ruby/NEWS

# -*- rdoc -*-

= 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. <tt>https://bugs.ruby-lang.org/issues/$FEATURE_OR_BUG_NUMBER</tt>)

== Changes since the 2.5.0 release

=== Language changes

* $SAFE is a process global state and we can set 0 again. [Feature #14250]

* refinements take place at block passing.  [Feature #14223]

* `else` without `rescue` is now causes a syntax error.  [EXPERIMENTAL]

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

* An endless range is introduced.  You can write a range that has no end, like `(0..)`.
  The following shows typical use cases.  [Feature #12912]

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

=== Core classes updates (outstanding ones only)

* Array

  * 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 methods:

    * added Binding#source_location.  [Feature #14230]

      This method returns the source location of 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

  * Aliased methods:

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

* Enumerator::Lazy

  * Aliased methods:

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

* Exception

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

* Hash

  * Aliased methods:

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

* Kernel

  * Kernel.#Complex takes :exception option to specify the way of error handling  [Feature #12732]

  * Kernel.#Float takes :exception option to specify the way of error handling  [Feature #12732]

  * Kernel.#Integer takes :exception option to specify the way of error handling  [Feature #12732]

  * Kernel.#Rational takes :exception option to specify the way of error handling  [Feature #12732]

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

* KeyError

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

* NameError

  * NameError#initialize accepts :receiver option to set receiver in Ruby code. [Feature #14313]

* NoMethodError

  * NoMethodError#initialize accepts :receiver option to set receiver in Ruby code. [Feature #14313]

* Proc

  * Proc#call doesn't change $SAFE any more. [Feature #14250]

* Random

  * New methods:

    * added Random.bytes. [Feature #4938]

* String

  * String#split yields each substrings to the block if given. [Feature #4780]

=== Stdlib updates (outstanding ones only)

* ERB

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

  * erb command's -S option is deprecated, which will be removed in the next version.

* FileUtils

  * New method:

    * FileUtils#cp_lr [Feature #4189]

* Matrix

  * New method:

    * Matrix#antisymmetric?

* Set

  * Aliased methods:

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

* URI

  * Add URI::File to handle file URI scheme [Feature #14035]

=== Compatibility issues (excluding feature bug fixes)

* 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]

* Dir

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

=== Stdlib compatibility issues (excluding feature bug fixes)

=== C API updates

=== Supported platform changes

=== Implementation improvements

* Speedup `Proc#call` because we don't need to care about `$SAFE` any more. [Feature #14318]
  With `lc_fizzbuzz` benchmark which uses so many `Proc#call` 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 JIT (Just-in-time) compiler. [Feature #14235] [experimental]
  * `--jit` option is added to enable JIT. `--jit-verbose=1` is good for inspection. See `ruby --help` for others.
  * This JIT relies on C compiler used to build Ruby, on runtime. Only gcc and clang are supported for the JIT
    for now, and MinGW support has some issues.
  * As of 2.6.0-preview1, we're just preparing infrastructure for JIT and very few optimizations are implemented.
    So it's not ready for benchmarking Ruby's JIT performance yet. It's known that current JIT enablement makes
    Rails application slower for now.

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

=== Miscellaneous changes