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¶ ↑
-
Pattern matching is introduced as an experimental feature. [Feature #14912]
case [0, [1, 2, 3]] in [a, [b, *c]] p a #=> 0 p b #=> 1 p c #=> [2, 3] end case {a: 0, b: 1} in {a: 0, x: 1} :unreachable in {a: 0, b: var} p var #=> 1 end case -1 in 0 then :unreachable in 1 then :unreachable end #=> NoMatchingPatternError json = <<END { "name": "Alice", "age": 30, "children": [{ "name": "Bob", "age": 2 }] } END JSON.parse(json, symbolize_names: true) in {name: "Alice", children: [{name: name, age: age}]} p name #=> "Bob" p age #=> 2 JSON.parse(json, symbolize_names: true) in {name: "Alice", children: [{name: "Charlie", age: age}]} #=> NoMatchingPatternError
-
See the following slides for more details:
-
speakerdeck.com/k_tsj/pattern-matching-new-feature-in-ruby-2-dot-7
-
Note that the slides are slightly obsolete.
-
-
The warning against pattern matching can be suppressed with -W:no-experimental option.
The spec of keyword arguments is changed towards 3.0¶ ↑
-
Automatic conversion of keyword arguments and positional arguments is deprecated, and conversion will be removed in Ruby 3. [Feature #14183]
-
When a method call passes a
Hash
at the last argument, and when it passes no keywords, and when the called method accepts keywords, a warning is emitted. To continue treating the hash as keywords, add a double splat operator to avoid the warning and ensure correct behavior in Ruby 3.def foo(key: 42); end; foo({key: 42}) # warned def foo(**kw); end; foo({key: 42}) # warned def foo(key: 42); end; foo(**{key: 42}) # OK def foo(**kw); end; foo(**{key: 42}) # OK
-
When a method call passes keywords to a method that accepts keywords, but it does not pass enough required positional arguments, the keywords are treated as a final required positional argument, and a warning is emitted. Pass the argument as a hash instead of keywords to avoid the warning and ensure correct behavior in Ruby 3.
def foo(h, **kw); end; foo(key: 42) # warned def foo(h, key: 42); end; foo(key: 42) # warned def foo(h, **kw); end; foo({key: 42}) # OK def foo(h, key: 42); end; foo({key: 42}) # OK
-
When a method accepts specific keywords but not a keyword splat, and a hash or keywords splat is passed to the method that includes both
Symbol
and non-Symbol keys, the hash will continue to be split, and a warning will be emitted. You will need to update the calling code to pass separate hashes to ensure correct behavior in Ruby 3.def foo(h={}, key: 42); end; foo("key" => 43, key: 42) # warned def foo(h={}, key: 42); end; foo({"key" => 43, key: 42}) # warned def foo(h={}, key: 42); end; foo({"key" => 43}, key: 42) # OK
-
If a method does not accept keywords, and is called with keywords, the keywords are still treated as a positional hash, with no warning. This behavior will continue to work in Ruby 3.
def foo(opt={}); end; foo( key: 42 ) # OK
-
-
Non-symbols are allowed as keyword argument keys if the method accepts arbitrary keywords. [Feature #14183]
-
Non-Symbol keys in a keyword arguments hash were prohibited in 2.6.0, but are now allowed again. [Bug #15658]
def foo(**kw); p kw; end; foo("str" => 1) #=> {"str"=>1}
-
-
**nil
is allowed in method definitions to explicitly mark that the method accepts no keywords. Calling such a method with keywords will result in anArgumentError
. [Feature #14183]def foo(h, **nil); end; foo(key: 1) # ArgumentError def foo(h, **nil); end; foo(**{key: 1}) # ArgumentError def foo(h, **nil); end; foo("str" => 1) # ArgumentError def foo(h, **nil); end; foo({key: 1}) # OK def foo(h, **nil); end; foo({"str" => 1}) # OK
-
Passing an empty keyword splat to a method that does not accept keywords no longer passes an empty hash, unless the empty hash is necessary for a required parameter, in which case a warning will be emitted. Remove the double splat to continue passing a positional hash. [Feature #14183]
h = {}; def foo(*a) a end; foo(**h) # [] h = {}; def foo(a) a end; foo(**h) # {} and warning h = {}; def foo(*a) a end; foo(h) # [{}] h = {}; def foo(a) a end; foo(h) # {}
-
Above warnings can be suppressed also with -W:no-deprecated option.
