deprecation warnings are no longer shown by default (since Ruby 2.7.2). Turn them on with
-W:deprecated(or with-wto show other warnings too). [Feature #16345] -
$SAFEand$KCODEare now normal global variables with no special behavior. C-API methods related to$SAFEhave been removed. [Feature #16131] [Feature #17136] -
yield in singleton class definitions in methods is now a
SyntaxErrorinstead of a warning. yield in a class definition outside of a method is now aSyntaxErrorinstead of aLocalJumpError. [Feature #15575] -
When a class variable is overtaken by the same definition in an ancestor class/module, a
RuntimeErroris now raised (previously, it only issued a warning in verbose mode). Additionally, accessing a class variable from the toplevel scope is now aRuntimeError. [Bug #14541] -
Assigning to a numbered parameter is now a
SyntaxErrorinstead of a warning.
Command line options¶ ↑
--help option¶ ↑
When the environment variable RUBY_PAGER or PAGER is present and has a non-empty value, and the standard input and output are tty, the --help option shows the help message via the pager designated by the value. [Feature #16754]
--backtrace-limit option¶ ↑
The --backtrace-limit option limits the maximum length of a backtrace. [Feature #8661]
Core classes updates¶ ↑
Outstanding ones only.
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The following methods now return
Arrayinstances instead of subclass instances when called on subclass instances: [Bug #6087] -
Can be sliced with
Enumerator::ArithmeticSequencedirty_data = ['--', 'data1', '--', 'data2', '--', 'data3'] dirty_data[(1..).step(2)] # take each second element # => ["data1", "data2", "data3"]
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Binding#evalwhen called with one argument will use"(eval)"for__FILE__and1for__LINE__in the evaluated code. [Bug #4352] [Bug #17419]
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ConditionVariable
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ConditionVariable#wait may now invoke the
block/unblockscheduler hooks in a non-blocking context. [Feature #16786]
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Dir.globandDir.[]now sort the results by default, and accept thesort:keyword option. [Feature #8709]
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ENV.excepthas been added, which returns a hash excluding the given keys and their values. [Feature #15822] -
Windows: Read
ENVnames and values as UTF-8 encoded Strings [Feature #12650]
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Added new encoding IBM720. [Feature #16233]
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Changed default for
Encoding.default_externalto UTF-8 on Windows [Feature #16604]
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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#backtraceandFiber#backtrace_locationsprovide per-fiber backtrace. [Feature #16815] -
The limitation of
Fiber#transferis relaxed. [Bug #17221]
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GC.auto_compact=andGC.auto_compacthave been added to control when compaction runs. Settingauto_compact=totruewill cause compaction to occur during major collections. At the moment, compaction adds significant overhead to major collections, so please test first! [Feature #17176]
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Hash#transform_keysandHash#transform_keys!now accept a hash that maps keys to new keys. [Feature #16274] -
Hash#excepthas been added, which returns a hash excluding the given keys and their values. [Feature #15822]
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IO#nonblock?now defaults totrue. [Feature #16786] -
IO#wait_readable,IO#wait_writable,IO#read,IO#writeand other related methods (e.g.IO#puts,IO#gets) may invoke the scheduler hook#io_wait(io, events, timeout)in a non-blocking execution context. [Feature #16786]
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Kernel#clonewhen called with thefreeze: falsekeyword will call#initialize_clonewith thefreeze: falsekeyword. [Bug #14266] -
Kernel#clonewhen called with thefreeze: truekeyword will call#initialize_clonewith thefreeze: truekeyword, and will return a frozen copy even if the receiver is unfrozen. [Feature #16175] -
Kernel#evalwhen called with two arguments will use"(eval)"for__FILE__and1for__LINE__in the evaluated code. [Bug #4352] -
Kernel#lambdanow warns if called without a literal block. [Feature #15973] -
Kernel.sleepinvokes the scheduler hook#kernel_sleep(...)in a non-blocking execution context. [Feature #16786]
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Module#includeandModule#prependnow 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]
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Module#public,Module#protected,Module#private,Module#public_class_method,Module#private_class_method, toplevel “private” and “public” methods now accept single array argument with a list of method names. [Feature #17314] -
Module#attr_accessor,Module#attr_reader,Module#attr_writerandModule#attrmethods now return an array of defined method names as symbols. [Feature #17314] -
Module#alias_methodnow returns the defined alias as a symbol. [Feature #17314]
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Mutex
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Mutexis now acquired per-Fiberinstead of per-Thread. This change should be compatible for essentially all usages and avoids blocking when using a scheduler. [Feature #16792]
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Proc#==andProc#eql?are now defined and will return true for separateProcinstances if the procs were created from the same block. [Feature #14267]
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Queue / SizedQueue
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Queue#pop, SizedQueue#push and related methods may now invoke the
block/unblockscheduler hooks in a non-blocking context. [Feature #16786]
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New class added to enable parallel execution. See ractor.md for more details.
