Contents

#!/usr/bin/env ruby
# Example demonstrating "around" advice for method_missing. This is a 
# technique for avoiding collisions when different toolkits want to override
# method_missing in the same classes, e.g., Object. Using around advice as 
# shown allows a toolkit to add custom behavior while invoking the "native" 
# method_missing to handle unrecognized method calls.
# Note that it is essential to use around advice, not before or after advice,
# because neither can prevent the call to the "wrapped" method_missing, which
# is presumably not what you want. In this (contrived) example, an Echo class
# uses method_missing to simply echo the method name and arguments. An aspect
# is used to intercept any calls to a fictitious "log" method and handle those
# in a different way.

$LOAD_PATH.unshift File.dirname(__FILE__) + '/../lib'
require 'aquarium'

module Aquarium
  class Echo
    def method_missing sym, *args
      p "Echoing: #{sym.to_s}: #{args.join(" ")}"
    end
    def respond_to? sym, include_private = false
      true
    end
  end
end

p "Before advising Echo:"
echo1 = Aquarium::Echo.new
echo1.say "hello", "world!"
echo1.log "something", "interesting..."
echo1.shout "theater", "in", "a", "crowded", "firehouse!"

Aquarium::Aspects::Aspect.new :around, 
    :calls_to => :method_missing, 
    :for_type => Aquarium::Echo do |jp, obj, sym, *args|
  if sym == :log 
    p "--- Sending to log: #{args.join(" ")}" 
  else
    jp.proceed
  end
end

p "After advising Echo:"
echo2 = Aquarium::Echo.new
echo2.say "hello", "world!"
echo2.log "something", "interesting..."
echo2.shout "theater", "in", "a", "crowded", "firehouse!"

Version data entries

4 entries across 4 versions & 1 rubygems

Version	Path
aquarium-0.7.3	examples/method_missing_example.rb
aquarium-0.7.1	examples/method_missing_example.rb
aquarium-0.5.1	examples/method_missing_example.rb
aquarium-0.4.4	examples/method_missing_example.rb