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@@ -1,5 +1,210 @@
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-
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include::{partialsdir}/entities.adoc[]
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[[sect-ruby]]
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- = Ruby
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+ = Ruby 2.7
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+
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+ Fedora 32 provides Ruby 2.7 version. With this major update from Ruby 2.6, Fedora becomes the superior Ruby development platform.
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+ [[back]]
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+ == Changes since Ruby 2.6:
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+
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+ Ruby 2.7 comes with several new features and performance improvements.
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+
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+ === New features:
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+
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+ * <<Pattern,Pattern Matching>>
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+ * <<REPL,REPL improvement>>
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+ * <<GC,Compaction GC>>
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+ * <<Separation,Separation of positional and keyword arguments>>
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+
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+ === Performance improvements:
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+
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+ * JIT [Experimental]
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+ * Fiber’s cache strategy is changed and fiber creation is speeded up.
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+ * `Module#name`, `true.to_s`, `false.to_s`, and `nil.to_s` now always return a frozen String. The returned String is always the same for a given object. [Experimental]
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+ * The performance of `Monitor` and `MonitorMixin` is improved.
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+ * The performance of `CGI.escapeHTML` is improved.
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+ * `Per-call-site` method cache, which has been there since around 1.9, was improved: cache hit rate raised from 89% to 94%.
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+ * `RubyVM::InstructionSequence#to_binary` method generates compiled binary. The binary size is reduced.
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+
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+ === Other notable changes:
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+
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+
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+ * Some standard libraries are updated.
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+ ** Bundler 2.1.2
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+ ** RubyGems 3.1.2
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+ ** Racc 1.4.15
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+ ** CSV 3.1.2
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+ ** REXML 3.2.3
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+ ** RSS 0.2.8
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+ ** StringScanner 1.0.3
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+ ** Some other libraries that have no original version are also updated.
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+ * The following libraries are no longer bundled gems. Install corresponding gems to use these features.
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+ ** CMath (cmath gem)
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+ ** Scanf (scanf gem)
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+ ** Shell (shell gem)
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+ ** Synchronizer (sync gem)
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+ ** ThreadsWait (thwait gem)
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+ ** E2MM (e2mmap gem)
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+
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+ * `profile.rb` was removed from standard library.
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+ * Promote `stdlib` to default gems
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+ ** The following default gems were published on rubygems.org
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+ *** benchmark
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+ *** cgi
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+ *** delegate
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+ *** getoptlong
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+ *** net-pop
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+ *** net-smtp
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+ *** open3
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+ *** pstore
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+ *** singleton
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+ ** The following default gems were only promoted at ruby-core, but not yet published on rubygems.org.
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+ *** monitor
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+ *** observer
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+ *** timeout
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+ *** tracer
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+ *** uri
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+ *** yaml
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+
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+ * `Proc.new` and `proc` with no block in a method called with a block is warned now.
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+
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+ * lambda with no block in a method called with a block raises an exception.
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+
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+ * Update Unicode version and Emoji version from 11.0.0 to 12.0.0.
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+
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+ * Update Unicode version to 12.1.0, adding support for U+32FF SQUARE ERA NAME REIWA.
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+
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+ * `Date.jisx0301`, `Date#jisx0301`, and `Date.parse` support the new Japanese era.
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+
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+ * Require compilers to support C99.
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+
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+
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+ == Detailed changes:
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+
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+
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+ [[Pattern]]
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+ === Pattern Matching [Experimental]
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+
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+
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+
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+ Pattern matching, a widely used feature in functional programming languages, is introduced as an experimental feature. It can traverse a given object and assign it's value if it matches a pattern.
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+
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+ [source,json]
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+ ----
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+ require "json"
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+
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+ json = <<END
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+ {
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+ "name": "Alice",
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+ "age": 30,
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+ "children": [{ "name": "Bob", "age": 2 }]
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+ }
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+ END
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+
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+ case JSON.parse(json, symbolize_names: true)
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+ in {name: "Alice", children: [{name: "Bob", age: age}]}
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+ p age #=> 2
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+ end
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+ ----
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+
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+
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+ [[REPL]]
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+ === REPL improvement
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+
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+
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+ `irb`, the bundled interactive environment (REPL; Read-Eval-Print-Loop), now supports multi-line editing. It is powered by `reline`, a `readline` -compatible library implemented in pure Ruby. It also provides rdoc integration. In `irb` you can display the reference for a given class, module, or method.
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+
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+
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+ [[GC]]
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+ === Compaction GC
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+
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+
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+ This release introduces Compaction GC which can defragment a fragmented memory space.
