NEWS for Ruby 2.6.0¶ ↑

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 2.5.0 release¶ ↑

Language changes¶ ↑

• $SAFE now is a process global state and can be set to 0 again. [Feature #14250]

• Refinements take place at block passing. [Feature #14223]

• Refinements take place at Kernel#public_send. [Feature #15326]

• Refinements take place at Kernel#respond_to?. [Feature #15327]

• else without rescue now causes a syntax error. [EXPERIMENTAL] [Feature #14606]

• Constant names may start with a non-ASCII capital letter. [Feature #13770]

• Endless ranges are introduced. You can use a Range that has no end, like (0..) (or similarly (0...)). [Feature #12912]

  The following shows typical use cases:

  ary[1..]                              # identical to ary[1..-1]
  (1...).each {|index| block }          # infinite loop from index 1
  ary.zip(1..) {|elem, index| block }   # ary.each.with_index(1) { }
  

• Non-Symbol keys in a keyword arguments hash cause an exception.

• The “shadowing outer local variable” warning is removed. [Feature #12490]

  You can now write the following without warning:

  user = users.find {|user| cond(user) }
  

• Print cause of the exception if the exception is not caught and printed its backtraces and error message. [Feature #8257]

• The flip-flop syntax is deprecated. [Feature #5400]

Core classes updates (outstanding ones only)¶ ↑

Array

New methods

• Added Array#union and Array#difference instance methods. [Feature #14097]

Modified method

• Array#to_h now accepts a block that maps elements to new key/value pairs. [Feature #15143]

Aliased methods

• Array#filter is a new alias for Array#select. [Feature #13784]

• Array#filter! is a new alias for Array#select!. [Feature #13784]

Binding

New method

• Added Binding#source_location. [Feature #14230]

  This method returns the source location of the binding, a 2-element array of __FILE__ and __LINE__. Traditionally, the same information could be retrieved by eval("[__FILE__, __LINE__]", binding), but we are planning to change this behavior so that Kernel#eval ignores binding’s source location [Bug #4352]. So, users should use this newly-introduced method instead of Kernel#eval.

Dir

New methods

• Added Dir#each_child and Dir#children instance methods. [Feature #13969]

Enumerable

New method

• Enumerable#chain returns an enumerator object that iterates over the elements of the receiver and then those of each argument in sequence. [Feature #15144]

Modified method

• Enumerable#to_h now accepts a block that maps elements to new key/value pairs. [Feature #15143]

Aliased method

• Enumerable#filter is a new alias for Enumerable#select. [Feature #13784]

Enumerator::ArithmeticSequence

• This is a new class to represent a generator of an arithmetic sequence, that is a number sequence defined by a common difference. It can be used for representing what is similar to Python’s slice. You can get an instance of this class from Numeric#step and Range#step.

Enumerator::Chain

• This is a new class to represent a chain of enumerables that works as a single enumerator, generated by such methods as Enumerable#chain and Enumerator#+.

Enumerator::Lazy

Aliased method

• Enumerator::Lazy#filter is a new alias for Enumerator::Lazy#select. [Feature #13784]

Enumerator

New methods

• Enumerator#+ returns an enumerator object that iterates over the elements of the receiver and then those of the other operand. [Feature #15144]

ENV

Modified method

• ENV.to_h now accepts a block that maps names and values to new keys and values. [Feature #15143]

Exception

New options

• Exception#full_message takes :highlight and :order options. [Bug #14324]

Hash

Modified methods

• Hash#merge, Hash#merge!, and Hash#update now accept multiple arguments. [Feature #15111]

• Hash#to_h now accepts a block that maps keys and values to new keys and values. [Feature #15143]

Aliased methods

• Hash#filter is a new alias for Hash#select. [Feature #13784]

• Hash#filter! is a new alias for Hash#select!. [Feature #13784]

IO

New option

• Added new mode character 'x' to open files for exclusive access. [Feature #11258]

Kernel

Aliased method

• Kernel#then is a new alias for Kernel#yield_self. [Feature #14594]

