Percent Literals

  • Prefer parentheses over curly
    braces, brackets, or pipes when using %-literal delimiters for
    consistency, and because the behavior of %-literals is closer to method
    calls than the alternatives.[link]

    1.   # bad
    2.   %w[date locale]
    3.   %w{date locale}
    4.   %w|date locale|
    6.   # good
    7.   %w(date locale)

  • Use %w freely.[link]

    1.   STATES = %w(draft open closed)

  • Use %() for single-line strings which require
    both interpolation and embedded double-quotes. For multi-line strings,
    prefer heredocs.[link]

    1.   # bad - no interpolation needed
    2.   %(Welcome, Jane!)
    3.   # should be 'Welcome, Jane!'
    5.   # bad - no double-quotes
    6.   %(This is #{quality} style)
    7.   # should be "This is #{quality} style"
    9.   # bad - multiple lines
    10.   %(Welcome, Jane!\nPlease enjoy your stay at #{location}\nCheers!)
    11.   # should be a heredoc.
    13.   # good - requires interpolation, has quotes, single line
    14.   %(Welcome, #{name}!)

  • Use %r only for regular expressions matching more
    than     one ‘/‘ character.[link]

    1.   # bad
    2.   %r(\s+)
    4.   # still bad
    5.   %r(^/(.*)$)
    6.   # should be /^\/(.*)$/
    8.   # good
    9.   %r(^/blog/2011/(.*)$)

  • Avoid the use of %x unless you’re going to invoke a
    command with backquotes in it (which is rather unlikely).
    [link]

    1.   # bad
    2.   date = %x(date)
    4.   # good
    5.   date = `date`
    6.   echo = %x(echo `date`)