Heredocs are cool & useful - C++,D,Ruby,Python

String literal without need to escape backslash

config=<<'_'
{
    "key1": "{ \"key2\": \"123\"}"
}
_

squiggly heredoc (ruby 2.3)

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

squiggly heredoc remove indentation from the actual string.

data = JSON.parse(<<-DATA, symbolize_names: true)
page = <<-HTML
  Heredocs are cool & useful
HTML

-> "  Heredocs are cool & useful\n"

page = <<~HTML
  Heredocs are cool & useful
HTML

-> "Heredocs are cool & useful\n"

page = <<~HTML.strip
  Heredocs are cool & useful
HTML

-> "Heredocs are cool & useful"

Heredoc on next line

data = JSON.parse(<<-DATA, symbolize_names: true)
[
  {
    "id": "12345",
    "type": "New repository created",
    "repo": {
      "id": 3,
      "name": "yuki24/object_mapper"
    }
]
DATA

Alternate Syntax

As with most other literals, Ruby provides an alternate syntax for string literals. If you’re using a lot of quote characters inside your literals, for example, you may want to use this syntax. When you use this syntax is a matter of style, they’re usually not needed for strings.

Use the following sequence for single-quoted strings %q{ … }. Similarly, use the following syntax for double-quoted strings %Q{ … }.

You can use any characters you with instead of braces. If you use a brace, square bracket, angle bracket or parenthesis, then the matching character will end the literal. If you don’t want to use matching characters, you can use any other symbol (anything not a letter or number). The literal will be closed with another of the same symbol.

The alternate syntax also works as a multi-line string.

• No variable expension, no need to escape single quote

%q{#{no expension} single'quote}