New options

• Kernel#Complex, Kernel#Float, Kernel#Integer, and Kernel#Rational take an :exception option to specify the way of error handling. [Feature #12732]

• Kernel#system takes an :exception option to raise an exception on failure. [Feature #14386]

Incompatible changes

• Kernel#system and Kernel#exec do not close non-standard file descriptors (the default of the :close_others option is changed to false, but we still set the FD_CLOEXEC flag on descriptors we create). [Misc #14907]

KeyError

New options

• KeyError.new accepts :receiver and :key options to set receiver and key in Ruby code. [Feature #14313]

Method

New methods

• Added Method#<< and Method#>> for Proc composition. [Feature #6284]

Module

Modified methods

• Module#method_defined?, Module#private_method_defined?, and Module#protected_method_defined? now accept the second parameter as optional. If it is true (the default value), it checks ancestor modules/classes, or checks only the class itself. [Feature #14944]

NameError

New option

• NameError.new accepts a :receiver option to set receiver in Ruby code. [Feature #14313]

NilClass

New method

• NilClass#=~ is added for compatibility. [Feature #15231]

NoMethodError

New option

• NoMethodError.new accepts a :receiver option to set receiver in Ruby code. [Feature #14313]

Numeric

Incompatible changes

• Numeric#step now returns an instance of the Enumerator::ArithmeticSequence class rather than one of the Enumerator class.

OpenStruct

Modified method

• OpenStruct#to_h now accepts a block that maps keys and values to new keys and values. [Feature #15143]

Proc

New methods

• Added Proc#<< and Proc#>> for Proc composition. [Feature #6284]

Incompatible changes

• Proc#call doesn’t change $SAFE any more. [Feature #14250]

Random

New method

• Added Random.bytes. [Feature #4938]

Range

New method

• Added Range#% instance method. [Feature #14697]

Incompatible changes

• Range#=== now uses the cover? instead of the include? method. [Feature #14575]

• Range#cover? now accepts a Range object. [Feature #14473]

• Range#step now returns an instance of the Enumerator::ArithmeticSequence class rather than one of the Enumerator class.

Regexp/String

• Update Unicode version from 10.0.0 to 11.0.0. [Feature #14802]

  This includes a rewrite of the grapheme cluster (/X/) algorithm and special-casing for Georgian MTAVRULI on String#downcase.

• Update Emoji version from 5.0 to 11.0.0 [Feature #14802]

RubyVM::AbstractSyntaxTree

New methods

• RubyVM::AbstractSyntaxTree.parse parses a given string and returns AST nodes. [experimental]

• RubyVM::AbstractSyntaxTree.parse_file parses a given file and returns AST nodes. [experimental]

• RubyVM::AbstractSyntaxTree.of returns AST nodes of the given proc or method. [experimental]

RubyVM

New method

• RubyVM.resolve_feature_path identifies the file that will be loaded by “require(feature)”. [experimental] [Feature #15230]

String

• String#crypt is now deprecated. [Feature #14915]

New features

• String#split yields each substring to the block if given. [Feature #4780]

Struct

Modified method

• Struct#to_h now accepts a block that maps keys and values to new keys and values. [Feature #15143]

Aliased method

• Struct#filter is a new alias for Struct#select. [Feature #13784]

Time

New features

• Time.new and Time#getlocal accept a timezone object as well as a UTC offset string. Time#+, Time#-, and Time#succ also preserve the timezone. [Feature #14850]

TracePoint

New features

• “script_compiled” event is supported. [Feature #15287]

New methods

• TracePoint#parameters [Feature #14694]

• TracePoint#instruction_sequence [Feature #15287]

• TracePoint#eval_script [Feature #15287]

Modified method

• TracePoint#enable accepts new keywords “target:” and “target_line:”. [Feature #15289]

Stdlib updates (outstanding ones only)¶ ↑

BigDecimal

Update to version 1.4.0. This version includes several compatibility issues, see Compatibility issues section below for details.

Modified method

• BigDecimal() accepts the new keyword “exception:” similar to Float().

