From: David Masover <ninja@...>
Date: 2011-01-12T12:27:34+09:00
Subject: Re: :: -- operator or not?

On Tuesday, January 11, 2011 05:16:24 pm Kedar Mhaswade wrote:
> The Pickaxe book calls it scope resolution "operator", whereas The Ruby
> Programming Language says it is not an operator because the righthand
> side is not a value or expression but an identifier (which I think I
> understand).
> 
> So, is :: an operator or not?

I would say no, because as far as I can tell, it can't be overloaded. Every 
other operator can be overloaded in some context. It would be kind of cool if 
it could -- for example, if the following worked:

class Decorated < BasicObject
  def initialize klass
    @klass = klass
  end
  def prettiness
    "I'm decorated!"
  end
  def method_missing name, *args, &block
    @klass.public_send name, *args, &block
  end
end

module Decorate
  def self.::(name)
    Decorated.new Object.const_get(name)
  end
end

Decorate::Integer.prettiness  # <== "I'm decorated!"

Of course, you can also do this kind of hack with const_missing. So I guess if 
:: is an operator, . is also, seeing as method_missing does the same thing. In 
any case, the above doesn't work at all -- and regardless, I don't actually 
have a use case beyond what people already hack with const_missing or 
Kernel#autoload.

It's a fine semantic difference, though -- I don't think it matters whether 
it's an operator or not.