Crystal得到了Exception的类

Question

我原以为typeof(...)会给我一个确切的类，但在抢救异常typeof(MyCustomException)时只返回Exception

class A < Exception; end
class B < A; end

begin
  raise B.new
rescue e
  puts typeof(e) # => Exception
end

puts typeof(B.new)按预期返回B

Answer 1

根据我在此处创建的问题的https://github.com/bararchy：https://github.com/crystal-lang/crystal/issues/4597

I think that typeof is indeed Exception, but .class will give you what you want , I could be mistaken but I think that is intended

所以是啊e.class返回B

Answer 2

rescue e不限制此救援块处理的异常类型。因此e可以是任何例外类型。

如果您只想处理B类型的异常，则应添加类型限制rescue e : B。然后，typeof(e)将为B。