From 12388e8cc7631f9b0fd56cb79d8c06c4a9c0e0af Mon Sep 17 00:00:00 2001
From: jbranchaud <jbranchaud@gmail.com>
Date: Sat, 30 Jan 2021 22:04:40 -0600
Subject: [PATCH] Add Pattern Matching Values From A Hash as a ruby til

---
 README.md                                |  3 ++-
 ruby/pattern-match-values-from-a-hash.md | 32 ++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 ruby/pattern-match-values-from-a-hash.md

diff --git a/README.md b/README.md
index 6ae989a..555a78e 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://tinyletter.com/jbranchaud).
 
-_1030 TILs and counting..._
+_1031 TILs and counting..._
 
 ---
 
@@ -855,6 +855,7 @@ _1030 TILs and counting..._
 - [Pass A Block To Count](ruby/pass-a-block-to-count.md)
 - [Passing Arbitrary Methods As Blocks](ruby/passing-arbitrary-methods-as-blocks.md)
 - [Passing Arguments To A Rake Task](ruby/passing-arguments-to-a-rake-task.md)
+- [Pattern Match Values From A Hash](ruby/pattern-match-values-from-a-hash.md)
 - [Percent Notation](ruby/percent-notation.md)
 - [Question Mark Operator](ruby/question-mark-operator.md)
 - [Rake Only Lists Tasks With Descriptions](ruby/rake-only-lists-tasks-with-descriptions.md)
diff --git a/ruby/pattern-match-values-from-a-hash.md b/ruby/pattern-match-values-from-a-hash.md
new file mode 100644
index 0000000..d41a244
--- /dev/null
+++ b/ruby/pattern-match-values-from-a-hash.md
@@ -0,0 +1,32 @@
+# Pattern Match Values From A Hash
+
+As of Ruby 3.0.0, the _rightward assignment_ operator (`=>`) was introduced as
+another syntax for assigning values to variables. With it comes an experimental
+pattern matching capability. This pattern matching can be used with hashes to
+extract keyed values into local variables.
+
+Pattern matching with rightward assignment can be done by placing a hash on the
+left-hand side of the `=>` operator and then placing a hash-like listing of
+keys to be matched against.
+
+```ruby
+> some_hash = { name: "Josh", handle: "@jbrancha", age: :unknown }
+=> {:name=>"Josh", :handle=>"@jbrancha", :age=>:unknown}
+> some_hash => {name:, handle:}
+(irb):3: warning: One-line pattern matching is experimental, and the behavior may change in future versions of Ruby!
+=> nil
+> name
+=> "Josh"
+> handle
+=> "@jbrancha"
+```
+
+This example extracts `name` and `handle` as local variables assigned with the
+values of the those keys from the hash.
+
+Note that this feature is _experimental_.
+
+Also note that referencing a key that doesn't exist in a pattern matching
+statement will raise a `NoMatchingPatternError`.
+
+[source](https://www.ruby-lang.org/en/news/2020/12/25/ruby-3-0-0-released/)