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Random::DEFAULTnow refers to theRandomclass instead of being aRandominstance, so it can work withRactor. [Feature #17322] -
Random::DEFAULTis deprecated since its value is now confusing and it is no longer global, useKernel.rand/Random.randdirectly, or create aRandominstance withRandom.newinstead. [Feature #17351]
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The following methods now return or yield
Stringinstances instead of subclass instances when called on subclass instances: [Bug #10845]
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Symbol#to_procnow returns a lambdaProc. [Feature #16260] -
Symbol#namehas been added, which returns the name of the symbol if it is named. The returned string is frozen. [Feature #16150]
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Introduce
Fiber.set_schedulerfor intercepting blocking operations andFiber.schedulerfor accessing the current scheduler. See fiber.md for more details about what operations are supported and how to implement the scheduler hooks. [Feature #16786] -
Fiber.blocking?tells whether the current execution context is blocking. [Feature #16786] -
Thread#joininvokes the scheduler hooksblock/unblockin a non-blocking execution context. [Feature #16786]
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Thread.ignore_deadlockaccessor has been added for disabling the default deadlock detection, allowing the use of signal handlers to break deadlock. [Bug #13768]
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Warning#warnnow supports a category keyword argument. [Feature #17122]
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Stdlib updates¶ ↑
Outstanding ones only.
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Update to
BigDecimal3.0.0 -
This version is
Ractorcompatible.
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Update to
Bundler2.2.3
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Update to 0.2.0
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This version is
Ractorcompatible.
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Update to
CSV3.1.9
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Update to
Fiddle1.0.5
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Update to
IRB1.2.6
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Add :connect_timeout to
TCPSocket.new[Feature #17187]
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Net::HTTP#verify_hostname=andNet::HTTP#verify_hostnamehave been added to skip hostname verification. [Feature #16555] -
Net::HTTP.get,Net::HTTP.get_response, andNet::HTTP.get_printcan take the request headers as aHashin the second argument when the first argument is aURI. [Feature #16686]
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Net::SMTP
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Add SNI support.
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Net::SMTP.start arguments are keyword arguments.
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TLS should not check the host name by default.
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Initialization is no longer lazy. [Bug #12136]
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Builtin methods can now be overridden safely. [Bug #15409]
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Implementation uses only methods ending with
!. -
Ractorcompatible. -
Use officially discouraged. Read Caveats at
OpenStructsection.
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Ractorcompatible.
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Update to
Reline0.1.5
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RubyGems
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Update to RubyGems 3.2.3
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Update to
StringScanner3.0.0 -
This version is
Ractorcompatible.
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URI.escape and URI.unescape have been removed. Instead, use the following methods depending on your specific use case.
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Compatibility issues¶ ↑
Excluding feature bug fixes.
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Regexpliterals and allRangeobjects are frozen. [Feature #8948] [Feature #16377] [Feature #15504]/foo/.frozen? #=> true (42...).frozen? # => true
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EXPERIMENTAL:
Hash#eachconsistently yields a 2-element array. [Bug #12706]-
Now
{ a: 1 }.each(&->(k, v) { })raises anArgumentErrordue to lambda's arity check.
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When writing to STDOUT redirected to a closed pipe, no broken pipe error message will be shown now. [Feature #14413]
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TRUE/FALSE/NILconstants are no longer defined. -
Integer#zero?overridesNumeric#zero?for optimization. [Misc #16961] -
Enumerable#grepandEnumerable#grep_vwhen passed aRegexpand no block no longer modifyRegexp.last_match. [Bug #17030] -
Requiring 'open-uri' no longer redefines
Kernel#open. CallURI.opendirectly oruse URI#openinstead. [Misc #15893] -
SortedSet has been removed for dependency and performance reasons.
