Vim Nonrecursive Mappings

December 17, 2016

My first PR to a new Vim plugin was merged this week, check it out, adding non-recursive Vim mappings to vim-termbux.

vim-termbux is a plugin by my friend Dillon Hafer that emulates the behavior of vim-turbux— sending test run output to somewhere outside of Vim– in iTerm. If you write a lot of tests in iTerm and Vim, but prefer to stay outside of Tmux for whatever reason (fingers don’t like the mappings, etc.), than this plugin is for you.

My patch changes this:

nmap <leader>t :call <SID>ITermTestRunnerLine()<cr>
nmap <leader>T :call <SID>ITermTestRunnerFile()<cr>

To this:

nnoremap <leader>t :call <SID>ITermTestRunnerLine()<cr>
nnoremap <leader>T :call <SID>ITermTestRunnerFile()<cr>

This is the mapping that enables the plugin to work.

I’m reading Learn VimScript The Hard Way, and this was one of my first practical applications of that. As the pull request summary explains:

All Vim mappings should be non-recursive. Although unlikely, if your second argument is ever mapped to something else in a different place, nnoremap will prevent a recursive call and just execute the second argument as written.

Source

To summarize, non-recursive mappings are less likely to surprise you, and should be the default. I haven’t seen this go wrong myself, and am trusting the expert. It’s nice to learn some things from the experience of somebody else.