如何在宝石中重新开设一堂课 [英] how to reopen a class in gems

问题描述

我在主应用程序中有相同的类，并且有一个gem（可挂载引擎）。
我想重新打开gem中的类（在主应用程序中定义）。




主应用程序有
app / models / test.rb

 class Test 
 def original_method 
 end 
 end 
 

in Gemfile

 
 gem'gem_name'
 

在宝石
中
app / models / test.rb

 
 class Test 
 def add_method 
 end 
 end 
 

但是，主应用程序产生了一个错误，就是Test＃original_method没有被定义。

它看起来像是Test class被覆盖在gem中。

为什么不重新打开？

我该如何解决问题？

编辑

  NoMethodError（未定义方法`original_method'for＃< Test：0x0000001997ca70>）：
 vendor / bundle / ruby​​ / 1.9.1 / gems /在'method_missing'
 vendor / bundle / ruby​​ / 1.9.1 / gems / activerecord-3.2.13 / lib / active_record / attribute_methods.rb中：activemodel-3.2.13 / lib / active_model / attribute_methods.rb：407： 149：在`method_missing'
 vendor / bundle / ruby​​ / 1.9.1 / bundler / gems / test_gem / app / controllers / tests_controller.rb：213：`new'
 vendor / 1.9.1 / gems / actionpack-3.2.13 / lib / action_controller / metal / implicit_render.rb：4：在`send_action'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / abstract_controller / base.rb：167：`process_action'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_controller / metal / rendering.rb：10： process_action'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / abstract_controller / callb acks.rb：18：在`block in process_action'
 vendor / bundle / ruby​​ / 1.9.1 / gems / activesupport-3.2.13 / lib / active_support / callbacks.rb：535：in'_run__422315203817736318__process_action__439125674649202736__callbacks'
 vendor / bundle / ruby​​ / 1.9.1 / gems / activesupport-3.2.13 / lib / active_support / callbacks.rb：405：在`__run_callback'
 vendor / bundle / ruby​​ / 1.9.1 / gems /在'_run_process_action_callbacks'
 vendor / bundle / ruby​​ / 1.9.1 / gems / activesupport-3.2.13 / lib / active_support / callbacks.rb中：activesupport-3.2.13 / lib / active_support / callbacks.rb：385： 81：在`run_callbacks'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / abstract_controller / callbacks.rb：17：在`process_action'
 vendor / bundle / ruby / 1.9.1 / gems / actionpack-3.2.13 / lib / action_controller / metal / rescue.rb：29：在`process_action'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2。 13 / lib / action_controller / metal / instrumentation.rb：30：在`block in process_action'
 vendor / bundle / ruby​​ / 1.9.1 / gems / activesupport-3中。 2.13 / lib / active_support / notifications.rb：123：在`block in instrument'中
 vendor / bundle / ruby​​ / 1.9.1 / gems / activesupport-3.2.13 / lib / active_support / notifications / instrumenter.rb： 20：在`instrument'中
 vendor / bundle / ruby​​ / 1.9.1 / gems / activesupport-3.2.13 / lib / active_support / notifications.rb：123：在`instrument'中
 vendor / bundle / ruby / 1.9.1 / gems / actionpack-3.2.13 / lib / action_controller / metal / instrumentation.rb：29：在`process_action'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2。 13 / lib / action_controller / metal / params_wrapper.rb：207：在`process_action'
 vendor / bundle / ruby​​ / 1.9.1 / gems / activerecord-3.2.13 / lib / active_record / railties / controller_runtime.rb： 18：在`process_action'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / abstract_controller / base.rb：121：in'process'
 vendor / bundle / ruby / 1.9.1 / gems / actionpack-3.2.13 / lib / abstract_controller / rendering.rb：45：在`process'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / LIB / action_controller /金属。 rb：203：在`dispatch'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_controller / metal / rack_delegation.rb：14：在`dispatch'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_controller / metal.rb：246：在`block in action'中
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpackage / route / set_rb：73：在`call'中
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / routing / route_set.rb：73：在`dispatch'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / routing / route_set.rb：36：in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / journey-1.0.4 / lib / journey / router.rb：68：在`block in call'中
 vendor / bundle / ruby​​ / 1.9.1 / gems / journey-1.0.4 / lib / journey / router.rb：56：在`each'
 vendor / bundle / ruby​​ / 1.9.1 / gems / journey-1.0.4 / lib / journey / router。 rb：56：在`call'中
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / routing / route_set.rb：612：在`call'中
供应商/束/ ruby / 1.9.1 / gems / warden-1.2.1 / lib / warden / manager.rb：35：在`block in call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / warden-1.2。 1 / lib / warden / manager.rb：34：在`catch'
