hide comment line vim

hide_cmdline.vimrc

set lines+=1

let s:is_cmdline_open = 0
function! s:cmdline(key)
    if a:key ==# ':'
        if !s:is_cmdline_open
            let &lines-=1
            let s:is_cmdline_open = 1
            redraw
        endif
    else
        if s:is_cmdline_open
            let &lines+=1
            let s:is_cmdline_open = 0
        endif
    endif
    return a:key
endfunction

nnoremap <expr> : <sid>cmdline(':')
cnoremap <expr><silent> <cr> <sid>cmdline("\<cr>")
cnoremap <expr><silent> <esc> <sid>cmdline("\<C-c>")
cnoremap <expr><silent> <C-c> <sid>cmdline("\<C-c>")