Numbered parameters¶ ↑
-
Numbered parameters as default block parameters are introduced. [Feature #4475]
[1, 2, 10].map { _1.to_s(16) } #=> ["1", "2", "a"] [[1, 2], [3, 4]].map { _1 + _2 } #=> [3, 7]
You can still define a local variable named
_1
and so on, and that is honored when present, but renders a warning._1 = 0 #=> warning: `_1' is reserved for numbered parameter; consider another name [1].each { p _1 } # prints 0 instead of 1
proc/lambda without block is deprecated¶ ↑
-
Proc.new
andKernel#proc
with no block in a method called with a block will now display a warning.def foo proc end foo { puts "Hello" } #=> warning: Capturing the given block using Kernel#proc is deprecated; use `&block` instead
This warning can be suppressed with -W:no-deprecated option.
-
Kernel#lambda
with no block in a method called with a block raises an exception.def bar lambda end bar { puts "Hello" } #=> tried to create Proc object without a block (ArgumentError)
Other miscellaneous changes¶ ↑
-
A beginless range is experimentally introduced. It might be useful in
case
, new call-sequence of theComparable#clamp
, constants and DSLs. [Feature #14799]ary[..3] # identical to ary[0..3] case RUBY_VERSION when ..."2.4" then puts "EOL" # ... end age.clamp(..100) where(sales: ..100)
-
Setting
$;
to a non-nil value will now display a warning. [Feature #14240] This includes the usage inString#split
. This warning can be suppressed with -W:no-deprecated option. -
Setting
$,
to a non-nil value will now display a warning. [Feature #14240] This includes the usage inArray#join
. This warning can be suppressed with -W:no-deprecated option. -
Quoted here-document identifiers must end within the same line.
<<"EOS " # This had been warned since 2.4; Now it raises a SyntaxError EOS
-
The flip-flop syntax deprecation is reverted. [Feature #5400]
-
Comment lines can be placed between fluent dot now.
foo # .bar .baz # => foo.baz
-
Calling a private method with a literal
self
as the receiver is now allowed. [Feature #11297] [Feature #16123] -
Modifier rescue now operates the same for multiple assignment as single assignment. [Bug #8279]
a, b = raise rescue [1, 2] # Previously parsed as: (a, b = raise) rescue [1, 2] # Now parsed as: a, b = (raise rescue [1, 2])
-
yield
in singleton class syntax will now display a warning. This behavior will soon be deprecated. [Feature #15575].def foo class << Object.new yield #=> warning: `yield' in class syntax will not be supported from Ruby 3.0. [Feature #15575] end end foo { p :ok }
This warning can be suppressed with -W:no-deprecated option.
-
Argument forwarding by
(...)
is introduced. [Feature #16253]def foo(...) bar(...) end
All arguments to
foo
are forwarded tobar
, including keyword and block arguments. Note that the parentheses are mandatory.bar ...
is parsed as an endless range. -
Access and setting of
$SAFE
will now always display a warning.$SAFE
will become a normal global variable in Ruby 3.0. [Feature #16131] -
Object#{taint,untaint,trust,untrust}
and related functions in the C-API no longer have an effect (all objects are always considered untainted), and will now display a warning in verbose mode. This warning will be disabled even in non-verbose mode in Ruby 3.0, and the methods and C functions will be removed in Ruby 3.2. [Feature #16131] -
Refinements take place at
Object#method
andModule#instance_method
. [Feature #15373]
Command line options¶ ↑
Warning
option¶ ↑
The -W
option has been extended with a following :
, to manage categorized warnings. [Feature #16345] [Feature #16420]
-
To suppress deprecation warnings:
$ ruby -e '$; = ""' -e:1: warning: `$;' is deprecated $ ruby -W:no-deprecated -e '$; = //'
-
It works with the
RUBYOPT
environment variable:$ RUBYOPT=-W:no-deprecated ruby -e '$; = //'
-
To suppress experimental feature warnings:
$ ruby -e '0 in a' -e:1: warning: Pattern matching is experimental, and the behavior may change in future versions of Ruby! $ ruby -W:no-experimental -e '0 in a'
-
To suppress both by using
RUBYOPT
, set space separated values:$ RUBYOPT='-W:no-deprecated -W:no-experimental' ruby -e '($; = "") in a'
See also Warning
in Core classes updates.
Core classes updates (outstanding ones only)¶ ↑
Array
- New methods
-
Added
Array#intersection
. [Feature #16155] -
Added
Array#minmax
, with a faster implementation thanEnumerable#minmax
. [Bug #15929]
-
Comparable
- Modified method
-
Comparable#clamp
now accepts aRange
argument. [Feature #14784]-1.clamp(0..2) #=> 0 1.clamp(0..2) #=> 1 3.clamp(0..2) #=> 2 # With beginless and endless ranges: -1.clamp(0..) #=> 0 3.clamp(..2) #=> 2
-
Complex
- New method
-
Added Complex#<=>. So
0 <=> 0i
will not raiseNoMethodError
. [Bug #15857]
-
Dir
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 anEnumerator
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] -
Added
Enumerator::Lazy#with_index
be lazy Previously,Enumerator::Lazy#with_index
was not defined, so it picked up the default implementation fromEnumerator
, which was not lazy. [Bug #7877]("a"..).lazy.with_index(1) { |it, index| puts "#{index}:#{it}" }.take(3).force # => 1:a # 2:b # 3:c
-
Fiber
- New method
-
Added
Fiber#raise
that behaves likeFiber#resume
but raises an exception on the resumed fiber. [Feature #10344]
-
File
- New method
-
Added
File.absolute_path?
