当引发异常并且程序停止执行时，哪个系统信号被发送到 ruby 程序

Question

每当我的程序停止执行时（无论是在被cmd-c关闭时还是遇到异常时），我都想采取一些操作来正确关闭。

当我做cmd-c时，我收到信号TERM。当程序遇到引发的异常时，会发送什么信号？如何使用 Signal.trap（...） 捕获它？

Answer 1

您可以将

代码包装在begin-ensure-end块中。它将捕获异常和 CTRL-C。（您可以在ensure之前添加救援条款）。

begin
  sleep 10 #try CTRL-C here
  raise "kaboom" #RuntimeError
ensure
  puts "This must be printed no matter what."
end

Answer 2

异常不是信号。 Ruby 解释器处理用户代码中的所有异常;没有什么可困住的。

如果要处理异常，则需要在rescue块中执行此操作。

Answer 3

您无法将异常捕获为信号，但您可以在使用 'EXIT' 信号引发异常时执行某些操作：

Signal.trap('EXIT') do
  puts "Terminating..."
  shutdown()
end

但是，我只是说你可以这样做;你真的应该使用begin和rescue。

Answer 4

点机智的异常不是通过Signal.trap捕获信号，而是将可能引发异常的代码包装在begin-rescue-end块中。不过，您还有更多选择：

begin
  # here goes the code that may raise an exception
rescue ThisError
  # this code is executed when 'ThisError' was raised
rescue ThatError, AnotherError
  # this code is executed when 'ThatError' or 'AnotherError' was raised
rescue
  # this code is executed when any other StandardError was raised
else
  # this code is executed when NO exception was raised
ensure
  # this code is always executed
end

以下是如何使用它的一些更实际的示例：

def compute_something(x,y)
  raise ArgumentError, 'x must not be lower than 0' if x < 0
  x/y + y
end
begin
  compute_something(-10,5)
rescue ArgumentError
  puts "some argument is erroneous!"
end
puts "---"
x=100
y=0
begin
  compute_something(x,y)
rescue ZeroDivisionError
  puts "division by zero! trying to fix that..."
  y=1
  retry
else
  puts "everything fine!"
end
puts "---"
begin
  compute_something(1)
rescue => e
  puts "the following error occured:"
  puts e
end
puts "---"
begin
  exit
ensure
  puts "i am always called!"
end

这将输出：

some argument is erroneous!
---
division by zero! trying to fix that...
everything fine!
---
the following error occured:
wrong number of arguments (1 for 2)
---
i am always called!

Answer 5

作为上述解决方案的替代方法，您可以研究at_exit方法。