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+
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+ Some multi-threaded Ruby programs may cause memory fragmentation, leading to high memory usage and degraded speed.
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+
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+ The `GC.compact` method is introduced for compacting the heap. This function compacts live objects in the heap so that fewer pages may be used, and the heap may be more CoW (copy-on-write) friendly.
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+
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+
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+
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+ [[Separation]]
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+ === Separation of positional and keyword arguments
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+
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+
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+ Automatic conversion of keyword arguments and positional arguments is deprecated, and conversion will be removed in Ruby 3.
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+
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+ ==== Changes:
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+
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+
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+
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+ * When a method call passes a Hash at the last argument, and when it passes no keywords, and when the called method accepts keywords, a warning is emitted. To continue treating the hash as keywords, add a double splat operator to avoid the warning and ensure correct behavior in Ruby 3.
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+
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+ [source,ruby]
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+ ----
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+ def foo(key: 42); end; foo({key: 42}) # warned
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+ def foo(**kw); end; foo({key: 42}) # warned
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+ def foo(key: 42); end; foo(**{key: 42}) # OK
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+ def foo(**kw); end; foo(**{key: 42}) # OK
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+ ----
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+
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+ * When a method call passes keywords to a method that accepts keywords, but it does not pass enough required positional arguments, the keywords are treated as a final required positional argument, and a warning is emitted. Pass the argument as a hash instead of keywords to avoid the warning and ensure correct behavior in Ruby 3.
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+
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+ [source,ruby]
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+ ----
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+ def foo(h, **kw); end; foo(key: 42) # warned
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+ def foo(h, key: 42); end; foo(key: 42) # warned
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+ def foo(h, **kw); end; foo({key: 42}) # OK
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+ def foo(h, key: 42); end; foo({key: 42}) # OK
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+ ----
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+
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+ * When a method accepts specific keywords but not a keyword splat, and a hash or keywords splat is passed to the method that includes both Symbol and non-Symbol keys, the hash will continue to be split, and a warning will be emitted. You will need to update the calling code to pass separate hashes to ensure correct behavior in Ruby 3.
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+
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+ [source,ruby]
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+ ----
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+ def foo(h={}, key: 42); end; foo("key" => 43, key: 42) # warned
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+ def foo(h={}, key: 42); end; foo({"key" => 43, key: 42}) # warned
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+ def foo(h={}, key: 42); end; foo({"key" => 43}, key: 42) # OK
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+ ----
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+
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+ * If a method does not accept keywords, and is called with keywords, the keywords are still treated as a positional hash, with no warning. This behavior will continue to work in Ruby 3.
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+
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+ [source,ruby]
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+ ----
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+ def foo(opt={}); end; foo( key: 42 ) # OK
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+ ----
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+
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+ * Non-symbols are allowed as keyword argument keys if the method accepts arbitrary keywords.
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+
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+ [source,ruby]
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+ ----
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+ def foo(**kw); p kw; end; foo("str" => 1) #=> {"str"=>1}
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+ ----
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+
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+ * `**nil` is allowed in method definitions to explicitly mark that the method accepts no keywords. Calling such a method with keywords will result in an `ArgumentError`.
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+
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+ [source,ruby]
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+ ----
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+ def foo(h, **nil); end; foo(key: 1) # ArgumentError
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+ def foo(h, **nil); end; foo(**{key: 1}) # ArgumentError
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+ def foo(h, **nil); end; foo("str" => 1) # ArgumentError
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+ def foo(h, **nil); end; foo({key: 1}) # OK
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+ def foo(h, **nil); end; foo({"str" => 1}) # OK
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+ ----
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+
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+ * Passing an empty keyword splat to a method that does not accept keywords no longer passes an empty hash, unless the empty hash is necessary for a required parameter, in which case a warning will be emitted. Remove the double splat to continue passing a positional hash.
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+
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+ [source,ruby]
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+ ----
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+ h = {}; def foo(*a) a end; foo(**h) # []
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+ h = {}; def foo(a) a end; foo(**h) # {} and warning
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+ h = {}; def foo(*a) a end; foo(h) # [{}]
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+ h = {}; def foo(a) a end; foo(h) # {}
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+ ----
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+
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+ If you want to disable the deprecation warnings, please use a command-line argument -W:no-deprecated or add Warning[:deprecated] = false to your code.
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+
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+ See the link:https://www.ruby-lang.org/en/news/2019/12/25/ruby-2-7-0-released/[upstream release announcement] for more detailed information about this release.
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+
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+ <<back,back to top>>
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+
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+
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roypen
commented 4 years ago
Release notes for Ruby 2.7. Issue #428