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|
# NEWS for Ruby 3.1.0
This document is a list of user-visible feature changes
since the **3.0.0** release, except for bug fixes.
Note that each entry is kept to a minimum, see links for details.
## Language changes
* The block argument can now be anonymous if the block will
only be passed to another method. [[Feature #11256]]
```ruby
def foo(&)
bar(&)
end
```
* Pin operator now takes an expression. [[Feature #17411]]
```ruby
Prime.each_cons(2).lazy.find_all{_1 in [n, ^(n + 2)]}.take(3).to_a
#=> [[3, 5], [5, 7], [11, 13]]
```
* Pin operator now supports instance, class, and global variables.
[[Feature #17724]]
```ruby
@n = 5
Prime.each_cons(2).lazy.find{_1 in [n, ^@n]}
#=> [3, 5]
```
* One-line pattern matching is no longer experimental.
* Parentheses can be omitted in one-line pattern matching.
[[Feature #16182]]
```ruby
[0, 1] => _, x
{y: 2} => y:
x #=> 1
y #=> 2
```
* Multiple assignment evaluation order has been made consistent with
single assignment evaluation order. With single assignment, Ruby
uses a left-to-right evaluation order. With this code:
```ruby
foo[0] = bar
```
The following evaluation order is used:
1. `foo`
2. `bar`
3. `[]=` called on the result of `foo`
In Ruby before 3.1.0, multiple assignment did not follow this
evaluation order. With this code:
```ruby
foo[0], bar.baz = a, b
```
Versions of Ruby before 3.1.0 would evaluate in the following
order
1. `a`
2. `b`
3. `foo`
4. `[]=` called on the result of `foo`
5. `bar`
6. `baz=` called on the result of `bar`
Starting in Ruby 3.1.0, the evaluation order is now consistent with
single assignment, with the left-hand side being evaluated before
the right-hand side:
1. `foo`
2. `bar`
3. `a`
4. `b`
5. `[]=` called on the result of `foo`
6. `baz=` called on the result of `bar`
[[Bug #4443]]
* Values in Hash literals and keyword arguments can be omitted.
[[Feature #14579]]
For example,
* `{x:, y:}` is a syntax sugar of `{x: x, y: y}`.
* `foo(x:, y:)` is a syntax sugar of `foo(x: x, y: y)`.
Constant names, local variable names, and method names are allowed as
key names. Note that a reserved word is considered as a local
variable or method name even if it's a pseudo variable name such as
`self`.
* Non main-Ractors can get instance variables (ivars) of classes/modules
if ivars refer to shareable objects.
[[Feature #17592]]
* A command syntax is allowed in endless method definitions, i.e.,
you can now write `def foo = puts "Hello"`.
Note that `private def foo = puts "Hello"` does not parse.
[[Feature #17398]]
## Command line options
* `--disable-gems` is now explicitly declared as "just for debugging".
Never use it in any real-world codebase.
[[Feature #17684]]
## Core classes updates
Note: We're only listing outstanding class updates.
* Array
* Array#intersect? is added. [[Feature #15198]]
* Class
* Class#subclasses, which returns an array of classes
directly inheriting from the receiver, not
including singleton classes.
[[Feature #18273]]
```ruby
class A; end
class B < A; end
class C < B; end
class D < A; end
A.subclasses #=> [D, B]
B.subclasses #=> [C]
C.subclasses #=> []
```
* Enumerable
* Enumerable#compact is added. [[Feature #17312]]
* Enumerable#tally now accepts an optional hash to count. [[Feature #17744]]
* Enumerable#each_cons and each_slice to return a receiver. [[GH-1509]]
```ruby
[1, 2, 3].each_cons(2){}
# 3.0 => nil
# 3.1 => [1, 2, 3]
[1, 2, 3].each_slice(2){}
# 3.0 => nil
# 3.1 => [1, 2, 3]
```
* Enumerator::Lazy
* Enumerator::Lazy#compact is added. [[Feature #17312]]
* File
* File.dirname now accepts an optional argument for the level to
strip path components. [[Feature #12194]]
* GC
* "GC.measure_total_time = true" enables the measurement of GC.
