Ruby Language Multiline strings


Example

The easiest way to create a multiline string is to just use multiple lines between quotation marks:

address = "Four score and seven years ago our fathers brought forth on this
continent, a new nation, conceived in Liberty, and dedicated to the
proposition that all men are created equal."

The main problem with that technique is that if the string includes a quotation, it'll break the string syntax. To work around the problem, you can use a heredoc instead:

puts <<-RAVEN
  Once upon a midnight dreary, while I pondered, weak and weary, 
  Over many a quaint and curious volume of forgotten lore— 
      While I nodded, nearly napping, suddenly there came a tapping, 
  As of some one gently rapping, rapping at my chamber door. 
  "'Tis some visitor," I muttered, "tapping at my chamber door— 
              Only this and nothing more." 
  RAVEN

Ruby supports shell-style here documents with <<EOT, but the terminating text must start the line. That screws up code indentation, so there's not a lot of reason to use that style. Unfortunately, the string will have indentations depending no how the code itself is indented.

Ruby 2.3 solves the problem by introducing <<~ which strips out excess leading spaces:

2.3
def build_email(address)
  return (<<~EMAIL)
    TO: #{address}

    To Whom It May Concern:

    Please stop playing the bagpipes at sunrise!
                     
    Regards,
    Your neighbor               
  EMAIL
end

Percent Strings also work to create multiline strings:

%q(
HAMLET        Do you see yonder cloud that's almost in shape of a camel?
POLONIUS        By the mass, and 'tis like a camel, indeed.
HAMLET        Methinks it is like a weasel.
POLONIUS        It is backed like a weasel.
HAMLET        Or like a whale?
POLONIUS        Very like a whale
)

There are a few ways to avoid interpolation and escape sequences:

  • Single quote instead of double quote: '\n is a carriage return.'

  • Lower case q in a percent string: %q[#{not-a-variable}]

  • Single quote the terminal string in a heredoc:

    <<-'CODE'
       puts 'Hello world!'
    CODE