gistfile1.rb

module Kernel
    def trace_instances(traced_class = ActiveRecord::Base, &block)
        instances = []
        set_trace_func(proc do |event, file, line, id, binding, classname|
            if event == "line"
                obj = eval("self", binding)
                instances << obj if obj.kind_of?(traced_class)
            end
        end)

        block.call
    ensure
        set_trace_func nil
        instances.uniq!

        puts "Traced instances: #{instances.size}"
        instances.each {|inst| puts "> #{inst.inspect}" }

        instances.clear
    end
end