 vendor / bundle / ruby​​ / 1.9.1 / gems / warden-1.2.1 / lib / warden / manager.rb：34：调用'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / best_standards_support.rb：17：'call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / rack-1.4.5 / lib / rack / etag.rb：23：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / rack-1.4.5 / lib / rack / conditionalget.rb：25：in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / head.rb：14：在`call' 
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / params_parser.rb：21：在`call'
 vendor / bundle / ruby​​ / 1.9。 1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / flash.rb：242：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / rack-1.4.5 / lib / rack / session / abstract / id.rb：210：在`context'
 vendor / bu ndle / ruby​​ / 1.9.1 / gems / rack-1.4.5 / lib / rack / session / abstract / id.rb：205：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / cookies.rb：341：在`call'中
 vendor / bundle / ruby​​ / 1.9.1 / gems / activerecord-3.2.13 / lib / active_record / query_cache。 rb：64：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / activerecord-3.2.13 / lib / active_record / connection_adapters / abstract / connection_pool.rb：479：in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / callbacks.rb：28：在`block in call'
 vendor / bundle / ruby​​ / 1.9。 1 / gems / activesupport-3.2.13 / lib / active_support / callbacks.rb：405：在_run__4226710667851682500__call__4227166089575601802__callbacks'
 vendor / bundle / ruby​​ / 1.9.1 / gems / activesupport-3.2.13 / lib / active_support / callbacks.rb：405：`__run_callback'
 vendor / bundle / ruby​​ / 1.9.1 / gems / activesupport-3.2.13 / lib / active_support / callbacks.rb：385：在_run_call_callbacks'
供应商/束/红宝石/ 1.9.1 /宝石/一ctivesupport-3.2.13 / lib / active_support / callbacks.rb：81：在`run_callbacks'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / callbacks。 rb：27：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / reloader.rb：65：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / remote_ip.rb：31：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack /中间件/ debug_exceptions.rb：16：在`call'中
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / show_exceptions.rb：56：`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / railties-3.2.13 / lib / rails / rack / logger.rb：32：在`call_app'
 vendor / bundle / ruby​​ / 1.9.1 / gems / railties-3.2.13 / lib / rails / rack / logger.rb：16：在`block in call'
 vendor / bundle / ruby​​ / 1.9。 1 / gems / activesupport-3.2.13 / lib / active_support / tagged_logging.rb：22：在`tagged'
 vendor / bundle / ruby​​ / 1.9.1 /gems/railties-3.2.13/lib/rails/rack/logger.rb:16:in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch /middleware/request_id.rb:22:in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / rack-1.4.5 / lib / rack / methodoverride.rb：21：in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / rack-1.4.5 / lib / rack / runtime.rb：17：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems /activesupport-3.2.13/lib/active_support/cache/strategy/local_cache.rb:72:in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / rack-1.4.5 / lib / rack /lock.rb:15:in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / actionpack-3.2.13 / lib / action_dispatch / middleware / static.rb：63：`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / railties-3.2.13 / lib / rails / engine.rb：479：in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems /railt/-3.2.13/lib/rails/application.rb:223:in`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / rack-1.4.5 / lib / rack / content_length.rb ：14：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / railties-3.2.13 / lib / rails / r ack / log_tailer.rb：17：在`call'
 vendor / bundle / ruby​​ / 1.9.1 / gems / rack-1.4.5 / lib / rack / handler / webrick.rb：59：在'service' 
 /usr/local/lib/ruby/1.9.1/webrick/httpserver.rb:138:in`service'
 /usr/local/lib/ruby/1.9.1/webrick/httpserver。 rb：94：'run'
 /usr/local/lib/ruby/1.9.1/webrick/server.rb:191:in`block in start_thread'
  
 
 
解决方案
试试
 $ c> Test.class_eval do 
 def original_method 
 end 
 end 
  

I have same class in main application and a gem (mountable engine).
I want to reopen the class(defined in main applicaion) in the gem.


Main application has
app/models/test.rb

class Test
  def original_method
  end
end

in Gemfile

gem 'gem_name'

In the gem
app/models/test.rb

class Test
  def add_method
  end
end

But main application raises an error that Test#original_method is not defined.
It looks like Test class is overwritten in the gem. Why not reopen?
How can I solve the problem??

