Hammerspoon

Test driving Hammerspoon for automation on macOS

Notes

Reading posts from Hillel Wayne on his use of (Windows-only) AutoHotkey finally motivated me to search out an equivalent for macOS.

The option that immediately caught my attention was Hammerspoon.

About Hammerspoon

Coincidentally, Hammerspoon just celebrated its 10th anniversary with a 1.0.0 release.

What does it do?

• uses Lua code to interacts with macOS APIs for applications, windows, mouse pointers, filesystem objects, audio devices, batteries, screens, low-level keyboard/mouse events, clipboards, location services, wifi, and more.
• allows you to implement custom automations by writing Lua code, or use pre-existing “Spoons”

Installation

• Download the latest
• unzip and drag Hammerspoon.app to the Applications folder
• run Hammerspoon.app for initial launch and to configure preferences

Getting Started

Edit ~/.hammerspoon/init.lua (also available via “Open Config” from Hammerspoon menu). A first example from the Getting Started Guide simply displays a notification popup when a hotkey combo is pressed:

hs.hotkey.bind({"cmd", "alt", "ctrl"}, "W", function()
  hs.alert.show("Hello World!")
end)

Attempting a more involved example. This binds the cmd-shift-L key combo to a function that copies the selected text in the Terminal application, converts it to lowercase, and puts it on the clipboard.

-- Convert currently selected text in the Terminal to lowercase and put on the clipboard
-- Hammerspoon will need accessibility permissions in macOS to control other apps.
hs.hotkey.bind({"cmd", "shift"}, "L", function()
  -- Get the currently focused window
  local focusedWindow = hs.window.focusedWindow()
  local app = focusedWindow:application()

  -- Check if the focused application is Terminal
  if app:name() == "Terminal" then
      -- Simulate Cmd+C to copy the selected text to the clipboard
      hs.eventtap.keyStroke({"cmd"}, "C")

      -- Wait a short time to ensure the clipboard is updated
      hs.timer.usleep(10000)  -- 10 milliseconds

      -- Get the clipboard content
      local selectedText = hs.pasteboard.getContents()

      if selectedText then
          -- Convert the selected text to lowercase
          local lowerText = string.lower(selectedText)

          -- Set the clipboard to the lowercase text
          hs.pasteboard.setContents(lowerText)

          -- Show a notification
          hs.alert.show(lowerText .. " is now in the clipboard")
      end
  else
      hs.alert.show("Focus on Terminal to use this shortcut. Current focus:" .. app:name())
  end
end)

Using a “Spoon”

Let’s try a Spoon. I’m going to install Cherry. Cherry tomato (a tiny Pomodoro) – a Pomodoro Timer for the menubar

To install it:

• download the zip file from our Spoon repository: https://github.com/Hammerspoon/Spoons/raw/master/Spoons/Cherry.spoon.zip
• unzip Cherry.spoon.zip
• double click the Cherry.spoon file - Hammerspoon will install it amd remove the Cherry.spoon file

It needs to be enabled in ~/.hammerspoon/init.lua, e.g:

-- Load the Cherry Spoon with default settings and hotkey (cmd-alt-ctrl-c)
hs.loadSpoon("Cherry")
spoon.Cherry:bindHotkeys()

Then a default 25-minute pomodoro timer can be started with the hotkey or selecting “Start” from the cherry menubar item.

Credits and References

• Hammerspoon - a tool for powerful automation of macOS
  • https://github.com/Hammerspoon/hammerspoon - sources
  • Getting Started Guide
  • “Spoons”
• Learn AutoHotKey by stealing my scripts
• AutoHotkey - the ultimate automation scripting language for Windows