ruby/doc/NEWS-2.5.0

# -*- rdoc -*-

= NEWS for Ruby 2.5.0

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 2.4.0 release

=== Language changes

* Top-level constant look-up is removed.  [Feature #11547]

* rescue/else/ensure are allowed inside do/end blocks.  [Feature #12906]

* refinements take place in string interpolations.  [Feature #13812]

=== Core classes updates (outstanding ones only)

* Array

  * New methods:

    * Array#append  [Feature #12746]
    * Array#prepend  [Feature #12746]

* Data

  * Is deprecated. It was a base class for C extensions, and it's not
    necessary to expose in Ruby level. [Feature #3072]

* Exception

  * New methods:

    * Exception#full_message to retrieve a String expression of an exception,
      formatted in the same way in which Ruby prints out an uncaught
      exception.  [Feature #14141] [experimental]

* Dir

  * Dir.glob provides new optional keyword argument, +:base+ .  [Feature #13056]
  * Dir.chdir (without block arg), Dir.open, Dir.new, Dir.mkdir, Dir.rmdir,
    Dir.empty? releases GVL

  * New methods:

    * Dir.children  [Feature #11302]
    * Dir.each_child  [Feature #11302]

* Enumerable

  * Enumerable#any?, Enumerable#all?, Enumerable#none? and Enumerable#one?
    accept a pattern argument. [Feature #11286]

* File

  * File.open accepts +:newline+ option to imply text mode. [Bug #13350]
  * File#path raises an IOError for files opened with
    File::Constants::TMPFILE option. [Feature #13568]
  * File.stat, File.exist? and other <code>rb_stat()</code>-using methods
    release GVL. [Bug #13941]
  * File.rename releases GVL. [Feature #13951]
  * File::Stat#atime, File::Stat#mtime and File::Stat#ctime support fractional
    second timestamps on Windows 8 and later.  [Feature #13726]
  * File::Stat#ino and File.indentical? support ReFS 128bit ino on Windows 8.1
    and later.  [Feature #13731]
  * File.readable?, File.readable_real?, File.writable?, File.writable_real?,
    File.executable?, File.executable_real?, File.mkfifo, File.readlink,
    File.truncate, File#truncate, File.chmod, File.lchmod, File.chown,
    File.lchown, File.unlink, File.utime, File.lstat release GVL

  * New method:

    * File.lutime  [Feature #4052]

* Hash

  * New methods:

    * Hash#transform_keys  [Feature #13583]
    * Hash#transform_keys!  [Feature #13583]
    * Hash#slice  [Feature #8499]

* IO

  * IO.copy_stream tries copy offload with copy_file_range(2) [Feature #13867]

  * New methods:

    * IO#pread  [Feature #4532]
    * IO#pwrite  [Feature #4532]
    * IO#write accepts multiple arguments  [Feature #9323]

* IOError

  * IO#close might raise an error with message "stream closed",
    but it is refined to "stream closed in another thread". The new message
    is more clear for user. [Bug #13405]

* Integer

  * Integer#round, Integer#floor, Integer#ceil and Integer#truncate always
    return an Integer. [Bug #13420]
  * Integer#pow accepts modulo argument for calculating modular
    exponentiation.  [Feature #12508] [Feature #11003]

  * New methods:

    * Integer#allbits?, Integer#anybits?, Integer#nobits? [Feature #12753]
    * Integer.sqrt  [Feature #13219]

* Kernel

  * Kernel#yield_self   [Feature #6721]
  * Kernel#pp  [Feature #14123]
  * Kernel#warn(..., uplevel:n)  [Feature #12882]

* Method

  * New methods:

    * Method#=== that invokes Method#call, as same as Proc#=== [Feature #14142]

* Module

  * Module#attr, Module#attr_accessor, Module#attr_reader and Module#attr_writer
    become public. [Feature #14132]
  * Module#define_method, Module#alias_method, Module#undef_method and
    Module#remove_method become public. [Feature #14133]

* Numeric

  * Numeric#step no longer hides errors from coerce method when
    given a step value which cannot be compared with #> to 0. [Feature #7688]
  * Numerical comparison operators (<,<=,>=,>) no longer hide exceptions
    from #coerce method internally. Return nil in #coerce if the coercion is
    impossible.  [Feature #7688]

* Process

  * Precision of Process.times is improved if getrusage(2) exists. [Feature #11952]

  * New method:

    * Process.last_status as an alias of $? [Feature #14043]

* Range
  * Range#initialize no longer hides exceptions when comparing begin and
    end with #<=> and raise a "bad value for range" ArgumentError
    but instead lets the exception from the #<=> call go through. [Feature #7688]

* Regexp

  * Update to Onigmo 6.1.3-669ac9997619954c298da971fcfacccf36909d05.