Measurement can introduce overhead. It is enabled by default.
GC.measure_total_time returns the current setting.
GC.stat[:time] or GC.stat(:time) returns measured time
in milli-seconds. [[[Feature #10917]]]
* GC.total_time returns measured time in nano-seconds. [[[Feature #10917]]]
* Integer
* Integer.try_convert is added. [[Feature #15211]]
* Kernel
* Kernel#load now accepts a module as the second argument,
and will load the file using the given module as the
top-level module. [[Feature #6210]]
* Marshal
* Marshal.load now accepts a `freeze: true` option.
All returned objects are frozen except for `Class` and
`Module` instances. Strings are deduplicated. [[Feature #18148]]
* MatchData
* MatchData#match is added [[Feature #18172]]
* MatchData#match_length is added [[Feature #18172]]
* Method/UnboundMethod
* Method#public?, Method#private?, Method#protected?,
UnboundMethod#public?, UnboundMethod#private?,
UnboundMethod#protected? have been added. [[Feature #11689]]
* Module
* Module#prepend now modifies the ancestor chain if the receiver
already includes the argument. Module#prepend still does not
modify the ancestor chain if the receiver has already prepended
the argument. [[Bug #17423]]
* Module#private, #public, #protected, and #module_function will
now return their arguments. If a single argument is given, it
is returned. If no arguments are given, nil is returned. If
multiple arguments are given, they are returned as an array.
[[Feature #12495]]
* Process
* Process.\_fork is added. This is a core method for fork(2).
Do not call this method directly; it is called by existing
fork methods: Kernel.#fork, Process.fork, and IO.popen("-").
Application monitoring libraries can overwrite this method to
hook fork events. [[Feature #17795]]
* Struct
* Passing only keyword arguments to Struct#initialize is warned.
You need to use a Hash literal to set a Hash to a first member.
[[Feature #16806]]
* StructClass#keyword_init? is added [[Feature #18008]]
* String
* Update Unicode version to 13.0.0 [[Feature #17750]]
and Emoji version to 13.0 [[Feature #18029]]
* String#unpack and String#unpack1 now accept an `offset:` keyword
argument to start the unpacking after an arbitrary number of bytes
have been skipped. If `offset` is outside of the string bounds
`ArgumentError` is raised. [[Feature #18254]]
* Queue
* Queue#initialize now accepts an Enumerable of initial values.
[[Feature #17327]]
* Thread
* Thread#native_thread_id is added. [[Feature #17853]]
* Thread::Backtrace
* Thread::Backtrace.limit, which returns the value to limit backtrace
length set by `--backtrace-limit` command line option, is added.
[[Feature #17479]]
* Time
* Time.new now accepts optional `in:` keyword argument for the
timezone, as well as `Time.at` and `Time.now`, so that is now
you can omit minor arguments to `Time.new`. [[Feature #17485]]
* Time#strftime supports RFC 3339 UTC for unknown offset local
time, `-0000`, as `%-z`. [[Feature #17544]]
* TracePoint
* TracePoint.allow_reentry is added to allow reenter while TracePoint
callback.
[[Feature #15912]]
* $LOAD_PATH
* $LOAD_PATH.resolve_feature_path does not raise. [[Feature #16043]]
* Fiber Scheduler
* Add support for `Addrinfo.getaddrinfo` using `address_resolve` hook.
[[Feature #17370]]
* Introduce non-blocking `Timeout.timeout` using `timeout_after` hook.
[[Feature #17470]]
* Introduce new scheduler hooks `io_read` and `io_write` along with a
low level `IO::Buffer` for zero-copy read/write. [[Feature #18020]]
* IO hooks `io_wait`, `io_read`, `io_write`, receive the original IO object
where possible. [[Bug #18003]]
* Make `Monitor` fiber-safe. [[Bug #17827]]
* Replace copy coroutine with pthread implementation. [[Feature #18015]]
* Refinement
* New class which represents a module created by Module#refine.
