# 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. `https://bugs.ruby-lang.org/issues/$FEATURE_OR_BUG_NUMBER`)

## 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 `rb_stat()`-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.identical?` 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 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`

  - `String#-@` deduplicates unfrozen strings. Already-frozen strings remain unchanged for compatibility. [Feature #13077]

  - `-"literal"` (`String#-@`) optimized to return the same object (same as `"literal".freeze` 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 github.com/ruby/psych/pull/342

    - Add :symbolize_names option to `Psych.load`, `Psych.safe_load` like `JSON.parse` github.com/ruby/psych/pull/333, github.com/ruby/psych/pull/337

    - Add `Psych::Handler#event_location` github.com/ruby/psych/pull/326

    - Make frozen string literal = true github.com/ruby/psych/pull/320

    - Preserve time zone offset when deserializing times github.com/ruby/psych/pull/316

    - Remove deprecated method aliases for syck gem 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`.

      - 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: gist.github.com/aycabta/abdfaa75ea8a6877eeb734e942e73800

    - Support did_you_mean.

- Rubygems

  - Update to Rubygems 2.7.3.

    - blog.rubygems.org/2017/11/28/2.7.3-released.html

    - blog.rubygems.org/2017/11/08/2.7.2-released.html

    - blog.rubygems.org/2017/11/03/2.7.1-released.html

    - blog.rubygems.org/2017/11/01/2.7.0-released.html

    - blog.rubygems.org/2017/10/09/2.6.14-released.html

    - 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

  - 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]