Add Jump Out Of A Nested Context With Throw/Catch as a Ruby til

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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@@ -804,6 +804,7 @@ _986 TILs and counting..._
 - [Iterate With An Offset Index](ruby/iterate-with-an-offset-index.md)
 - [Ins And Outs Of Pry](ruby/ins-and-outs-of-pry.md)
 - [Invoking Rake Tasks Multiple Times](ruby/invoking-rake-tasks-multiple-times.md)
+- [Jump Out Of A Nested Context With Throw/Catch](ruby/jump-out-of-a-nested-context-with-throw-catch.md)
 - [Last Raised Exception In The Call Stack](ruby/last-raised-exception-in-the-call-stack.md)
 - [Limit Split](ruby/limit-split.md)
 - [Listing Local Variables](ruby/listing-local-variables.md)

ruby/jump-out-of-a-nested-context-with-throw-catch.md

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+# Jump Out Of A Nested Context With Throw/Catch
+
+Ruby's `throw/catch` construct, not to be confused with its `raise/rescue`
+exception handling syntax, allows you to jump out of a nested context. This is
+similar to [loop
+labels](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/label)
+in other languages.
+
+For example, in my recent [Advent of Code
+solution](https://www.youtube.com/watch?v=Hvp07gTQhF4), I was able to employ
+this construct. Once within a doubly-nested loop, I can `throw` when I find the
+answer I'm looking for to both break out of the loop and return an value.
+
+```ruby
+answer =
+  catch do |obj|
+    input.each_with_index do |input1, x|
+      input.each_with_index do |input2, y|
+        next unless x != y
+
+        next unless input1 + input2 == 2020
+
+        throw(obj, input1 * input2)
+      end
+    end
+
+    raise StandardError, 'No answer found'
+  end
+
+puts answer
+```
+
+If I were to never reach the `throw` before exhausting the doubly-nested loop,
+then the catch would product whatever value is returned within the block. In
+this case, I raise an error because it'd be exceptional for the `throw` to
+never be reached.
+
+[source](https://apidock.com/ruby/Kernel/catch)