`include` and `prepend` are deprecated, and `import_methods` is added
instead. [[Bug #17429]]
## Stdlib updates
* The following default gem are updated.
* RubyGems 3.3.1
* base64 0.1.1
* benchmark 0.2.0
* bigdecimal 3.1.1
* bundler 2.3.1
* cgi 0.3.1
* csv 3.2.1
* date 3.2.2
* did_you_mean 1.6.0.pre.alpha
* digest 3.1.0.pre3
* drb 2.1.0
* erb 2.2.3
* error_highlight 0.3.0
* etc 1.3.0
* fcntl 1.0.1
* fiddle 1.1.0
* fileutils 1.6.0
* find 0.1.1
* io-console 0.5.9
* io-wait 0.2.1
* ipaddr 1.2.3
* irb 1.3.8.pre.11
* json 2.6.1
* logger 1.5.0
* net-http 0.2.0
* net-protocol 0.1.2
* nkf 0.1.1
* open-uri 0.2.0
* openssl 3.0.0.pre
* optparse 0.2.0
* ostruct 0.5.2
* pathname 0.2.0
* pp 0.3.0
* prettyprint 0.1.1
* psych 4.0.3
* racc 1.6.0
* rdoc 6.3.2
* readline-ext 0.1.3
* reline 0.2.8.pre.11
* resolv 0.2.1
* rinda 0.1.1
* ruby2_keywords 0.0.5
* securerandom 0.1.1
* set 1.0.2
* stringio 3.0.1
* strscan 3.0.1
* tempfile 0.1.2
* time 0.2.0
* timeout 0.2.0
* tmpdir 0.1.2
* un 0.2.0
* uri 0.11.0
* yaml 0.2.0
* zlib 2.1.1
* The following bundled gems are updated.
* minitest 5.15.0
* power_assert 2.0.1
* rake 13.0.6
* test-unit 3.5.3
* rexml 3.2.5
* rbs 1.8.1
* typeprof 0.21.1
* The following default gems are now bundled gems.
* net-ftp 0.1.3
* net-imap 0.2.2
* net-pop 0.1.1
* net-smtp 0.3.1
* matrix 0.4.2
* prime 0.1.2
* debug 1.4.0
* Coverage measurement now supports suspension. You can use `Coverage.suspend`
to stop the measurement temporarily, and `Coverage.resume` to restart it.
See [[Feature #18176]] in detail.
* Random::Formatter is moved to random/formatter.rb, so that you can
use `Random#hex`, `Random#base64`, and so on without SecureRandom.
[[Feature #18190]]
## Compatibility issues
Note: Excluding feature bug fixes.
* `rb_io_wait_readable`, `rb_io_wait_writable` and `rb_wait_for_single_fd` are
deprecated in favour of `rb_io_maybe_wait_readable`,
`rb_io_maybe_wait_writable` and `rb_io_maybe_wait` respectively.
`rb_thread_wait_fd` and `rb_thread_fd_writable` are deprecated. [[Bug #18003]]
## Stdlib compatibility issues
* `ERB#initialize` warns `safe_level` and later arguments even without -w.
[[Feature #14256]]
* `lib/debug.rb` is replaced with `debug.gem`
* `Kernel#pp` in `lib/pp.rb` uses the width of `IO#winsize` by default.
This means that the output width is automatically changed depending on
your terminal size. [[Feature #12913]]
* Psych 4.0 changes `Psych.load` as `safe_load` by the default.
You may need to use Psych 3.3.2 for migrating to this behavior.
[[Bug #17866]]
## C API updates
* Documented. [[GH-4815]]
* `rb_gc_force_recycle` is deprecated and has been changed to a no-op.
[[Feature #18290]]
## Implementation improvements
* `instance_eval` and `instance_exec` now only allocate a singleton class when
required, avoiding extra objects and improving performance. [[GH-5146]]
* The performance of `Struct` accessors is improved. [[GH-5131]]
* `mandatory_only?` builtin special form to improve performance on
builtin methods. [[GH-5112]]
* Experimental feature Variable Width Allocation in the garbage collector.
