Advanced Usage of Ranges with Vim Keymappings

Question

I have a mapping in my vimrc that downwardly comments out regions of c code:

nmap comc :normal! I//

Since the \'normal\' ex command

Answer 1

The behavior you requested is normally done with :h map-operator mapping. With this commenting 3 lines down will turn into comc2j though, but 3 lines up is now just as easy: comc2k.

You can also use visual mode without changing your mapping at all: V2kcomc. You will have to add xnoremap with the identical lhs and rhs because nnoremap works only for normal mode. (And do not use nmap.)

Third option is mapping - to something that moves {count} lines up and puts count back:

nnoremap  - (v:count ? ":\\n" . (v:count-1) . 'k' . v:count : '')

. This assumes you are writing 6-comc, not -6comc.

// By the way, I would suggest The NERD Commenter if it comes to the plugin.