A better way to activate menu items from AppleScript

Sep 28, '06 07:30:07AM

Contributed by: jacobolus

There have been several specific hints on this site which use UI scripting to perform tasks that applications' AppleScript dictionaries don't otherwise allow. Unfortunately, UI scripting is a complicated pain to get right. In particular, the code Apple uses as a demonstration on apple.com is very long, and not particularly intuitive:

tell application "Finder"
end tell

tell application "System Events"
    tell process "Finder"
        tell menu bar 1
            tell menu bar item "View"
                tell menu "View"
                    tell menu item "Arrange By"
                        tell menu "Arrange By"
                            click menu item "Size"
                        end tell
                    end tell
                end tell
            end tell
        end tell
    end tell
end tell
To that end, I created a helper function, which I call menu_click, which can be added to any script to allow the above code to instead be written as:
tell application "Finder" to activate
menu_click({"Finder", "View", "Arrange By", "Size"})
I find these two lines much clearer and easier to understand than the 19 lines of code that Apple uses for the same purpose.

To be fair, even without my function, this code could be written:

tell application "Finder" to activate
tell application "System Events"
    click menu item "Size" of ((process Finder)'s (menu bar 1)'s 
        (menu bar item "View")'s (menu "View")'s 
        (menu item "Arrange By")'s (menu "Arrange By"))
end tell
I still like my version better ;).

To be even fairer, Apple tries to help out with their own helper functions. These are useful, but they are overly complicated to use, because a separate function is needed for each level of menu hierarchy the script author wants to use. For instance, the do_menu handler can execute the File -> New command, but not the Edit -> Insert -> Line Break command, which requires the more complicated do_submenu handler. For more deeply nested menu options, we'd eventually need a do_subsubsubmenu handler, if we continued in Apple's footsteps.

Thus, the menu_click handler was born. Just add the following code to your script, and then call menu_click with a list containing the application name, followed by the menu command. Just so we're clear, I'll repeat myself. Copy and paste the "code" section that immediately follows this sentence into your script verbatim (it can be anywhere: top or bottom makes no difference). Then anywhere in the rest of your script, you can call the helper function.

-- `menu_click`, by Jacob Rus, September 2006
-- Accepts a list of form: `{"Finder", "View", "Arrange By", "Date"}`
-- Execute the specified menu item.  In this case, assuming the Finder 
-- is the active application, arranging the frontmost folder by date.

on menu_click(mList)
    local appName, topMenu, r

    -- Validate our input
    if mList's length < 3 then error "Menu list is not long enough"

    -- Set these variables for clarity and brevity later on
    set {appName, topMenu} to (items 1 through 2 of mList)
    set r to (items 3 through (mList's length) of mList)

    -- This overly-long line calls the menu_recurse function with
    -- two arguments: r, and a reference to the top-level menu
    tell app "System Events" to my menu_click_recurse(r, ((process appName)'s 
        (menu bar 1)'s (menu bar item topMenu)'s (menu topMenu)))
end menu_click

on menu_click_recurse(mList, parentObject)
    local f, r

    -- `f` = first item, `r` = rest of items
    set f to item 1 of mList
    if mList's length > 1 then set r to (items 2 through (mList's length) of mList)

    -- either actually click the menu item, or recurse again
    tell app "System Events"
        if mList's length is 1 then
            click parentObject's menu item f
            my menu_click_recurse(r, (parentObject's (menu item f)'s (menu f)))
        end if
    end tell
end menu_click_recurse

Here is a (very simple) example demonstrating the use of these functions. To get the example to work, make sure you copy both the helper functions above and the example code following into the same script.
-- This example script turns on the "iTunes Visualizer" visualizer, full screen
tell app "iTunes" to activate
menu_click({"iTunes", "View", "Visualizer", "iTunes Visualizer"})
menu_click({"iTunes", "View", "Turn On Visualizer"})
menu_click({"iTunes", "View", "Full Screen"})
Happy menu-item selecting. Remember to turn on UI scripting before you run these scripts, or they won't work.

[robg adds: I haven't tested this one.]

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