This feature is turned off by default and can be enabled by compiling Ruby
with flag `USE_RVARGC=1` set. [[Feature #18045]] [[Feature #18239]]
## JIT
* Rename Ruby 3.0's `--jit` to `--mjit`, and alias `--jit` to `--yjit`
on non-Windows x86-64 platforms and to `--mjit` on others.
### MJIT
* The default `--mjit-max-cache` is changed from 100 to 10000.
* JIT-ed code is no longer cancelled when a TracePoint for class events
is enabled.
* The JIT compiler no longer skips compilation of methods longer than
1000 instructions.
* `--mjit-verbose` and `--mjit-warning` output "JIT cancel" when JIT-ed
code is disabled because TracePoint or GC.compact is used.
### YJIT: New experimental in-process JIT compiler
New JIT compiler available as an experimental feature. [[Feature #18229]]
See [this blog post](https://shopify.engineering/yjit-just-in-time-compiler-cruby
) introducing the project.
* Disabled by default, use `--yjit` command-line option to enable YJIT.
* Performance improvements on most real-world software, up to 22% on railsbench, 39% on liquid-render.
* Fast warm-up times.
* Limited to macOS & Linux on x86-64 platforms for now.
## Static analysis
### RBS
* [rbs collection](https://github.com/ruby/rbs/blob/master/docs/collection.md) has been introduced to manage gems’ RBSs.
* Many signatures for built-in and standard libraries have been added/updated.
* It includes many bug fixes and performance improvements too.
See the [CHANGELOG.md](https://github.com/ruby/rbs/blob/master/CHANGELOG.md) for more information.
### TypeProf
* [Experimental IDE support](https://github.com/ruby/typeprof/blob/master/doc/ide.md) has been implemented.
* Many bug fixes and performance improvements since Ruby 3.0.0.
## Debugger
* A new debugger [debug.gem](https://github.com/ruby/debug) is bundled.
debug.gem is a fast debugger implementation, and it provides many features
like remote debugging, colorful REPL, IDE (VSCode) integration, and more.
It replaces `lib/debug.rb` standard library.
* `rdbg` command is also installed into `bin/` directory to start and control
debugging execution.
## error_highlight
A built-in gem called error_highlight has been introduced.
It shows fine-grained error locations in the backtrace.
Example: `title = json[:article][:title]`
If `json` is nil, it shows:
```
$ ruby test.rb
test.rb:2:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError)
title = json[:article][:title]
^^^^^^^^^^
```
If `json[:article]` returns nil, it shows:
```
$ ruby test.rb
test.rb:2:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError)
title = json[:article][:title]
^^^^^^^^
```
This feature is enabled by default.
You can disable it by using a command-line option `--disable-error_highlight`.
See [the repository](https://github.com/ruby/error_highlight) in detail.
## Miscellaneous changes
* lib/objspace/trace.rb is added, which is a tool for tracing the object
allocation. Just by requiring this file, tracing is started *immediately*.
Just by `Kernel#p`, you can investigate where an object was created.
Note that just requiring this file brings a large performance overhead.
This is only for debugging purposes. Do not use this in production.
[[Feature #17762]]
* Now exceptions raised in finalizers will be printed to `STDERR`, unless
`$VERBOSE` is `nil`. [[Feature #17798]]
* `ruby -run -e httpd` displays URLs to access. [[Feature #17847]]
* Add `ruby -run -e colorize` to colorize Ruby code using
`IRB::Color.colorize_code`.
