gistfile1.rb

module BlackMagick
  def keys &block
    define_method :keys, &block
  end
end

class LeThing
  extend BlackMagick
end

klass = Class.new(LeThing) do |c|
  keys do
    ['name','date','magic']
  end
end

#klass.keys => ['name','date','magic']

#Instead I get 'ArgumentError, tried to create Proc object without a block'