Re: Will be gone and Will have been gone.
Please note my corrections above.
Originally Posted by swety
"When I will come" is an old-fashioned style of expression, that is not used nowadays. "When I come" is more normal.
"When I come, you will be gone" means exactly what it says, and stands alone.
"When I come, you will have been gone" does not make sense without adding something on about how long you will have been gone, eg "When I come, you will have been gone for several days".
I'm not a teacher of English, but I have spoken it for (almost) all of my life....