Breaking up long strings on multiple lines in Ruby without stripping newlines

Maybe this is what you're looking for?

string = "line #1"\
         "line #2"\
         "line #3"

p string # => "line #1line #2line #3"

You can use \ to indicate that any line of Ruby continues on the next line. This works with strings too:

string = "this is a \
string that spans lines"

puts string.inspect

will output "this is a string that spans lines"

Three years later, there is now a solution in Ruby 2.3: The squiggly heredoc.

class Subscription
  def warning_message
    <<~HEREDOC
      Subscription expiring soon!
      Your free trial will expire in #{days_until_expiration} days.
      Please update your billing information.
    HEREDOC
  end
end

Blog post link: https://infinum.co/the-capsized-eight/articles/multiline-strings-ruby-2-3-0-the-squiggly-heredoc

The indentation of the least-indented line will be removed from each line of the content.

I had this problem when I try to write a very long url, the following works.

image_url = %w(
    http://minio.127.0.0.1.xip.io:9000/
    bucket29/docs/b7cfab0e-0119-452c-b262-1b78e3fccf38/
    28ed3774-b234-4de2-9a11-7d657707f79c?
    X-Amz-Algorithm=AWS4-HMAC-SHA256&
    X-Amz-Credential=ABABABABABABABABA
    %2Fus-east-1%2Fs3%2Faws4_request&
    X-Amz-Date=20170702T000940Z&
    X-Amz-Expires=3600&X-Amz-SignedHeaders=host&
    X-Amz-Signature=ABABABABABABABABABABAB
    ABABABABABABABABABABABABABABABABABABA
).join

Note, there must not be any newlines, white spaces when the url string is formed. If you want newlines, then use HEREDOC.

Here you have indentation for readability, ease of modification, without the fiddly quotes and backslashes on every line. The cost of joining the strings should be negligible.

I modified Zack's answer since I wanted spaces and interpolation but not newlines and used:

%W[
  It's a nice day "#{name}"
  for a walk!
].join(' ')

where name = 'fred' this produces It's a nice day "fred" for a walk!

This is by now a very old question but as the issue still seems to come up here's an updated answer. Since the original poster indicated this was for a Rails project you can look to Rails' String inflections for help.

my_long_string = <<-STRING
 hello
    there
 multiline
      multiindented string
STRING

=> " hello\n    there\n multiline\n      multiindented string\n"

Enter the squish method.

my_long_string = <<-STRING.squish
 so
    long
 multiline
      multiindented string
STRING

=> "so long multiline multiindented string"

As per the docs -

squish() Returns the string, first removing all whitespace on both ends of the string, and then changing remaining consecutive whitespace groups into one space each.

Squish in Rails is doing what you need.

https://apidock.com/rails/String/squish

End it looks like this:

%{ Multi-line
   string }.squish

And because you need it in Ruby, just look at Rails code:

%{ Multi-line
   string }
  .gsub!(/[[:space:]]+/, " ")
  .strip!

You can concatenate multiple strings split over several lines:

if foo
  string = "this is a" + 
           "string that spans lines"  
end