    * Support absence operator https://github.com/k-takata/Onigmo/issues/82

  * Support new 5 emoji-related Unicode character properties

* RubyVM::InstructionSequence

  * New method:

    * RubyVM::InstructionSequence#each_child
    * RubyVM::InstructionSequence#trace_points

* String

  * <code>String#-@</code> deduplicates unfrozen strings.  Already-frozen
    strings remain unchanged for compatibility.  [Feature #13077]
  * <code>-"literal"</code> (<code>String#-@</code>) optimized to return the same object
    (same as <code>"literal".freeze</code> in Ruby 2.1+) [Feature #13295]
  * String#casecmp and String#casecmp? return nil for non-string arguments
    instead of raising a TypeError. [Bug #13312]
  * String#start_with? accepts a regexp [Feature #13712]

  * New methods:

    * String#delete_prefix, String#delete_prefix! [Feature #12694]
    * String#delete_suffix, String#delete_suffix! [Feature #13665]
    * String#each_grapheme_cluster and String#grapheme_clusters to
      enumerate grapheme clusters [Feature #13780]
    * String#undump to unescape String#dump'ed string [Feature #12275]

* Struct

  * Struct.new takes `keyword_init: true` option to initialize members
    with keyword arguments. [Feature #11925]

* Regexp/String: Update Unicode version from 9.0.0 to 10.0.0 [Feature #13685]

* Thread

  * Description set by Thread#name= is now visible on Windows 10.

  * New method:
    * Thread#fetch  [Feature #13009]

  * The default of Thread.report_on_exception is now true,
    showing unhandled exceptions terminating threads on $stderr. [Feature #14143]

* Time

  * Time.at receives 3rd argument which specifies the unit of 2nd argument. [Feature #13919]

* KeyError

  * New methods:

    * KeyError#receiver [Feature #12063]
    * KeyError#key      [Feature #12063]

* FrozenError

  * New exception class. [Feature #13224]

=== Stdlib updates (outstanding ones only)

* BigDecimal

  * Update to BigDecimal 1.3.4

  * The following features are added:

    * BigDecimal::VERSION

  * The following features have been deprecated,
    and are planned to be removed in the version 1.4.0:

    * BigDecimal.new

    * BigDecimal.ver

  * BigDecimal#clone and #dup now do not make a new instance,
    but returns the receiver itself.

* Coverage

  * Support branch coverage and method coverage measurement. [Feature #13901]
    Branch coverage tells you which branches are executed, and which not.
    Method coverage tells you which methods are invoked, and which not.
    By running a test suite with this new feature, you can know which branches
    and methods are executed by a test, and evaluate total coverage of a test
    suite more strictly.

    You can specify the measuring target by an option to `Coverage.start`:

        Coverage.start(lines: true, branches: true, methods: true)

    After some Ruby files are loaded, you can use `Coverage.result` to get
    the coverage result:

        Coverage.result
        #=> { "/path/to/file.rb"=>
        #     { :lines => [1, 2, 0, nil, ...],
        #       :branches =>
        #         { [:if, 0, 2, 1, 6, 4] =>
        #             { [:then, 1, 3, 2, 3, 8] => 0,
        #               [:else, 2, 5, 2, 5, 8] => 2
        #             }
        #         },
        #       :methods => {
        #          [Object, :foo, 1, 0, 7, 3] => 2
        #       }
        #     }
        #   }

    The result type of line coverage is not changed; it is just an array that
    contains numbers, which means the count that each line was executed,
    or `nil`s, which means that the line is not relevant.

    The result type of branch coverage is:

        { (jump base) => { (jump target) => (counter) } }

    where jump base and targets have the format

        [type, unique-id, start lineno, start column, end lineno, end column]

    For example, `[:if, 0, 2, 1, 6, 4]` reads an `if` statement that ranges from
    line 2 and column 1, to line 6 and column 4.  `[:then, 1, 3, 2, 3, 8]` reads
    a `then` clause that ranges from line 3 and column 2, to line 3 and column 8.
    Note that lineno starts from 1, and that columnno starts from 0.  So, the
    above example shows a branch from the `if` to the `then` was never executed,
    and a branch from the `if` to the `else` was executed twice.

