ruby-on-rails - 在 Rails 中使用 gem 时， 'cannot remove Object::ClassMethods' 源于什么？

Question

我在安装 gem 时经常遇到问题，例如:

有谁知道这源于什么？我已经在其中看到了几种不同的情况，但仍然没有了解究竟是什么原因造成的。

$ sudo rake gems:install --trace
(in /u/app/releases/20100213003957)
** Invoke gems:install (first_time)
** Invoke gems:base (first_time)
** Execute gems:base
** Invoke environment (first_time)
** Execute environment
rake aborted!
cannot remove Object::ClassMethods
/u/app/releases/20100213003957/vendor/rails/activesupport/lib/active_support/dependencies.rb:603:in `remove_const'
/u/app/releases/20100213003957/vendor/rails/activesupport/lib/active_support/dependencies.rb:603:in `remove_constant'
/u/app/releases/20100213003957/vendor/rails/activesupport/lib/active_support/dependencies.rb:603:in `instance_eval'
/u/app/releases/20100213003957/vendor/rails/activesupport/lib/active_support/dependencies.rb:603:in `remove_constant'
/u/app/releases/20100213003957/vendor/rails/activesupport/lib/active_support/dependencies.rb:549:in `new_constants_in'
/u/app/releases/20100213003957/vendor/rails/activesupport/lib/active_support/dependencies.rb:549:in `each'
/u/app/releases/20100213003957/vendor/rails/activesupport/lib/active_support/dependencies.rb:549:in `new_constants_in'
/u/app/releases/20100213003957/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
/u/app/releases/20100213003957/vendor/rails/railties/lib/tasks/misc.rake:4
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:617:in `call'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:617:in `execute'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:612:in `each'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:612:in `execute'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:578:in `invoke_with_call_chain'
/usr/lib64/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:571:in `invoke_with_call_chain'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:564:in `invoke'
/u/app/releases/20100213003957/vendor/rails/railties/lib/tasks/gems.rake:17
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:617:in `call'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:617:in `execute'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:612:in `each'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:612:in `execute'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:578:in `invoke_with_call_chain'
/usr/lib64/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:571:in `invoke_with_call_chain'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:588:in `invoke_prerequisites'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:585:in `each'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:585:in `invoke_prerequisites'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:577:in `invoke_with_call_chain'
/usr/lib64/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:571:in `invoke_with_call_chain'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:564:in `invoke'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2027:in `invoke_task'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2005:in `top_level'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2005:in `each'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2005:in `top_level'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2044:in `standard_exception_handling'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:1999:in `top_level'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:1977:in `run'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:2044:in `standard_exception_handling'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/lib/rake.rb:1974:in `run'
/usr/lib64/ruby/gems/1.8/gems/rake-0.8.4/bin/rake:31
/usr/bin/rake:19:in `load'
/usr/bin/rake:19

Answer 1

我相信我已经找到了一种实用的非侵入性方法来解决问题的根源。它对我有用(Rails 2.3):

碰巧异常(exception)#blame_file!尽管它会失败并导致新的错误，但在某些时候调用它，从而掩盖了原始错误。

因此，打开您的 FIRST 初始化程序并添加，

class Exception
  def blame_file!( file )
    puts "CULPRIT >> '#{file.to_s}' # #{self.to_s}"
  end
end

您将获得被指控的文件和原始错误消息。这应该足以查明您的问题。

不要忘记删除异常初始化程序片段。