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
Modified method

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

Aliased methods
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
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
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
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
Hash
Modified methods
Aliased methods
IO
New option

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

Kernel
Aliased method
New options
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
Module
Modified methods
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
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
Incompatible changes

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

Random
New method
Range
New method

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

Incompatible changes
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
New method

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

String
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
Time
New features
TracePoint
New features

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

New methods
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
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
New constant
NKF

  • Upgrade to nkf v2.1.5

Psych
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
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
Set
Aliased method
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
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

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