Display "Loading..." while stuff is done in the background

[donutheist]

I have a script called system-updates.py that checks for system updates on a number of platforms.

usage: system-updates.py [-h] -t TYPE

Check available system updates from different sources

options:
  -h, --help       show this help message and exit
  -t, --type TYPE  The type of update to query; valid choices are: apt, brew, dnf, flatpak, mintupdate, pacman, snap, yay, yay-aur, yum

brew takes a while to load so when I first load the script, there's no output while brew is doing its thing. My goal is for there to be a placeholder that says "Loading..." while brew works in the background and when brew has finished, we have the actual desired output.

I have read that I want to use custom/ipc with hooks but also read hooks are deprecated. Can someone point me to a working example?

SOLUTION

[module/speedtest]
type = custom/ipc
label = %output%
initial = 2
hook-0 = echo "%{F#F0C674}%{F-} Speedtest running..."
hook-1 = ~/.config/polybar/scripts/polybar-speedtest.py --upload --download & polybar-msg -p %pid% action speedtest hook 0

Explanation

1. Setting initial = 2 tells the module to execute hook-1 as the first hook.
2. hook-1 executes the script and puts it in the background.
3. Immediately after executing the script in the background, we use polybar-msg to execute hook-0, which sets the content to the loading text.
4. Since label is %output%, the script output will replace loading text once the test completes.