to check whether a path is absolute or not in a portable way. [Feature #15868]File.absolute_path?("/foo") # => true (on *nix) File.absolute_path?("C:/foo") # => true (on Windows) File.absolute_path?("foo") # => false
-
- Modified method
-
File.extname
now returns a dot string for names ending with a dot on non-Windows platforms. [Bug #15267]File.extname("foo.") #=> "."
-
FrozenError
- New method
-
Added
FrozenError#receiver
to return the frozen object on which modification was attempted. To set this object when raisingFrozenError
in Ruby code,FrozenError.new
accepts a:receiver
option. [Feature #15751]
-
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 (copy-on-write) friendly. [Feature #15626]Details on the algorithm and caveats can be found here: bugs.ruby-lang.org/issues/15626
-
IO
- New method
-
Added
IO#set_encoding_by_bom
to check the BOM and set the external encoding. [Bug #15210]
-
Integer
- Modified method
-
Integer#[]
now supports range operations. [Feature #8842]0b01001101[2, 4] #=> 0b0011 0b01001100[2..5] #=> 0b0011 0b01001100[2...6] #=> 0b0011 # ^^^^
-
Method
- Modified method
-
Method#inspect
shows more information. [Feature #14145]
-
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
-
Module#autoload?
now takes aninherit
optional argument, likeModule#const_defined?
. [Feature #15777] -
Module#name
now always returns a frozenString
. The returnedString
is always the same for a givenModule
. This change is experimental. [Feature #16150]
-
NilClass
/TrueClass
/FalseClass
- Modified methods
-
NilClass#to_s
,TrueClass#to_s
, andFalseClass#to_s
now always return a frozenString
. The returnedString
is always the same for each of these values. This change is experimental. [Feature #16150]
-
ObjectSpace::WeakMap
- Modified method
-
ObjectSpace::WeakMap#[]=
now accepts special objects as either key or values. [Feature #16035]
-
Proc
- New method
-
Added
Proc#ruby2_keywords
for marking the proc as passing keyword arguments through a regular argument splat, useful when delegating all arguments to another method or proc in a way that can be backwards compatible with older Ruby versions. [Feature #16404]
-
Range
- New method
-
Added
Range#minmax
, with a faster implementation thanEnumerable#minmax
. It returns a maximum that now corresponds toRange#max
. [Bug #15807]
-
- Modified method
-
Range#===
now usesRange#cover?
forString
arguments, too (in Ruby 2.6, it was changed fromRange#include?
for all types except strings). [Bug #15449]
-
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]
-
Symbol
- New methods
-
Added
Symbol#start_with?
andSymbol#end_with?
methods. [Feature #16348]
-
Time
- New methods
-
Added
Time#ceil
method. [Feature #15772] -
Added
Time#floor
method. [Feature #15653]
-
- Modified method
-
Time#inspect
is separated fromTime#to_s
and it shows the time’s sub second. [Feature #15958]
-
UnboundMethod
- New method
-
Added
UnboundMethod#bind_call
method. [Feature #15955]umethod.bind_call(obj, ...)
is semantically equivalent toumethod.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 an intermediateMethod
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
-
Warning
- New methods
-
Added
Warning.[]
andWarning.[]=
to manage emitting/suppressing some categories of warnings. [Feature #16345] [Feature #16420]
-
- $LOAD_PATH
- New method
-
Added
$LOAD_PATH.resolve_feature_path
. [Feature #15903] [Feature #15230]
-
Stdlib updates (outstanding ones only)¶ ↑
- Bundler
-
Upgrade to Bundler 2.1.2. See github.com/bundler/bundler/releases/tag/v2.1.2
-
- CGI
-
CGI.escapeHTML becomes 2~5x faster when there is at least one escaped character. See github.com/ruby/ruby/pull/2226
-
- CSV
-
Upgrade to 3.1.2. See github.com/ruby/csv/blob/master/NEWS.md.
-
- Date
-
Date.jisx0301, Date#jisx0301, and Date.parse support the new Japanese era. [Feature #15742]
-
- Delegator
-
Object#DelegateClass accepts a block and module_evals it in the context of the returned class, similar to
Class.new
andStruct.new
.
