This

Ruby should be able to have fun with private writer methods.  That is what This is.

@chadfowler posted this ruby quiz on twitter on Mar 31, 2009:

Ruby quiz: in 140 chrs or less, why doesn't this work:
class Y; def a; self.x end; private; def x; puts "hi" end end; Y.new.a
(http://twitter.com/chadfowler/status/11390678834)

With whitespace:

  class Y
    def a
      self.x
    end

    private
    def x
      puts "hi"
    end
  end
  
  Y.new.a

results in:

  NoMethodError: private method `x' called for #<Y:0x10f6af8>
  from (irb):1:in `a'
  from (irb):1

You get a NoMethodError because you can't call a private method on self.
Ruby doesn't check the caller when sending messages to the 'self' receiver,
so privacy reigns.

With This, we get:

  require 'this'
  include This

  class Y
    def a
      this.x
    end

    private
    def x
      puts "hi"
    end
  end
  
  Y.new.a

  hi
  => nil

Ahhh...


Copyright 2010 Ryan Angilly