From: "NARUSE, Yui" <naruse@...>
Date: 2016-12-25T08:06:41+09:00
Subject: [ruby-core:78822] Ruby 2.4.0 Released

We are pleased to announce the release of Ruby 2.4.0.

Ruby 2.4.0 is the first stable release of the Ruby 2.4 series.
It introduces many new features, for example:

## [Introduce hash table improvement (by Vladimir
Makarov)](https://bugs.ruby-lang.org/issues/12142)

Improve the internal structure of hash table (st_table) by introducing
open addressing
and an inclusion order array.
This improvement has been discussed with many people, especially with
Yura Sokolov.

## Binding#irb: Start a REPL session similar to `binding.pry`

While you are debugging, you may often use `p` to see the value of variables.
With [pry](https://github.com/pry/pry) you can use `binding.pry` in
your application
to launch a REPL and run any Ruby code.
[r56624](https://github.com/ruby/ruby/commit/493e48897421d176a8faf0f0820323d79ecdf94a)
introduces `binding.irb` which behaves like that with irb.

## [Unify Fixnum and Bignum into
Integer](https://bugs.ruby-lang.org/issues/12005)

Though [ISO/IEC
30170:2012](http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=59579)
doesn't specify details of the Integer class,
Ruby had two visible Integer classes: Fixnum and Bignum.
Ruby 2.4 unifies them into Integer.
All C extensions which touch the Fixnum or Bignum class need to be fixed.

See also [the ticket](https://bugs.ruby-lang.org/issues/12005) and
[akr's slides](http://www.a-k-r.org/pub/2016-09-08-rubykaigi-unified-integer.pdf).

## [String supports Unicode case
mappings](https://bugs.ruby-lang.org/issues/10085)

`String/Symbol#upcase/downcase/swapcase/capitalize(!)` now handle
Unicode case mappings instead of only ASCII case mappings.

## Performance improvements

Ruby 2.4 also contains the following performance improvements including
language changes:

### [Array#max, Array#min](https://bugs.ruby-lang.org/issues/12172)

`[x, y].max` and `[x, y].min` are optimized to not create a temporary array
under certain conditions.

### [Regexp#match?](https://bugs.ruby-lang.org/issues/8110)

Added `Regexp#match?`, which executes a regexp match without creating
a back reference object and changing `$~` to reduce object allocation.

### Other performance improvements

* [speed up instance variable access](https://bugs.ruby-lang.org/issues/12274)

## Debugging

### [Thread#report_on_exception and
Thread.report_on_exception](https://bugs.ruby-lang.org/issues/6647)

Ruby ignores exceptions in threads unless another thread explicitly joins them.
With `report_on_exception = true`,
you can notice if a thread has died due to an unhandled exception.

Send us feedback what should be the default for `report_on_exception`
and about report-on-GC, which shows a report when a thread is
garbage collected without join.

### [Thread deadlock detection now shows threads with their backtrace
and dependency](https://bugs.ruby-lang.org/issues/8214)

Ruby has deadlock detection around waiting threads, but its report doesn't
include enough information for debugging.
Ruby 2.4's deadlock detection shows threads with their backtrace and
dependent threads.

## Other notable changes since 2.3

* Support OpenSSL 1.1.0 (drop support for 0.9.7 or prior)
* ext/tk is now removed from stdlib [Feature
#8539](https://bugs.ruby-lang.org/issues/8539)
* XMLRPC is now removed from stdlib [Feature
#12160](https://bugs.ruby-lang.org/issues/12160)

See [NEWS](https://github.com/ruby/ruby/blob/v2_4_0/NEWS)
or commit logs for details.

With those changes,
[2523 files changed, 289129 insertions(+), 84670
deletions(-)](https://github.com/ruby/ruby/compare/v2_3_0...v2_4_0)
since Ruby 2.3.0!

Merry Christmas, Happy Holidays, and enjoy programming with Ruby 2.4!

## Download

* <https://cache.ruby-lang.org/pub/ruby/2.4/ruby-2.4.0.tar.bz2>

      SIZE:   12572424 bytes
      SHA1:   944d2588308391b20a89642472454d1dfe7b2360
      SHA256: 440bbbdc49d08d3650f340dccb35986d9399177ad69a204def56e5d3954600cf
      SHA512: bef7bb53f63fb74073d071cc125fb67b273ed0779ef43c2d2969089b9ca21fff1bd012281c5b748f7a3c24dd26e71730d7248c05a01cb23ab2089eb4d02115fe

* <https://cache.ruby-lang.org/pub/ruby/2.4/ruby-2.4.0.tar.gz>

      SIZE:   14104044 bytes
      SHA1:   d44a3c50a0e742341ed3033d5db79d865151a4f4
      SHA256: 152fd0bd15a90b4a18213448f485d4b53e9f7662e1508190aa5b702446b29e3d
      SHA512: 21c9f596b42dd9cba7a53963a59fed0c2e0c1eb960a4ac7087ea3eaa991ce9252d32639e1edcb75b1d709bc07c4820a6dc336ab427d0643c6e6498e0eacdbc8b

* <https://cache.ruby-lang.org/pub/ruby/2.4/ruby-2.4.0.tar.xz>

      SIZE:   9906880 bytes
      SHA1:   038804bbd0e77508dd2510b729a9f3b325489b2e
      SHA256: 3a87fef45cba48b9322236be60c455c13fd4220184ce7287600361319bb63690
      SHA512: 975a5388592adc038461e0acebb6c0efee242891b2ea8621476401458efe2bc0fdd317d3bf99beb745b0b3808410efdff33862da29c95c027f457943721e3ab6

* <https://cache.ruby-lang.org/pub/ruby/2.4/ruby-2.4.0.zip>

      SIZE:   15758757 bytes
      SHA1:   29e1bab11551011718c35a51827edcb55bd656fc
      SHA256: 5c2bbfa26fd6a15a2d70961874b0f3a386206fcc5f698e240dd8b0c9f0f18c5e
      SHA512: 31d932372ce490eeac0a70bc8dcf842909a90435422398d069c05cf01d994936064b8f4e60879e28a8655c1296eb8e180e348cb95e001ed6ca73cda0ff77de23

-- 
NARUSE, Yui  <naruse@airemix.jp>

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