Add Define A Method On A Struct as a Ruby til

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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-_1145 TILs and counting..._
+_1146 TILs and counting..._
 
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@@ -889,6 +889,7 @@ _1145 TILs and counting..._
 - [Create Thumbnail Image For A PDF](ruby/create-thumbnail-image-for-a-pdf.md)
 - [Defaulting To Frozen String Literals](ruby/defaulting-to-frozen-string-literals.md)
 - [Define A Custom RSpec Matcher](ruby/define-a-custom-rspec-matcher.md)
+- [Define A Method On A Struct](ruby/define-a-method-on-a-struct.md)
 - [Destructuring Arrays In Blocks](ruby/destructuring-arrays-in-blocks.md)
 - [Disassemble Some Codes](ruby/disassemble-some-codes.md)
 - [Double Splat To Merge Hashes](ruby/double-splat-to-merge-hashes.md)

ruby/define-a-method-on-a-struct.md

@@ -0,0 +1,28 @@
+# Define A Method On A Struct
+
+When defining a Ruby `Struct`, you can optionally pass it a block that defines
+any number of methods as instance methods on that `Struct`. They can reference
+the attributes of the `Struct`.
+
+Here is an example of a person `Struct` with a `full_name` method that uses the
+`first_name` and `last_name` attributes.
+
+```ruby
+Person = Struct.new(:first_name, :last_name, :age) do
+  def full_name
+    "#{first_name} #{last_name}"
+  end
+end
+```
+
+This `Struct` can be used like so:
+
+```ruby
+> liz = Person.new("Liz", "Lemon", 39)
+=> #<struct Person first_name="Liz", last_name="Lemon", age=39>
+> liz.full_name
+=> "Liz Lemon"
+```
+
+This is a great way to make a `Struct` just a bit more powerful without having
+to convert it into a full-blown PORO (plain old Ruby object).