在以ENV结尾的Rails应用中，猴子修补ENV不是一个类（TypeError）

Question

我正在尝试向Rails 4应用程序的ENV类添加一些功能。

我在config/initializers/env_extend.rb如下所示：

class ENV
  def self.enabled?(env_key)
    if ENV[env_key].nil?
      return false
    else
      return ActiveRecord::ConnectionAdapters::Column::TRUE_VALUES.include?(ENV[env_key])
    end
  end
end

但是，当我使用rails console加载应用程序时，它不会加载，并且打印出以下内容

[mveksler:...web/lib/core_extensions/ENV]$ cd ~/Developer/referral-web
/Users/mveksler/Developer/referral-web/config/initializers/env_extend.rb:1:in `<top (required)>': ENV is not a class (TypeError)
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:268:in `load'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:268:in `block in load'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240:in `load_dependency'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:268:in `load'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/engine.rb:652:in `block in load_config_initializer'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/notifications.rb:166:in `instrument'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/engine.rb:651:in `load_config_initializer'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/engine.rb:616:in `block (2 levels) in <class:Engine>'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/engine.rb:615:in `each'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/engine.rb:615:in `block in <class:Engine>'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/initializable.rb:30:in `instance_exec'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/initializable.rb:30:in `run'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/initializable.rb:55:in `block in run_initializers'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:228:in `block in tsort_each'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:422:in `block (2 levels) in each_strongly_connected_component_from'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:422:in `block (2 levels) in each_strongly_connected_component_from'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:431:in `each_strongly_connected_component_from'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:421:in `block in each_strongly_connected_component_from'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/initializable.rb:44:in `each'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/initializable.rb:44:in `tsort_each_child'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:415:in `call'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:415:in `each_strongly_connected_component_from'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:421:in `block in each_strongly_connected_component_from'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/initializable.rb:44:in `each'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/initializable.rb:44:in `tsort_each_child'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:415:in `call'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:415:in `each_strongly_connected_component_from'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:349:in `block in each_strongly_connected_component'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:347:in `each'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:347:in `call'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:347:in `each_strongly_connected_component'%
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:226:in `tsort_each'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/tsort.rb:205:in `tsort_each'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/initializable.rb:54:in `run_initializers'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-4.2.6/lib/rails/application.rb:352:in `initialize!'
    from /Users/mveksler/Developer/referral-web/config/environment.rb:5:in `<top (required)>'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `block in require'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240:in `load_dependency'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-1.7.1/lib/spring/application.rb:92:in `preload'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-1.7.1/lib/spring/application.rb:143:in `serve'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-1.7.1/lib/spring/application.rb:131:in `block in run'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-1.7.1/lib/spring/application.rb:125:in `loop'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-1.7.1/lib/spring/application.rb:125:in `run'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/spring-1.7.1/lib/spring/application/boot.rb:19:in `<top (required)>'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
    from /Users/mveksler/.rbenv/versions/2.3.1/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
    from -e:1:in `<main>'

这可能是什么原因？

Answer 1

ENV不是一个类（或模块），它是一个常量。 这应该工作

  def ENV.enabled?(env_key)
    if ENV[env_key].nil?
      return false
    else
      return ActiveRecord::ConnectionAdapters::Column::TRUE_VALUES.include?(ENV[env_key])
    end
  end

但我不确定您要达到什么目标。 您只是想致电.enabled? 在ENV

编辑：我应该补充一点，类和模块也是常量，但我的观点是，它不是类或模块。