Is there an easy way to do multiline indented strings in Ruby?

Question

Say I wanted to have a very large block of pretty printed html code strait inline with my ruby code. What is the cleanest way to do this without losing any formatting in my string or having to remember some sort of gsub regex.

Encoding it all in one line is easy to do but hard to read:

1.times do
  # Note that the spaces have been changed to _ so that they are easy to see here.
  doc = "\n<html>\n__<head>\n____<title>\n______Title\n____</title>\n__</head>\n__<body>\n____Body\n__</body>\n</html>\n"
  ans = "Your document: %s" % [doc]
  puts ans
end

Multiline text in ruby is easier to read but the string can't be indented with the rest of the code:

1.times do
  doc = "
<html>
  <head>
    <title>
      Title
    </title>
  </head>
  <body>
    Body
  </body>
</html>
"
  ans = "Your document: %s" % [doc]
  puts ans
end

For example the following is indented with my code, but the string now has four extra spaces in front of every line:

1.times do
  doc = <<-EOM

    <html>
      <head>
        <title>
          Title
        </title>
      </head>
      <body>
        Body
      </body>
    </html>
  EOM
  ans = "Your document: %s" % [doc]
  puts ans
end

Most people go with the HEREDOC code above, and do a regex replace on the result to take out the extra whitespace at the beginning of each line. I would like a way where I don't have to go through the trouble of regexing each time.

Check out - http://stackoverflow.com/questions/3350648/ruby-indented-multiline-strings — theglauber, Apr 05 '13 at 16:52
Also - http://stackoverflow.com/questions/3772864/how-do-i-remove-leading-whitespace-chars-from-ruby-heredoc — theglauber, Apr 05 '13 at 17:00
`I have a string ("when \n the\n clock\n strikes\n ten\n") that would be much cleaner if it can be typed in with actual newline characters.` doesn't make sense. `"\n"` are actual newline characters. — the Tin Man, Apr 05 '13 at 19:10
@theglauber I would like to use something off the shelf, and I don't want to memorize some regex. — Vanson Samuel, Apr 06 '13 at 18:26
@VansonSamuel Why would you need to memorize some regex? You could store it in a constant at the beginning of your code and use it through-out. I use a lot of regex in my code and I never memorize it. — Charles Caldwell, Apr 06 '13 at 23:27
@(Charles Caldwell) I find myself having to do this type of thing once in a while in different projects, and I figure it would be nice to have a standard way of doing this. — Vanson Samuel, Apr 07 '13 at 01:46

ens · Accepted Answer · 2017-11-30T18:19:42.597

Since Ruby 2.3, the <<~ heredoc strips leading content whitespace:

def make_doc(body)
  <<~EOF
  <html>
    <body>
      #{body}
    </body>
  </html>
  EOF
end

puts make_doc('hello')

For older Ruby versions, the following is more verbose than the solutions presented in the other answers, but there's almost no performance overhead. It's about as fast as a single long string literal:

def make_doc(body)
  "<html>\n"       \
  "  <body>\n"     \
  "    #{body}\n"  \
  "  </body>\n"    \
  "</html>"
end

Charles Caldwell · Answer 2 · 2013-04-05T16:47:11.670

20

string = %q{This
    is
        indented
  and
    has
         newlines}

Here is a blog with some examples of %q{}, %Q{} and others.

As far as having it easy to remember, think 'Q' for `Quotation Marks'.

Sidenote: Technically you don't need the 'q' while doing quotation.

string = %{This
   also
      is indented
  and
     has
   newlines
      and handles interpolation like 1 + 1 = #{1+1}
}

However, it is best practice and more readable to use %Q{}.

edited Apr 05 '13 at 16:47

answered Apr 05 '13 at 16:39

Charles Caldwell

16,649
4
40
47

1

`+1` for the blog link. :) – Arup Rakshit Apr 05 '13 at 17:43
I like %q{}, %Q{}, and %{}. However I want the string to be indented with my code. I rewrote my question so that it is clearer. – Vanson Samuel Apr 06 '13 at 18:31

Vanson Samuel · Answer 3 · 2013-04-06T18:38:53.407

5

The "|" in YAML allows you to create multiline strings that can be indented. The whitespace is only counted if it is in columns after the first non-whitespace character on the first line. In this way you can have multiline string that have indentation, but are also indented in the code.

require 'yaml'

1.times do
  doc = YAML::load(<<-EOM)
  |

     <html>
       <head>
         <title>
           Title
         </title>
       </head>
       <body>
         Body
       </body>
     </html>  
  EOM
  ans = "Your document: %s" % [doc]
  puts ans
end

edited Apr 06 '13 at 18:38

answered Apr 05 '13 at 16:30

Vanson Samuel

1,953
2
17
30

1

Why is this downvoted? heredocs are good for this sort of thing. – Jim Stewart Apr 05 '13 at 17:25
2

Because you don't need yaml to do it, you can just create a string with a HEREDOC – Jeff Paquette Apr 05 '13 at 18:11
I figured that was just a usage example, but fair enough; it should probably be edited to be more in the context of @VansonSamuel's question. – Jim Stewart Apr 06 '13 at 00:14
3

Yaml is important here, because it takes out the initial indentations. – Vanson Samuel May 18 '14 at 17:54
I like this, but this answer is cleaner http://stackoverflow.com/a/5638187/3319298 – Epigene Feb 26 '15 at 08:38

score 3 · Answer 4 · answered Apr 05 '13 at 19:19

It's not real obvious what you're asking for. If I wanted to generate strings like:

"when \n the\n clock\n strikes\n ten\n"

on the fly, I'd build them dynamically:

%w[when the clock strikes ten].join("\n ")
=> "when\n the\n clock\n strikes\n ten"

Concatenating a trailing "\n" will add the trailing carriage return:

%w[when the clock strikes ten].join("\n ") + "\n"
=> "when\n the\n clock\n strikes\n ten\n"

If I am dealing with sub-strings that have embedded spaces, I'd adjust the array to:

['when the', 'clock strikes', 'ten'].join("\n ") + "\n"
=> "when the\n clock strikes\n ten\n"

You are right the question was hard to understand. I rewrote it. Hopefully it's easier to understand now. — Vanson Samuel, Apr 06 '13 at 18:32

Is there an easy way to do multiline indented strings in Ruby?

4 Answers4