Probe into all instance method calls for a given class

probe.rb

# will look into all method call in instances of given class
module Probe
  def self.instances(klass, opts = {})
    methods = if opts.is_a?(Array)
                opts
              else
                methods_list(klass, opts)
              end

    methods.uniq.each do |m|
      method = klass.instance_method(m)

      if klass.included_modules.include?(method.owner)
        probe_instance_module_method(klass, method.owner, m)
      elsif klass == method.owner
        probe_instance_method(klass, m)
      else
        raise "Don't know what to do with #{m}"
      end
    end
  end

  def self.methods_list(klass, opts)
    klass.instance_methods(false)
  end

  def self.probe_instance_module_method(klass, modulez, method)
    on_class(klass) do
      <<EOD
      def #{method}(*args)
        Probe.register("#{klass.name}", :#{method}, args)
        m = #{modulez.name}.instance_method(:#{method})
        m.bind(self)
        m.call(*args)
      end
EOD
    end
  end

  def self.probe_instance_method(klass, method)
    aliaz = alias_method_name(method)

    on_class(klass) do
      <<EOD
      alias :#{aliaz} :#{method}

      def #{method}(*args)
        Probe.register("#{klass.name}", :#{method}, args)
        send(:#{aliaz}, *args)
      end
EOD
    end
  end

  def self.on_class(klass, &block)
    eval <<EOD
    class #{klass.name}
      #{block.call}
    end
EOD
  end

  def self.alias_method_name(method_name)
    "__" << method_name.to_s.gsub(/\?/, "_q").gsub(/\!/, "_bang").gsub(/\=/, "_eql") << "_original"
  end

  def self.register(kn, m, args = [])
    puts "-> #{kn}##{m}(#{args.join(", ")})"
    self.mem ||= []
    self.mem << [kn, m, args]
  end

  mattr_accessor :mem
end