    The result type of method coverage is:

        { (method key) => (counter) }

    where method key has the format

        [class, method-name, start lineno, start column, end lineno, end column]

    For example, `[Object, :foo, 1, 0, 7, 3]` reads `Object#foo` that ranges from
    line 1 and column 0, to line 7 and column 3.  The above example shows this
    `Object#foo` was invoked twice.

    Note: To keep compatibility, passing no option to `Coverage.start` will measure
    only line coverage, and `Coverage.result` will return the old format:

        Coverage.result
        #=> { "/path/to/file.rb"=> [1, 2, 0, nil, ...] }

* DRb

  * ACL::ACLEntry.new no longer suppresses IPAddr::InvalidPrefixError.

* ERB

  * Add ERB#result_with_hash to render a template with local variables passed
    with a Hash object. [Feature #8631]

  * Default template file encoding is changed from ASCII-8BIT to UTF-8 in erb
    command. [Bug #14095]

  * Carriage returns are changed to be trimmed properly if trim_mode is specified
    and used. Duplicated newlines will be removed on Windows. [Bug #5339] [Bug #11464]

* IPAddr

  * IPAddr no longer accepts invalid address mask. [Bug #13399]
  * IPAddr#ipv4_compat and IPAddr#ipv4_compat? are marked for deprecation. [Bug #13769]

  * New methods:

    * IPAddr#prefix
    * IPAddr#loopback?
    * IPAddr#private? [Feature #11666]
    * IPAddr#link_local? [Feature #10912]

* IRB

  * Print backtrace and error message in reverse order [Feature #8661] [experimental]
  * `binding.irb` automatically requires irb and runs [Bug #13099] [experimental]
  * `binding.irb` on its start shows source around the line where it was called [Feature #14124]

* Matrix

  * New methods:

    * Matrix.combine and Matrix#combine [Feature #10903]
    * Matrix#hadamard_product and Matrix#entrywise_product

* Net::HTTP

  * Net::HTTP.new supports no_proxy parameter [Feature #11195]
  * Net::HTTP#min_version and Net::HTTP#max_version [Feature #9450]
  * Add more HTTP status classes
  * Net::HTTP::STATUS_CODES is added as HTTP Status Code Repository [Misc #12935]
  * Net::HTTP#proxy_user and Net::HTTP#proxy_pass reflect http_proxy environment
    variable if the system's environment variable is multiuser safe. [Bug #12921]

* open-uri
  * URI.open method defined as an alias to open-uri's Kernel.open.
    open-uri's Kernel.open will be deprecated in future.

* OpenSSL

  * Updated Ruby/OpenSSL from version 2.0 to 2.1. Changes are noted in
    "Version 2.1.0" section in ext/openssl/History.md.

* Pathname

  * New method:

    * Pathname#glob [Feature #7360]

* Psych

  * Update to Psych 3.0.2.

    * Convert fallback option to a keyword argument
      https://github.com/ruby/psych/pull/342
    * Add :symbolize_names option to Psych.load, Psych.safe_load like JSON.parse
      https://github.com/ruby/psych/pull/333, https://github.com/ruby/psych/pull/337
    * Add Psych::Handler#event_location
      https://github.com/ruby/psych/pull/326
    * Make frozen string literal = true
      https://github.com/ruby/psych/pull/320
    * Preserve time zone offset when deserializing times
      https://github.com/ruby/psych/pull/316
    * Remove deprecated method aliases for syck gem
      https://github.com/ruby/psych/pull/312

* RbConfig

  * RbConfig::LIMITS is added to provide the limits of C types.
    This is available when rbconfig/sizeof is loaded.

* Ripper

  * Ripper::EXPR_BEG and so on for Ripper#state.

  * New method:

    * Ripper#state to tell the state of scanner. [Feature #13686]

* RDoc

  * Update to RDoc 6.0.1.

    * Replace IRB based lexer with Ripper.
      * https://github.com/ruby/rdoc/pull/512
      * This much improves the speed of generating documents.
      * It also facilitates supporting new syntax in the future.
    * Support many new syntaxes of Ruby from the past few years.
    * Use "frozen_string_literal: true".
      Performance survey: https://gist.github.com/aycabta/abdfaa75ea8a6877eeb734e942e73800
    * Support did_you_mean.

