只有在行尾使用`rescue`才能捕获异常，但在使用`begin rescue`块时则不会

Question

我的声明失败了：

result = service.load_data()

现在以下抑制错误，然后我可以检查nil

result = service.load_data() rescue nil

但是当我执行以下操作时，初始错误会被抛到UI，我不会得到异常的details 。

begin
   result = service.load_data()
rescue => details         
   logger.fatal "Failed to load the data: #{details}"
end

我确信我必须缺少一个愚蠢的细节，但我似乎无法在这里发现问题。 那么为什么不调用rescue区？

更新：我得到的错误是这样的：

getaddrinfo: nodename nor servname provided, or not known

Answer 1

begin
   result = service.load_data()
rescue AnExceptionKlass => details    # here the name is SocketError    
   logger.fatal "Failed to load the data: #{details}"
end

使用上面的。

试图在这里复制错误，如下所示：

require 'net/http'
Net::HTTP.start('http://www.google.com') do |http|
response = http.get('/')
puts response
end
#=> getaddrinfo: No such host is known.  (SocketError)

修正如下：

require 'net/http'

begin

  htt = Net::HTTP.start('http://www.google.com')
  response = htt.get('/')
  puts response

rescue SocketError => details    # or the Exception class name may be SocketError    
   p "Failed to load the data: #{details}"
end

#=> "Failed to load the data: getaddrinfo: No such host is known. "