Toggle the mode in a vim function

Question

I am trying to modify the following function:

function! changeNumber() abort
    if &nu + &rnu == 0
        set nopaste
        " how to set normal mode after the function exits?
    else
        set paste
        " how to set insert mode after the function exits?
    endif
endfunction

Basically, I'm trying to write a copy-paste helper function that removes the line numbers and enters/exits insert mode when it runs (for the full problem, see: https://stackoverflow.com/a/61952187/651174).

Answer 1

You can use :startinsert and :stopinsert here.

From :help :startinsert:

Start Insert mode just after executing this command. Works like typing i in Normal mode. When the ! is included it works like A, append to the line. Otherwise insertion starts at the cursor position. Note that when using this command in a function or script, the insertion only starts after the function or script is finished.

So your function snippet becomes:

function! changeNumber() abort
    if &nu + &rnu == 0
        set nopaste
        stopinsert
    else
        set paste
        startinsert
    endif
endfunction

While you might possibly consider using the startinsert! variant to append at the end of the line instead.