Add Disable Interpolation For A Heredoc String as a Ruby TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1532 TILs and counting..._
+_1533 TILs and counting..._
 
 ---
 
@@ -1223,6 +1223,7 @@ _1532 TILs and counting..._
 - [Define Multiline Strings With Heredocs](ruby/define-multiline-strings-with-heredocs.md)
 - [Destructure The First Item From An Array](ruby/destructure-the-first-item-from-an-array.md)
 - [Destructuring Arrays In Blocks](ruby/destructuring-arrays-in-blocks.md)
+- [Disable Interpolation For A Heredoc String](ruby/disable-interpolation-for-a-heredoc-string.md)
 - [Disassemble Some Codes](ruby/disassemble-some-codes.md)
 - [Double Splat To Merge Hashes](ruby/double-splat-to-merge-hashes.md)
 - [Edit Previous Parts Of The Pry Buffer History](ruby/edit-previous-parts-of-the-pry-buffer-history.md)

ruby/disable-interpolation-for-a-heredoc-string.md

@@ -0,0 +1,41 @@
+# Disable Interpolation For A Heredoc String
+
+As a matter of convenience, a heredoc performs string interpolation by default.
+
+Here is an example of that.
+
+```ruby
+irb(main):087> word = 'taco'
+=> "taco"
+irb(main):088" puts <<-TEXT
+irb(main):089"   I want to eat a #{word}!
+irb(main):090> TEXT
+  I want to eat a taco!
+=> nil
+```
+
+A much less common scenario is that we don't want string interpolation to take
+place. For whatever reason, we want the exact string to be preserved. To
+achieve that, we can wrap the opening heredoc identifier in single quotes.
+
+As you can see, the `#{word}` portion is preserved.
+
+```ruby
+irb(main):091> word = 'taco'
+=> "taco"
+irb(main):092' puts <<-'TEXT'
+irb(main):093'   I want to eat a #{word}!
+irb(main):094> TEXT
+  I want to eat a #{word}!
+=> nil
+```
+
+This syntax puts the heredoc in single-quote mode. I left the IRB line preamble
+in for each codeblock so that you can see the difference. The first example
+(lines 88 and 89) shows the heredoc is double-quoted. The second example (lines
+92 and 93) shows the heredoc is single quoted.
+
+Note: the closing heredoc identifier (`TEXT` in this case) is not wrapped in
+single quotes, just the opening one.
+
+[source](https://ruby-doc.org/3.3.6/syntax/literals_rdoc.html#label-Here+Document+Literals)