Stdlib compatibility issues¶ ↑
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Default gems
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The following libraries are promoted to default gems from stdlib.
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abbrev
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base64
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drb
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debug
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erb
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find
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net-ftp
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net-http
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net-imap
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net-protocol
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open-uri
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optparse
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pp
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prettyprint
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resolv-replace
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resolv
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rinda
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set
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securerandom
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shellwords
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tempfile
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tmpdir
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time
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tsort
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un
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weakref
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The following extensions are promoted to default gems from stdlib.
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digest
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io-nonblock
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io-wait
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nkf
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pathname
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syslog
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win32ole
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Bundled gems
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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.
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SDBM has been removed from the Ruby standard library. [Bug #8446]
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The issues of sdbm will be handled at github.com/ruby/sdbm
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WEBrick has been removed from the Ruby standard library. [Feature #17303]
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The issues of WEBrick will be handled at github.com/ruby/webrick
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C API updates¶ ↑
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C API functions related to
$SAFEhave been removed. [Feature #16131] -
C API header file
ruby/ruby.hwas split. [GH-2991]This should have no impact on extension libraries, but users might experience slow compilations.
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Memory view interface [EXPERIMENTAL]
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The memory view interface is a C-API set to exchange a raw memory area, such as a numeric array or 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]
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Ractorrelated C APIs are introduced (experimental) in “include/ruby/ractor.h”.
Implementation improvements¶ ↑
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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 mechanisms, (1) Disposable inline method cache (2) per-Class method cache and (3) new invalidation mechanism. (1) can avoid per-method call synchronization because it only uses atomic operations. See the ticket for more details.
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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.
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superis optimized when the same type of method is called in the previous call if it’s not refinements or an attr reader or writer.
JIT¶ ↑
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Performance improvements of JIT-ed code
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Microarchitectural optimizations
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Native functions shared by multiple methods are deduplicated on JIT compaction.
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Decrease code size of hot paths by some optimizations and partitioning cold paths.
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Instance variables
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Eliminate some redundant checks.
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Skip checking a class and a object multiple times in a method when possible.
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Optimize accesses in some core classes like
Hashand their subclasses.
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Methodinlining support for some C methods-
Kernel:#class,#frozen? -
Integer:#-@,#~,#abs,#bit_length,#even?,#integer?,#magnitude,#odd?,#ord,#to_i,#to_int,#zero? -
Struct: reader methods for 10th or later members
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Constant references are inlined.
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Always generate appropriate code for
==,nil?, and!calls depending on a receiver class. -
Reduce the number of PC accesses on branches and method returns.
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Optimize C method calls a little.
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Compilation process improvements
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It does not keep temporary files in /tmp anymore.
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Throttle
GCand compaction of JIT-ed code. -
Avoid GC-ing JIT-ed code when not necessary.
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GC-ing JIT-ed code is executed in a background thread.
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Reduce the number of locks between Ruby and JIT threads.
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Static analysis¶ ↑
RBS¶ ↑
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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.
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Ruby ships with type definitions for core/stdlib classes.
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rbsgem is bundled to load and process RBS files.
TypeProf¶ ↑
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TypeProf is a type analysis tool for Ruby code based on abstract interpretation.
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It reads non-annotated Ruby code, tries inferring its type signature, and prints the analysis result in RBS format.
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Though it supports only a subset of the Ruby language yet, we will continuously improve the coverage of language features, analysis performance, and usability.
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# test.rb def foo(x) if x > 10 x.to_s else nil end end foo(42)
$ typeprof test.rb # Classes class Object def foo : (Integer) -> String? end
Miscellaneous changes¶ ↑
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Methods using
ruby2_keywordswill no longer keep empty keyword splats, those are now removed just as they are for methods not usingruby2_keywords. -
When an exception is caught in the default handler, the error message and backtrace are printed in order from the innermost. [Feature #8661]
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Accessing an uninitialized instance variable no longer emits a warning in verbose mode. [Feature #17055]