Note for the differences among recent versions

You should want to know the differences among recent versions of bigdecimal. Please select the suitable version of bigdecimal according to the following information.

• 1.3.5 has BigDecimal.new without “exception:” keyword. You can see the deprecation warning of BigDecimal.new when you specify “-w” option. BigDecimal(), BigDecimal.new, and Object#to_d methods are the same.

• 1.4.0 has BigDecimal.new with “exception:” keyword. You always see the deprecation warning of BigDecimal.new. Object#to_d method is different from BigDecimal() and BigDecimal.new.

• 2.0.0 will be released soon after releasing Ruby 2.6.0. This version will not have the BigDecimal.new method.

Bundler

• Add Bundler to Standard Library. [Feature #12733]

• Use 1.17.2, the latest stable version.

Coverage

A oneshot_lines mode is added. [Feature #15022]

This mode checks “whether each line was executed at least once or not”, instead of “how many times each line was executed”. A hook for each line is fired at most once, and after it is fired the hook flag is removed, i.e., it runs with zero overhead.

New options

• Add :oneshot_lines keyword argument to Coverage.start.

• Add :stop and :clear keyword arguments to Coverage.result. If clear is true, it clears the counters to zero. If stop is true, it disables coverage measurement.

New methods

• Coverage.line_stub, which is a simple helper function that creates the “stub” of line coverage from a given source code.

CSV

• Upgrade to 3.0.2. This includes performance improvements especially for writing. Writing is about 2 times faster. See github.com/ruby/csv/blob/master/NEWS.md.

ERB

New options

• Add :trim_mode and :eoutvar keyword arguments to ERB.new. Now non-keyword arguments other than the first one are softly deprecated and will be removed when Ruby 2.5 becomes EOL. [Feature #14256]

• erb command’s -S option is deprecated, and will be removed in the next version.

FileUtils

New methods

• FileUtils#cp_lr. [Feature #4189]

Matrix

New methods

• Matrix#antisymmetric?, Matrix#skew_symmetric?

• Matrix#map!, Matrix#collect! [Feature #14151]

• Matrix#[]=

• Vector#map!, Vector#collect!

• Vector#[]=

Net

New options

• Add :write_timeout keyword argument to Net::HTTP.new. [Feature #13396]

New methods

• Add Net::HTTP#write_timeout and Net::HTTP#write_timeout=. [Feature #13396]

New constant

• Add Net::HTTPClientException to deprecate Net::HTTPServerException, whose name is misleading. [Bug #14688]

NKF

• Upgrade to nkf v2.1.5

Psych

• Upgrade to Psych 3.1.0

RDoc

• Become about 2 times faster.

• Use SOURCE_DATE_EPOCH to generate files.

• Fix method line number that slipped off.

• Enable --width, --exclude, and --line-numbers that were ignored.

• Add support for blockquote by “>>>” in default markup notation.

• Add support for “Raises” lines in TomDoc notation.

• Fix syntax error output.

• Fix many parsing bugs.

REXML

• Upgrade to REXML 3.1.9. See github.com/ruby/rexml/blob/master/NEWS.md.

Improved some XPath implementations

• concat() function: Stringify all arguments before concatenating.

• string() function: Support context node.

• string() function: Support processing instruction node.

• Support "*:#{ELEMENT_NAME}" syntax in XPath 2.0.

Fixed some XPath implementations

• "//#{ELEMENT_NAME}[#{POSITION}]" case

• string() function: Fix function(document) returns nodes that are out of root elements.

• "/ #{ELEMENT_NAME} " case

• "/ #{ELEMENT_NAME} [ #{PREDICATE} ]" case

• "/ #{AXIS}::#{ELEMENT_NAME}" case

• "#{N}-#{M}" case: One or more white spaces were required before "-"

• "/child::node()" case

• "#{FUNCTION}()/#{PATH}" case

• "@#{ATTRIBUTE}/parent::" case

• "name(#{NODE_SET})" case

RSS

New options

• RSS::Parser.parse now accepts options as Hash. :validate , :ignore_unknown_element , :parser_class options are available.

