vim + tmux command for getting a tight feedback loop

vim send to tmux pane

TLDR; It saves the file in the current tmux pane, then runs `!!` the previous command in another tmux pane.

This enables a workflow like:
1. Edit code in pane #0
2. Run some test command in pane #1
3. Do more editing in pane #0
4. Hit `,p` to re-run the command from 2. with the new edits
5. Repeat step 2. if you want to run a new test command.

# The command
:map ,p :w \|:! tmux send-keys -t 0:$(tmux display-message -p '\#I').1 C-l "\!\!" Enter Enter <cr><cr>

# Explanation
:map ,p = maps ,p to run this
:w = save the file currently in focus
\| = run another command
:! = run the following in a subshell
tmux send-keys -t = tmux command to send keys to a window addressed by -t <session#>:<window#>.<pane#>
0:$(tmux display-message -p '\#I').1 = the address for tmux to send the keys to. I'll break this down more:
    0 = tmux session number (note: this is hardcoded here, could be made better and more dynamic)
    $(tmux display-message -p '\#I') = gets the current tmux window
    1 = pane number. I usually edit in pane 0 and run tests in pane 1. So this being hardcoded works fine for me.
C-l = Like ^L or Ctrl-L, clears the screen. Runs in the test pane
"\!\!" = puts `!!` in the test pane
Enter Enter = Presses enter twice in the test pane (twice is needed because in zsh !! Enter only inserts the previous command, so a second Enter is needed to run it)
<cr><cr> = <run vim command><back to focus on vim>

Other useful examples:

:map ,c :w \|:! tmux send-keys -t 0:$(tmux display-message -p '\#I').1 C-l C-c Enter Enter <cr><cr>
Use `,c` that just sends ^C. So I can have the same workflow as above, but with long commands.

:map ,t :w \|:! tmux send-keys -t 0:0.2 "clear && python manage.py test" Enter <cr><cr>
Simpler example, map `,t` to run `python manage.py test` in session 0, window 0, pane 2