为什么rails强迫我使用bundle exec？

Question

我想使用“rake routes”运行我的 rake 命令

但是rails会产生以下错误

** Invoke routes (first_time)
** Invoke environment (first_time)
** Execute environment
rake aborted!
uninitialized constant ActiveAdmin
/Users/aaalsubaie/Sites/Posnegs/config/initializers/active_admin.rb:1
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/engine.rb:588
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/engine.rb:587:in `each'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/engine.rb:587
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/initializable.rb:30:in `instance_exec'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/initializable.rb:30:in `run'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/initializable.rb:55:in `run_initializers'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/initializable.rb:54:in `each'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/initializable.rb:54:in `run_initializers'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/application.rb:136:in `initialize!'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/railtie/configurable.rb:30:in `send'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/railtie/configurable.rb:30:in `method_missing'
/Users/aaalsubaie/Sites/Posnegs/config/environment.rb:5
/Library/Ruby/Site/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
/Library/Ruby/Site/1.8/rubygems/custom_require.rb:36:in `require'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/application.rb:103:in `require_environment!'
/Library/Ruby/Gems/1.8/gems/railties-3.2.3/lib/rails/application.rb:292:in `initialize_tasks'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:205:in `call'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:205:in `execute'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:200:in `each'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:200:in `execute'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:158:in `invoke_with_call_chain'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:151:in `invoke_with_call_chain'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:176:in `invoke_prerequisites'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:174:in `each'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:174:in `invoke_prerequisites'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:157:in `invoke_with_call_chain'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:151:in `invoke_with_call_chain'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/task.rb:144:in `invoke'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:116:in `invoke_task'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `top_level'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `each'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `top_level'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:88:in `top_level'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:66:in `run'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:63:in `run'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/bin/rake:33
/usr/bin/rake:23:in `load'
/usr/bin/rake:23
Tasks: TOP => routes => environment

奇怪的是当我运行“bundle exec rake routes”
它工作正常！我在开发/生产环境中遇到此错误

Answer 1

对特定版本的 gem 的依赖造成了先有鸡还是先有蛋的情况，即在应用发现它需要不同版本之前，可能会加载错误版本的 gem。 bundle exec 有助于从右脚下车。见http://yehudakatz.com/2011/05/30/gem-versioning-and-bundler-doing-it-right/

Answer 2

如果你使用 rvm，你可以使用bundle install --binstubs，然后你就不必再做 bundle exec 了。详情请见this post。

不要忘记将 bin 目录添加到您的 gitignore 文件中。