-
- ERB
-
Prohibit marshaling ERB instance.
-
- IRB
-
Introduce syntax highlighting inspired by the Pry gem to Binding#irb source lines, REPL input, and inspect output of some core-class objects.
-
Introduce multiline editing mode provided by Reline.
-
Show documentation when completion.
-
Enable auto indent and save/load history by default.
-
- JSON
-
Upgrade to 2.3.0.
-
- Net::FTP
-
Add Net::FTP#features to check available features, and Net::FTP#option to enable/disable each of them. [Feature #15964]
-
- Net::HTTP
-
Add
ipaddr
optional parameter to Net::HTTP#start to replace the address for the TCP/IP connection. [Feature #5180]
-
- 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 options. [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
-
Pathname.glob now delegates 3 arguments to
Dir.glob
to acceptbase
keyword. [Feature #14405]
-
- Racc
-
Merge 1.4.15 from upstream repository and added cli of racc.
-
- Reline
-
New stdlib that is compatible with the readline stdlib but is implemented in pure Ruby. It also provides a multiline editing mode.
-
- REXML
-
Upgrade to 3.2.3. See github.com/ruby/rexml/blob/master/NEWS.md.
-
- RSS
-
Upgrade to RSS 0.2.8. See github.com/ruby/rss/blob/master/NEWS.md.
-
- RubyGems
- StringScanner
-
Upgrade to 1.0.3. See github.com/ruby/strscan/blob/master/NEWS.md.
-
Compatibility issues (excluding feature bug fixes)¶ ↑
-
The following libraries are no longer bundled gems. Install corresponding gems to use these features.
-
CMath (cmath gem)
-
Scanf (scanf gem)
-
Shell (shell gem)
-
Synchronizer (sync gem)
-
ThreadsWait (thwait gem)
-
E2MM (e2mmap gem)
-
Proc
-
The
Proc#to_s
format was changed. [Feature #16101]
-
Range
-
Range#minmax
used to iterate on the range to determine the maximum. It now uses the same algorithm asRange#max
. In rare cases (e.g. ranges of Floats or Strings), this may yield different results. [Bug #15807]
-
Stdlib compatibility issues (excluding feature bug fixes)¶ ↑
-
Promote stdlib to default gems
-
The following default gems were published on rubygems.org
-
benchmark
-
cgi
-
delegate
-
getoptlong
-
net-pop
-
net-smtp
-
open3
-
pstore
-
readline
-
readline-ext
-
singleton
-
-
The following default gems were only promoted at ruby-core, but not yet published on rubygems.org.
-
monitor
-
observer
-
timeout
-
tracer
-
uri
-
yaml
-
-
-
The
did_you_mean
gem has been promoted up to a default gem from a bundled gem
- 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. It was unmaintained since Ruby 2.0.0.
-
C API updates¶ ↑
-
Many
*_kw
functions have been added for setting whether the final argument being passed should be treated as keywords. You may need to switch to these functions to avoid keyword argument separation warnings, and to ensure correct behavior in Ruby 3. -
The
:
character in rb_scan_args format string is now treated as keyword arguments. Passing a positional hash instead of keyword arguments will emit a deprecation warning. -
C API declarations with
ANYARGS
are changed not to useANYARGS
. See github.com/ruby/ruby/pull/2404
Implementation improvements¶ ↑
Fiber
-
Allow selecting different coroutine implementations 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. github.com/ruby/ruby/pull/2224
-
File
-
File.realpath
now uses realpath(3) on many platforms, which can significantly improve performance. [Feature #15797]
-
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. Around 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. -
The default value of
--jit-max-cache
is changed from 1,000 to 100. -
The default value of
--jit-min-calls
is changed from 5 to 10,000.
-
RubyVM
-
Per-call-site method cache, which has been there since around 1.9, was improved: cache hit rate raised from 89% to 94%. See github.com/ruby/ruby/pull/2583
-
RubyVM::InstructionSequence
-
RubyVM::InstructionSequence#to_binary
method generates compiled binary. The binary size is reduced. [Feature #16163]
-
Miscellaneous changes¶ ↑
-
Support for IA64 architecture has been removed. Hardware for testing was difficult to find, native fiber code is difficult to implement, and it added non-trivial complexity to the interpreter. [Feature #15894]
-
Require compilers to support C99. [Misc #15347]
-
Details of our dialect: bugs.ruby-lang.org/projects/ruby-master/wiki/C99
-
-
Ruby’s upstream repository is changed from Subversion to Git.
-
RUBY_DESCRIPTION includes Git revision instead of Subversion’s one.
-
Support built-in methods in Ruby with the
__builtin_
syntax. [Feature #16254]Some methods are defined in *.rb (such as trace_point.rb). For example, it is easy to define a method which accepts keyword arguments.