Class: Module

Inherits:
Object
  • Object
show all
Defined in:
lib/monkey_patch.rb

Instance Method Summary collapse

Instance Method Details

#delegate(*methods) ⇒ Object

Delegate method It expects an array of arguments that contains the methods to be delegated and a hash of options



37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
 
# File 'lib/monkey_patch.rb', line 37

def delegate(*methods)
  # Pop up the options hash from arguments array
  options = methods.pop
  # Check the availability of the options hash
  # and more specifically the :to option
  # Raises an error if one of them is not there
  unless options.is_a?(Hash) && to = options[:to]
    raise ArgumentError, "Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, :to => :greeter)."
  end

  # Make sure the :to option follows syntax rules
  # for method names
  if options[:prefix] == true && options[:to].to_s =~ /^[^a-z_]/
    raise ArgumentError, "Can only automatically set the delegation prefix when delegating to a method."
  end

  # Set the real prefix value
  prefix = options[:prefix] && "#{options[:prefix] == true ? to : options[:prefix]}_"

  # Here comes the magic of ruby :)
  # Reflection techniques are used here:
  # module_eval is used to add new methods on the fly which:
  # expose the contained methods' objects
  methods.each do |method|
    module_eval("def #{prefix}#{method}(*args, &block)\n#{to}.__send__(#{method.inspect}, *args, &block)\nend\n", "(__DELEGATION__)", 1)
  end
end