Get the current mode in vimscript/Python

Question

I have a vimscript function that needs to call Python code, depending on what mode I'm in. Some posts here recommend to use :mode() such as Within a function, Is there a way to determine if vim is in insert mode? and How to get the current mode in vim?

The problem that I'm having is that mode() doesn't work as expected for me.

For example, if you do this ...

function Test()
echo mode()
endfunction

vnoremap <leader>v :call Test()<CR>

and then go into visual mode or visual block mode or visual line mode (v, <ctrl-v>, V) and run <leader>v, this function prints "n" for all three.

What I wanted to do was to, in python, call

vim.command('let l:mode = mode()')
mode = vim.eval('l:mode')

and then use the mode variable for my script but because it always seems to return "n", this hasn't worked.

Any advice is appreciated

Answer 1

As the doc :h mode() says:

    [mode()] is useful in the 'statusline' option or when used
    with |remote_expr()| In most other places it always returns
    "c" or "n".

Depending on what your code should do, you could use an <expr> mapping like this:

function! Test()
    echo mode()
endfunction

xnoremap <expr> <leader>v Test() " echos 'v'
nnoremap <expr> <leader>v Test() " echo 'n'

I think the problem comes from the fact that when your mapping uses : to switch to command line it exits visual mode and returns a different mode from what you are looking for.

Maybe you would be interested instead in :h visualmode() which allows you to get the last visual mode used in the current buffer.

---

Otherwise I think your best bet is to create two mappings in normal mode and in visual mode and to give them the mode as parameter like this:

function! Test(mode)
    echo a:mode
endfunction

xnoremap <leader>v :call Test('v')<CR>
nnoremap <leader>v :call Test('n')<CR>

This way you don't need to rely on mode() to know in which mode you are.