lib/decorate/before_decorator.rb

   1 require "decorate"
   2 require "decorate/create_alias"
   3
   4 # This module is highly experimental and might change significantly or
   5 # be removed completely since its usefulness is highly questionable in
   6 # its current form.
   7 module Decorate::BeforeDecorator
   8
   9   # Example:
  10   #
  11   #   require "decorate/before_decorator"
  12   #
  13   #   class Bf
  14   #     extend Decorate::BeforeDecorator
  15   #
  16   #     before_decorator :trace_call, :call => :trace_call
  17   #
  18   #     def trace_call(method_name, *args, &block)
  19   #       puts "Before #{self}.#{method_name}, args: #{args.inspect}, block: #{block.inspect}"
  20   #     end
  21   #
  22   #     def foo
  23   #       puts "foo"
  24   #     end
  25   #
  26   #     trace_call
  27   #     def bar
  28   #       puts "bar"
  29   #     end
  30   #
  31   #   end
  32   #
  33   #   >> o = Bf.new
  34   #   >> o.foo
  35   #   foo
  36   #   >> o.bar
  37   #   Before #<Bf:0xb7b32dbc>.bar, args: [], block: nil
  38   #   bar
  39   def before_decorator(decorator_name, opts) #:doc:
  40     before_method_name = opts[:call]
  41     unless before_method_name.kind_of?(Symbol)
  42       raise "Option :call with Symbol argument required"
  43     end
  44     unkown_opt = opts.keys.find { |opt| ![:call].include?(opt) }
  45     if unkown_opt
  46       raise "Unknown option #{unknown_opt.inspect}"
  47     end
  48
  49     self.class.send(:define_method, decorator_name) {
  50       Decorate.decorate { |klass, method_name|
  51         wrapped_method_name =
  52           Decorate.create_alias(klass, method_name, decorator_name)
  53         klass.class_eval <<-EOF, __FILE__, __LINE__
  54           def #{method_name}(*args, &block)
  55             self.__send__(:#{before_method_name},
  56                           :#{method_name}, *args, &block)
  57             self.__send__(:#{wrapped_method_name},
  58                           *args, &block)
  59           end
  60         EOF
  61       }
  62     }
  63   end
  64   private :before_decorator
  65
  66 end