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.

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:

> 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).