如何在Ruby on Rails的IRB中停止加载脚本的执行是最佳方法？

Question

寻找在Ruby on Rails的IRB中退出已加载脚本的最佳方法。Kernel.exit和Kernel.abort会完全弹出IRB会话。理想情况下，这应该在某些条件下发生。

我的脚本/my_script.rb：

puts "My Script is running!"
# if some criteria, stop execution of this script without stoping IRB
puts "This will never happen"

理想的结果：

$ rails console
irb(main):001:0> load 'script/my_script.rb'
My Script is running!
irb(main):002:0>

- spyle

Answer 1

使用__END__关键字停止解析器。

puts "My Script is running!"
__END__
puts "This will never happen"
...

或者您可以将脚本的其余部分注释掉（如果您需要在 ___END__ 之后得到一个格式良好的 DATA 流）。

puts "My Script is running!"
=begin
puts "This will never happen"
...
=end

如果您需要根据逻辑而不是在固定点上提前退出，您可以将脚本的主体放入一个函数中并尽早返回。

def do_work
  puts "My Script is running!"
  ...
  return if exit_condition?
  puts "This will never happen if exit condition is true"
  ...
end

do_work

或者，将您的脚本放在begin块中，并捕获您引发的异常

begin
  puts "My Script is running!"
  raise SystemExit if exit_condition?
  puts "This will never happen if exit condition is true"
rescue SystemExit
end

- dbenhur

---

基于原始问题的有效答案。如果需要有条件地退出，则无法工作。（我已更新帖子以包括条件要求。） - spyle

@spyle 正在处理那个问题，详见更新。 - dbenhur

Answer 2

我目前能想到的最好解决方案是引发一个脚本未处理的异常。然而，这会输出堆栈跟踪信息，可能是不希望看到的。

script/my_script.rb

puts "My Script is running!"
raise "quiting, but I'm not happy about it"
puts "This will never happen"

结果：

irb(main):001:0> load 'script/my_script.rb'
My Script is running!
RuntimeError: quiting, but I'm not happy about it
    from script/my_script.rb:2:in `<top (required)>'
    from /usr/local/rbenv/versions/1.9.3-p374/lib/ruby/gems/1.9.1/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:245:in `load'
    from /usr/local/rbenv/versions/1.9.3-p374/lib/ruby/gems/1.9.1/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:245:in `block in load'
    from /usr/local/rbenv/versions/1.9.3-p374/lib/ruby/gems/1.9.1/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:236:in `load_dependency'
    from /usr/local/rbenv/versions/1.9.3-p374/lib/ruby/gems/1.9.1/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:245:in `load'
    from (irb):1
    from /usr/local/rbenv/versions/1.9.3-p374/lib/ruby/gems/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:47:in `start'
    from /usr/local/rbenv/versions/1.9.3-p374/lib/ruby/gems/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:8:in `start'
    from /usr/local/rbenv/versions/1.9.3-p374/lib/ruby/gems/1.9.1/gems/railties-3.2.13/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'
irb(main):002:0>

- spyle

---

你可以触发异常，然后捕获它并什么也不做。 - Wally Altman