Question

I would like to achieve the following by introducing a new operator (e.g. :=)

a := b = {}
b[1] = 2
p a # => {}
p b # => {1=>2}

As far as I understand, I need to modify the Object class, but I don’t know what to do in order to get what I want.

require 'superators'
class Object
  superator ":=" operand # update, must be: superator ":=" do |operand|
    # self = Marshal.load(Marshal.dump(operand)) # ???
  end
end

Could you help me with this?

---

Update

Ok, superators will probably not help me here, but I still want such operator. How can I (or you) create an extension for Ruby, which I could load as a module?

require 'deep_copy_operator'
a !?= b = {} # I would prefer ":=" but don't really care how it is spelled
b[1] = 2
p a # => {}
p b # => {1=>2}

Answer 1

First of all, the syntax for superators is

superator ":=" do |operand|
  #code
end

It’s a block, because superator is a metaprogramming macro.

Secondly, you have something going their with Marshal…but it’s a bit of magic-ish. Feel free to use it as long as you understand exactly what it is you’re doing.

Thirdly, what you are doing isn’t quite doable with a superator (I believe), because self cannot be modified during a function. (if someone knows otherwise, please let me know)

Also, in your example, a must first exist and be defined before being able to call the method := in it.

Your best bet is probably:

class Object
  def deep_clone
    Marshal::load(Marshal.dump(self))
  end
end

to generate a deep clone of an object.

a = (b = {}).deep_clone
b[1] = 2
p a # => {}
p b # => {1=>2}