unexpected return (LocalJumpError) only when executing this code within autoloaded classes?

Posted on stackoverflow but no traction yet:
http://stackoverflow.com/questions/12942505/why-does-using-set-trace-func-work-in-some-places-but-cause-unexpected-return-l

The following is a generified part of the code in a gem I’m working on:

module SomeModule
  class << self
    attr_accessor :procedure

    def log_events(*args)
      args.flatten!
      if args.size == 1
        eval "set_trace_func proc {|event, file, line, id, binding, classname| begin; SomeModule.procedure.call(event, file, line, id, binding, classname) if event == #{args[0].inspect}; rescue SystemExit, Interrupt; raise; rescue Exception; end}"
      elsif args.size > 1
        eval "set_trace_func proc {|event, file, line, id, binding, classname| begin; SomeModule.procedure.call(event, file, line, id, binding, classname) if #{args.inspect}.include?(event); rescue SystemExit, Interrupt; raise; rescue Exception; end}"
      else
        # ...
      end
    end
  end
end

SomeModule.procedure = lambda {|event, file, line, id, binding, classname| puts "#{event} #{file}.#{line} #{binding} #{classname} #{id}"}

When I then call:

SomeModule.log_events 'call', 'return'

just before the configure block in my Rails app’s config/environments/development.rb, it works fine and continues to work.

But, when I call it in app/controllers/application_controller.rb above or below the class definition, Rails dies during autoloading in activesupport-3.2.8/lib/active_support/dependencies.rb:469 due to an unexpected return (LocalJumpError).

Here is the log:

return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/initializable.rb.30 #<Binding:0x007ff7b1403d40> Rails::Initializable::Initializer run
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/initializable.rb.54 #<Binding:0x007ff7b14039a8> Rails::Initializable run_initializers
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/application.rb.136 #<Binding:0x007ff7b1403728> Rails::Application initialize!
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/railtie/configurable.rb.30 #<Binding:0x007ff7b1403480> Rails::Railtie::Configurable::ClassMethods method_missing
call /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb.275 #<Binding:0x007ff7b1402aa8> ActiveSupport::Dependencies::Blamable blame_file!
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb.277 #<Binding:0x007ff7b1402440> ActiveSupport::Dependencies::Blamable blame_file!
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb.233 #<Binding:0x007ff7b1401a40> ActiveSupport::Dependencies::Loadable load_dependency
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb.251 #<Binding:0x007ff7b1409790> ActiveSupport::Dependencies::Loadable require
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/builder.rb.51 #<Binding:0x007ff7b14093f8> Rack::Builder initialize
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/builder.rb.40 #<Binding:0x007ff7b1408ac0> Rack::Builder parse_file
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/server.rb.200 #<Binding:0x007ff7b1408840> Rack::Server app
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/commands/server.rb.46 #<Binding:0x007ff7b1408598> Rails::Server app
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/server.rb.301 #<Binding:0x007ff7b14082f0> Rack::Server wrapped_app
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/server.rb.252 #<Binding:0x007ff7b1408048> Rack::Server start
call /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/server.rb.179 #<Binding:0x007ff7b1407c88> Rack::Server options
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/server.rb.181 #<Binding:0x007ff7b14078f0> Rack::Server options
Exiting
return /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/commands/server.rb.74 #<Binding:0x007ff7b1406ec8> Rails::Server start
/path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:469:in `load': unexpected return (LocalJumpError)
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:469:in `block in load_file'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:639:in `new_constants_in'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:468:in `load_file'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:353:in `require_or_load'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:502:in `load_missing_constant'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:192:in `block in const_missing'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:190:in `each'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:190:in `const_missing'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/base_controller/menu.rb:2:in `<module:ActiveAdmin>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/base_controller/menu.rb:1:in `<top (required)>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `block in require'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:236:in `load_dependency'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/base_controller.rb:2:in `<top (required)>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/resource_controller/actions.rb:2:in `<module:ActiveAdmin>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/resource_controller/actions.rb:1:in `<top (required)>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `block in require'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:236:in `load_dependency'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/resource_controller.rb:2:in `<top (required)>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/batch_actions.rb:7:in `block in <top (required)>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/event.rb:25:in `call'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/event.rb:25:in `block in dispatch'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/event.rb:24:in `each'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/event.rb:24:in `dispatch'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/application.rb:179:in `load!'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/application.rb:205:in `routes'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin.rb:79:in `routes'
  from /path/to/git/some_app_gemset/config/routes.rb:2:in `block in <top (required)>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/actionpack-3.2.8/lib/action_dispatch/routing/route_set.rb:282:in `instance_exec'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/actionpack-3.2.8/lib/action_dispatch/routing/route_set.rb:282:in `eval_block'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/actionpack-3.2.8/lib/action_dispatch/routing/route_set.rb:260:in `draw'
  from /path/to/git/some_app_gemset/config/routes.rb:1:in `<top (required)>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:245:in `load'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:245:in `block in load'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:236:in `load_dependency'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:245:in `load'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/application/routes_reloader.rb:40:in `each'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/application/routes_reloader.rb:40:in `load_paths'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/application/routes_reloader.rb:16:in `reload!'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/application.rb:108:in `reload_routes!'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/reloader.rb:34:in `reload!'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activeadmin-0.5.0/lib/active_admin/reloader.rb:61:in `block in attach!'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/callbacks.rb:429:in `_run__1105766863370890952__prepare__156232144867029268__callbacks'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/callbacks.rb:405:in `__run_callback'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/callbacks.rb:385:in `_run_prepare_callbacks'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/callbacks.rb:81:in `run_callbacks'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/actionpack-3.2.8/lib/action_dispatch/middleware/reloader.rb:74:in `prepare!'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/actionpack-3.2.8/lib/action_dispatch/middleware/reloader.rb:48:in `prepare!'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/application/finisher.rb:47:in `block in <module:Finisher>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/initializable.rb:30:in `instance_exec'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/initializable.rb:30:in `run'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/initializable.rb:55:in `block in run_initializers'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/initializable.rb:54:in `each'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/initializable.rb:54:in `run_initializers'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/application.rb:136:in `initialize!'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/railtie/configurable.rb:30:in `method_missing'
  from /path/to/git/some_app_gemset/config/environment.rb:5:in `<top (required)>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `block in require'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:236:in `load_dependency'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
  from /path/to/git/some_app_gemset/config.ru:4:in `block in <main>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/builder.rb:51:in `instance_eval'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/builder.rb:51:in `initialize'
  from /path/to/git/some_app_gemset/config.ru:1:in `new'
  from /path/to/git/some_app_gemset/config.ru:1:in `<main>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/builder.rb:40:in `eval'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/builder.rb:40:in `parse_file'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/server.rb:200:in `app'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/commands/server.rb:46:in `app'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/server.rb:301:in `wrapped_app'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/rack-1.4.1/lib/rack/server.rb:252:in `start'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/commands/server.rb:70:in `start'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/commands.rb:55:in `block in <top (required)>'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/commands.rb:50:in `tap'
  from /path/to/.rvm/gems/ruby-1.9.3-p194@some_app_gemset/gems/railties-3.2.8/lib/rails/commands.rb:50:in `<top (required)>'
  from script/rails:6:in `require'
  from script/rails:6:in `<main>'

Any idea what I’m doing wrong, or how to determine when and where this type of usage of set_trace_func should work?