* Rubygems

  * Update to Rubygems 2.7.3.
    * http://blog.rubygems.org/2017/11/28/2.7.3-released.html
    * http://blog.rubygems.org/2017/11/08/2.7.2-released.html
    * http://blog.rubygems.org/2017/11/03/2.7.1-released.html
    * http://blog.rubygems.org/2017/11/01/2.7.0-released.html
    * http://blog.rubygems.org/2017/10/09/2.6.14-released.html
    * http://blog.rubygems.org/2017/08/27/2.6.13-released.html

* SecureRandom

  * New method:

    * SecureRandom.alphanumeric

* Set

  * New methods:

    * Set#to_s as alias to #inspect [Feature #13676]
    * Set#=== as alias to #include? [Feature #13801]
    * Set#reset [Feature #6589]

* StringIO

  * StringIO#write accepts multiple arguments

* StringScanner

  * New methods:

    * StringScanner#size, StringScanner#captures, StringScanner#values_at  [Feature #836]

* URI

  * Relative path operations no longer collapse consecutive slashes to a single slash. [Bug #8352]

* WEBrick

  * Add Server Name Indication (SNI) support [Feature #13729]
  * support Proc objects as body responses [Feature #855]
  * released as a RubyGem [Feature #13173]
  * avoid unintended behavior from Kernel#open [Misc #14216]

* Zlib

  * Zlib::GzipWriter#write accepts multiple arguments

=== Compatibility issues (excluding feature bug fixes)

* Socket

  * BasicSocket#read_nonblock and BasicSocket#write_nonblock no
    longer set the O_NONBLOCK file description flag as side effect
    (on Linux only) [Feature #13362]

* Random

  * Random.raw_seed renamed to become Random.urandom.  It is now
    applicable to non-seeding purposes due to [Bug #9569].

* Socket

  * Socket::Ifaddr#vhid is added [Feature #13803]

* ConditionVariable, Queue and SizedQueue reimplemented for speed.
  They no longer subclass Struct. [Feature #13552]

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

* Gemification

  * Promote following standard libraries to default gems.
    * cmath
    * csv
    * date
    * dbm
    * etc
    * fcntl
    * fiddle
    * fileutils
    * gdbm
    * ipaddr
    * scanf
    * sdbm
    * stringio
    * strscan
    * webrick
    * zlib

* Logger

  * Logger.new("| command") had been working to open a command
    unintentionally. It was prohibited, and now Logger#initialize
    treats a String argument only as a filename, as its specification. [Bug #14212]

* Net::HTTP

  * Net::HTTP#start now passes :ENV to p_addr by default. [Bug #13351]
    To avoid this, pass nil explicitly.

* mathn.rb

  * Removed from stdlib. [Feature #10169]

* Rubygems

  * Removed "ubygems.rb" file from stdlib. It's needless since Ruby 1.9.

=== Supported platform changes

* Drop support of NaCl platform

  * https://bugs.chromium.org/p/chromium/issues/detail?id=239656#c160

=== Implementation improvements

* (This might not be a "user visible feature change" but) Hash class's
  hash function is now SipHash13. [Feature #13017]

* SecureRandom now prefers OS-provided sources than OpenSSL. [Bug #9569]

* Mutex rewritten to be smaller and faster [Feature #13517]

* Performance of block passing using block parameters is improved by
  lazy Proc allocation [Feature #14045]

* Dynamic instrumentation for TracePoint hooks instead of using "trace"
  instruction to avoid overhead [Feature #14104]

* ERB now generates code from a template twice as fast as Ruby 2.4

=== Miscellaneous changes

* Print backtrace and error message in reverse order if $stderr is unchanged
  and a tty. [Feature #8661] [experimental]

* Print error message in bold/underlined text if $stderr is unchanged and a
  tty. [Feature #14140] [experimental]

* configure option --with-ext now mandates its arguments.  So for
  instance if you run ./configure --with-ext=openssl,+ then the
  openssl library is guaranteed compiled, otherwise the build fails
  abnormally.

  Note however to always add the ",+" at the end of the argument.
  Otherwise nothing but openssl are built.  [Feature #13302]