Complex number literal

Question

A complex number can be written as a literal like this:

3 + 2i # => (3+2i)

How is this syntactically distinguished from the case where receiver integer 3 receives the method + with argument 2i (which itself works as a literal for a complex number (0+2i))?

Answer 1

Short answer: it doesn't. The way it works is that the + method of integer receives the imaginary unit and returns a Complex. So in terms of literals you have the usual integer and floating point literals as well as imaginary number literal (e.g. 2i) and by combining them you can construct complex values.

Answer 2

I guess the documentation is misleading and what appears to be literal is really method call. I made an experiment that confirms this:

class Integer
  alias old_plus +

  def +(*args)
    puts 'called with complex' if args.first.class == Complex
    old_plus(*args)
  end
end

8+3i
# called with complex
# => (8+3i)
(9+2i)
# called with complex
# => (9+2i)