_在ruby里是什么类型？

Question

小弟好奇_在ruby中是什么class，便做了个实验，打开irb，输入_.class返回的是NilClass，再输入一次_.class返回的就是Class了，这是为什么?

我的版本是irb 0.95，ruby 1.87

Answer 1

After testing, I found that "_" should save the content of the last standard output of irb. Of course, since it is standard output, it does not include exception information.