RubyGems

• Upgrade to RubyGems 3.0.1

• blog.rubygems.org/2018/12/19/3.0.0-released.html

• blog.rubygems.org/2018/12/23/3.0.1-released.html

Set

Aliased method

• Set#filter! is a new alias for Set#select!. [Feature #13784]

URI

New constant

• Add URI::File to handle the file URI scheme. [Feature #14035]

Compatibility issues (excluding feature bug fixes)¶ ↑

Dir

• Dir.glob with '\0'-separated pattern list will be deprecated, and is now warned. [Feature #14643]

File

• File.read, File.binread, File.write, File.binwrite, File.foreach, and File.readlines do not invoke external commands even if the path starts with the pipe character '|'. [Feature #14245]

Object

• Object#=~ is deprecated. [Feature #15231]

Stdlib compatibility issues (excluding feature bug fixes)¶ ↑

• These standard libraries have been promoted to default gems.

  • e2mmap

  • forwardable

  • irb

  • logger

  • matrix

  • mutex_m

  • ostruct

  • prime

  • rexml

  • rss

  • shell

  • sync

  • thwait

  • tracer

BigDecimal

• The following methods are removed.

  • BigDecimal.allocate

  • BigDecimal.ver

• Every BigDecimal object is frozen. [Feature #13984]

• BigDecimal() parses the given string similar to Float().

• String#to_d parses the receiver string similar to String#to_f.

• BigDecimal.new will be removed in version 2.0.

Pathname

• Pathname#read, Pathname#binread, Pathname#write, Pathname#binwrite, Pathname#each_line and Pathname#readlines do not invoke external commands even if the path starts with the pipe character '|'. This follows [Feature #14245].

Implementation improvements¶ ↑

• Speedup Proc#call because we don’t need to care about $SAFE any more. [Feature #14318]

  With lc_fizzbuzz benchmark which uses Proc#call many times we can measure x1.4 improvements. [Bug #10212]

• Speedup block.call where block is passed block parameter. [Feature #14330]

  Ruby 2.5 improves block passing performance. [Feature #14045]

  Additionally, Ruby 2.6 improves the performance of passed block calling.

• Introduce an initial implementation of a JIT (Just-in-time) compiler. [Feature #14235] [experimental]

  • --jit command line option is added to enable JIT. --jit-verbose=1 is good for inspection. See ruby --help for others.

  • To generate machine code, this JIT compiler uses the C compiler used for building the interpreter. Currently GCC, Clang, and Microsoft Visual C++ are supported for it.

  • --disable-mjit-support option is added to configure. This is added for JIT debugging, but if you get an error on building a header file for JIT, you can use this option to skip building it as a workaround.

  • rb_waitpid reimplemented on Unix-like platforms to maintain compatibility with processes created for JIT [Bug #14867]

• VM generator script renewal; makes the generated VM more optimized. [GH-1779]

• Thread cache enabled for pthreads platforms (for Thread.new and Thread.start). [Feature #14757]

• timer thread is eliminated for platforms with POSIX timers. [Misc #14937]

• Transient Heap (theap) is supported. [Bug #14858] [Feature #14989]

  theap is a managed heap for short-living memory objects. For example, making a small and short-living Hash object is x2 faster. With rdoc benchmark, we measured 6-7% performance improvement.

• Native implementations (arm32, arm64, ppc64le, win32, win64, x86, amd64) of coroutines to improve performance of Fiber significantly. [Feature #14739]

Miscellaneous changes¶ ↑

• On macOS, shared libraries no longer include a full version number of Ruby in their names. This eliminates the burden of each teeny upgrade on the platform that users need to rebuild every extension library.

  Before

  • libruby.2.6.0.dylib

  • libruby.2.6.dylib -> libruby.2.6.0.dylib

  • libruby.dylib -> libruby.2.6.0.dylib

  After

  • libruby.2.6.dylib

  • libruby.dylib -> libruby.2.6.dylib

• Extracted misc/*.el files to github.com/ruby/elisp