[Bug #4443]: https://bugs.ruby-lang.org/issues/4443
[Feature #6210]: https://bugs.ruby-lang.org/issues/6210
[Feature #10917]: https://bugs.ruby-lang.org/issues/10917
[Feature #11256]: https://bugs.ruby-lang.org/issues/11256
[Feature #11689]: https://bugs.ruby-lang.org/issues/11689
[Feature #12194]: https://bugs.ruby-lang.org/issues/12194
[Feature #12495]: https://bugs.ruby-lang.org/issues/12495
[Feature #12913]: https://bugs.ruby-lang.org/issues/12913
[Feature #14256]: https://bugs.ruby-lang.org/issues/14256
[Feature #14579]: https://bugs.ruby-lang.org/issues/14579
[Feature #15198]: https://bugs.ruby-lang.org/issues/15198
[Feature #15211]: https://bugs.ruby-lang.org/issues/15211
[Feature #15912]: https://bugs.ruby-lang.org/issues/15912
[Feature #16043]: https://bugs.ruby-lang.org/issues/16043
[Feature #16182]: https://bugs.ruby-lang.org/issues/16182
[Feature #16806]: https://bugs.ruby-lang.org/issues/16806
[Feature #17312]: https://bugs.ruby-lang.org/issues/17312
[Feature #17327]: https://bugs.ruby-lang.org/issues/17327
[Feature #17370]: https://bugs.ruby-lang.org/issues/17370
[Feature #17398]: https://bugs.ruby-lang.org/issues/17398
[Feature #17411]: https://bugs.ruby-lang.org/issues/17411
[Bug #17423]: https://bugs.ruby-lang.org/issues/17423
[Bug #17429]: https://bugs.ruby-lang.org/issues/17429
[Feature #17470]: https://bugs.ruby-lang.org/issues/17470
[Feature #17479]: https://bugs.ruby-lang.org/issues/17479
[Feature #17485]: https://bugs.ruby-lang.org/issues/17485
[Feature #17544]: https://bugs.ruby-lang.org/issues/17544
[Feature #17592]: https://bugs.ruby-lang.org/issues/17592
[Feature #17684]: https://bugs.ruby-lang.org/issues/17684
[Feature #17724]: https://bugs.ruby-lang.org/issues/17724
[Feature #17744]: https://bugs.ruby-lang.org/issues/17744
[Feature #17750]: https://bugs.ruby-lang.org/issues/17750
[Feature #17762]: https://bugs.ruby-lang.org/issues/17762
[Feature #17795]: https://bugs.ruby-lang.org/issues/17795
[Feature #17798]: https://bugs.ruby-lang.org/issues/17798
[Bug #17827]: https://bugs.ruby-lang.org/issues/17827
[Feature #17847]: https://bugs.ruby-lang.org/issues/17847
[Feature #17853]: https://bugs.ruby-lang.org/issues/17853
[Bug #17866]: https://bugs.ruby-lang.org/issues/17866
[Bug #18003]: https://bugs.ruby-lang.org/issues/18003
[Feature #18008]: https://bugs.ruby-lang.org/issues/18008
[Feature #18015]: https://bugs.ruby-lang.org/issues/18015
[Feature #18020]: https://bugs.ruby-lang.org/issues/18020
[Feature #18029]: https://bugs.ruby-lang.org/issues/18029
[Feature #18045]: https://bugs.ruby-lang.org/issues/18045
[Feature #18148]: https://bugs.ruby-lang.org/issues/18148
[Feature #18172]: https://bugs.ruby-lang.org/issues/18172
[Feature #18176]: https://bugs.ruby-lang.org/issues/18176
[Feature #18190]: https://bugs.ruby-lang.org/issues/18190
[Feature #18229]: https://bugs.ruby-lang.org/issues/18229
[Feature #18239]: https://bugs.ruby-lang.org/issues/18239
[Feature #18254]: https://bugs.ruby-lang.org/issues/18254
[Feature #18273]: https://bugs.ruby-lang.org/issues/18273
[Feature #18290]: https://bugs.ruby-lang.org/issues/18290
[GH-1509]: https://github.com/ruby/ruby/pull/1509
[GH-4815]: https://github.com/ruby/ruby/pull/4815
[GH-5112]: https://github.com/ruby/ruby/pull/5112
[GH-5131]: https://github.com/ruby/ruby/pull/5131
[GH-5146]: https://github.com/ruby/ruby/pull/5146
|