String#after.rb

class String
  # Return everything after the given string
  # or nil if the substring can't be found 
  def after(prefix)
    match = self.match Regexp.new(Regexp.escape(prefix) + "(.*)")
    match && match[1]
  end
end

dir = "/Users/mat/Desktop/wordpress-1"
#=> "/Users/mat/Desktop/wordpress-1"

file = "/Users/mat/Desktop/wordpress-1/wp-trackback.php"
#=> "/Users/mat/Desktop/wordpress-1/wp-trackback.php"

file.after dir
#=> "/wp-trackback.php"

file.after "uhh"
#=> nil