Metaprogramming Ruby 2

The Spells

Around Alias

Call the previous, aliased version of a method from a redefined method.

class String
  alias_method :old_reverse, :reverse

  def reverse
    "x#{old_reverse}x"
  end
end

"abc".reverse # => "xcbax"

For more information, see page Around Alias.

Blank Slate

Remove methods from an object to turn them into Ghost Methods (Ghost Method).

class C
  def method_missing(name, *args)
    "a Ghost Method"
  end
end

obj = C.new
obj.to_s # => "#<C:0x007fbb2a10d2f8>"

class D < BasicObject
  def method_missing(name, *args)
    "a Ghost Method"
  end
end

blank_slate = D.new
blank_slate.to_s # => "a Ghost Method"

For more information, see page Blank Slate.

Class Extension

Define ...