localize a number (thousands and decimal separator)

Numeric_localize.rb

class Numeric

  # Localize a number, adding thousands and decimals separators and setting the
  # number of decimals
  #
  # @example
  #     1234.56.localize # => "1,234.56"
  #     1234.56.localize(thousands: "'", decimal: ",", places: 4) # => "1'234,5600"
  def localize(thousands: ',', decimal: '.', places: nil)
    raise ArgumentError, "decimal must be set" unless decimal
    raise ArgumentError, "thousands and decimal must be different" if thousands == decimal

    number            = places ? sprintf("%.*f", places, self) : to_s
    integer, decimals = *number.split(".")
    integer.gsub!(/(\d)(?=\d{3}+$)/, "\\1#{thousands}")

    decimals ? "#{integer}#{decimal}#{decimals}" : integer
  end
end