EDIT

NoMethodError (undefined method `original_method' for #<Test:0x0000001997ca70>):
  vendor/bundle/ruby/1.9.1/gems/activemodel-3.2.13/lib/active_model/attribute_methods.rb:407:in `method_missing'
  vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/attribute_methods.rb:149:in `method_missing'
  vendor/bundle/ruby/1.9.1/bundler/gems/test_gem/app/controllers/tests_controller.rb:213:in `new'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_controller/metal/implicit_render.rb:4:in `send_action'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/abstract_controller/base.rb:167:in `process_action'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_controller/metal/rendering.rb:10:in `process_action'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/abstract_controller/callbacks.rb:18:in `block in process_action'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:535:in `_run__422315203817736318__process_action__439125674649202736__callbacks'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:405:in `__run_callback'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:81:in `run_callbacks'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/abstract_controller/callbacks.rb:17:in `process_action'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_controller/metal/rescue.rb:29:in `process_action'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in `block in instrument'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in `instrument'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_controller/metal/instrumentation.rb:29:in `process_action'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_controller/metal/params_wrapper.rb:207:in `process_action'
  vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/railties/controller_runtime.rb:18:in `process_action'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/abstract_controller/base.rb:121:in `process'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/abstract_controller/rendering.rb:45:in `process'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_controller/metal.rb:203:in `dispatch'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_controller/metal.rb:246:in `block in action'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:73:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:36:in `call'
  vendor/bundle/ruby/1.9.1/gems/journey-1.0.4/lib/journey/router.rb:68:in `block in call'
  vendor/bundle/ruby/1.9.1/gems/journey-1.0.4/lib/journey/router.rb:56:in `each'
  vendor/bundle/ruby/1.9.1/gems/journey-1.0.4/lib/journey/router.rb:56:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:612:in `call'
  vendor/bundle/ruby/1.9.1/gems/warden-1.2.1/lib/warden/manager.rb:35:in `block in call'
  vendor/bundle/ruby/1.9.1/gems/warden-1.2.1/lib/warden/manager.rb:34:in `catch'
  vendor/bundle/ruby/1.9.1/gems/warden-1.2.1/lib/warden/manager.rb:34:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
  vendor/bundle/ruby/1.9.1/gems/rack-1.4.5/lib/rack/etag.rb:23:in `call'
  vendor/bundle/ruby/1.9.1/gems/rack-1.4.5/lib/rack/conditionalget.rb:25:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/head.rb:14:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/params_parser.rb:21:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/flash.rb:242:in `call'
  vendor/bundle/ruby/1.9.1/gems/rack-1.4.5/lib/rack/session/abstract/id.rb:210:in `context'
  vendor/bundle/ruby/1.9.1/gems/rack-1.4.5/lib/rack/session/abstract/id.rb:205:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/cookies.rb:341:in `call'
  vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/query_cache.rb:64:in `call'
  vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:405:in `_run__4226710667851682500__call__4227166089575601802__callbacks'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:405:in `__run_callback'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:81:in `run_callbacks'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/reloader.rb:65:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
  vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/rack/logger.rb:32:in `call_app'
  vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/rack/logger.rb:16:in `block in call'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/tagged_logging.rb:22:in `tagged'
  vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/rack/logger.rb:16:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/request_id.rb:22:in `call'
  vendor/bundle/ruby/1.9.1/gems/rack-1.4.5/lib/rack/methodoverride.rb:21:in `call'
  vendor/bundle/ruby/1.9.1/gems/rack-1.4.5/lib/rack/runtime.rb:17:in `call'
  vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/cache/strategy/local_cache.rb:72:in `call'
  vendor/bundle/ruby/1.9.1/gems/rack-1.4.5/lib/rack/lock.rb:15:in `call'
  vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/static.rb:63:in `call'
  vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/engine.rb:479:in `call'
  vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/application.rb:223:in `call'
  vendor/bundle/ruby/1.9.1/gems/rack-1.4.5/lib/rack/content_length.rb:14:in `call'
  vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/rack/log_tailer.rb:17:in `call'
  vendor/bundle/ruby/1.9.1/gems/rack-1.4.5/lib/rack/handler/webrick.rb:59:in `service'
  /usr/local/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
  /usr/local/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
  /usr/local/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'

解决方案

try

Test.class_eval do
  def original_method
  end
end

这篇关于如何在宝石中重新开设一堂课的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！