How to set manually the alternate file

Question

Reading the documentation about alternate file, I thought I could manipulate # like a global variable, but it's not the case. I was thinking doing something like

let &#='/path/to/alternate/file'

Which is not possible.

How would you set manually the alternate file?

Answer 1

The alternate file is stored in a register, "#. Change you line to:

let @#='/path/to/alternate/file'

For more help see:

:h registers
:h quote#
:h :let-@