Volume Number: 20 (2004)
Issue Number: 1
Column Tag: Programming
by Dave Mark
A few weeks ago, I read an article talking about the changes to AppleScript introduced with the release of Panther. I've always been a big AppleScript fan, but this article really piqued my interest. I've been promising myself to spend some quality time digging into dictionaries, scripting environments, and especially using Interface Builder and AppleScript Studio to add Cocoa elements to AppleScript, and now that I've had enough quality play-time, I wanted to start writing about all this cool stuff.
Before we start playing with AppleScript itself, it is worthwhile taking a minute to install Script Menu, the little script icon that appears on the right side of the menu bar and gives you access to a wide range of AppleScripts.
Navigate over to Applications/AppleScript/ and double-click on the script Install Script Menu. The Script Menu icon should appear in your menu bar. My Script Menu is shown in Figure 1. The Script Menu lists scripts from three different places on your hard drive. Local Scripts (also called Library Scripts) are found in the directory /Library/Scripts. User Scripts are found in your home directory, inside /Users/<user name>/Library/Scripts/. And, finally, Application Scripts are found within your User Scripts folder, in a subfolder called /Applications/<appname>/, where <appname> is a folder with the exact same name as the application the scripts are written for.
Figure 1. The Script Menu's menu.
Let's take a look at this in action. Figure 1 shows the vanilla install of Script Menu. The first item, Open Scripts Folder, opens your User Scripts folder in a Finder window. Remember, User Scripts are the scripts you install in your home area.
The second menu item, Hide Library Scripts, removes the Library Scripts from the Script Menu.
Next comes a separator and the list of all the Library Scripts. In this case, all the scripts are divided into subfolders and so appear in the Script Menu divided into submenus.
The screen shot in Figure 1 shows Script Menu as it appears out of the box. Let's add a User Script to the menu. Go into the directory /Applications/AppleScript/ and launch the application Script Editor. Select New from the File menu, type in this simple script:
tell application "Finder" activate end tell
Now select Save from the File menu and save the script in the directory /Users/xxx/Library/Scripts/, where xxx is your user name. I saved my script under the name Dave's Test Script.
A quick note about terminology: The directory /Users/xxx/ is called your home directory and can be represented in the Unix world by the tilde character (~). For example, if I typed in the command:
ls /Users/davemark/
it would be exactly the same as typing:
ls ~
You can also use ~xxx to refer to another user's home directory. So this is also equivalent way to refer to davemark's home directory:
ls ~davemark
And this is one way to list the contents of my User Scripts folder:
ls ~davemark/Library/Scripts
As soon as you save the script, it should appear in your Script Menu. Make sure you are still in Script Editor, then open the Script Menu, select your script (it should be at the very bottom), and watch what happens. Your script is executed, and it does what it is supposed to do. Namely, it tells the Finder to activate, to come to the front. And that is exactly what should happen.
Note that you could have created a folder in your ~/Library/Scripts/ folder and placed the script inside that folder. In that case, the folder would have appeared in the Script Menu as a submenu and the script would have appeared as an item inside that submenu. Try it!
Now for some ultimate coolness! Go back into Script Editor and close the window of the script you just created. Next, hold down the option key, click on the Script Menu and select your script again. Instead of running the script, Mac OS X opens the script in Script Editor. An excellent feature!
Your next step is to add an application-specific folder to your User Script directory. The idea here is to have a directory for all your scripted applications and have the scripts for that app appear in the Script Menu whenever that application is front most. You'll see what I mean in a minute.
Start off by creating a folder called Applications in your ~/Library/Scripts/ folder. Within that folder, create a folder with the exact name of one of your applications. For example, create a folder named Finder. Note that spelling is critical or this won't work. Now go into Script Editor and create this script:
tell application "Script Editor" activate end tell
Save the script in the ~/Library/Scripts/Applications/Finder folder. I saved my script under the name Dave's Finder Script. Once the script is saved, click on the Script Menu. If you are in the Finder, your Finder scripts will appear at the bottom of the menu. If you are in another app, the Finder scripts will be replaced by the scripts (if any) for that app.
Figure 2 shows my Script Menu, as selected from within the Finder. Note that the User Script I created, Dave's Script, is second from the bottom, and the Finder script is at the very bottom. When I run Dave's Script, the Finder comes to the front. Then, within the Finder, when I run Dave's Finder Script, Script Editor comes to the front. Try this yourself.
Figure 2. The Script Menu with the addition of my test script from my User Scripts folder and my Finder
Script from my Applications/Finder/ folder.
Apple's web site is full of cool sample scripts. This one will create a folder for the front most application in the ~/Library/Scripts/Applications/ folder:
http://www.apple.com/applescript/scriptmenu/downloads/addfrontapp.dmg
Now that you have a home for all your scripts, let's start exploring AppleScript itself. One place to start is with an application's dictionary. Each application's dictionary entry gives specific information about the classes and commands that the application supports.
Launch Script Editor. If it is not already open, open the Library window by selecting Library from the Window menu. Figure 3 shows my Script Editor library.
Figure 3. Script Editor's Library window.
Double-click on the Finder entry in the Library window. The window shown in Figure 4 will appear. There is a lot of information to digest in this window. Spend a few minutes opening the various disclosure triangles (I've opened some of them in Figure 4) and clicking on the various commands and classes in the left scrolling pane.
If you've ever done any pre-OS X Mac development, you've likely encountered the concept of Apple events. Want an app to quit? Send it a quit Apple event. Want an app to open or print a file? Send it an open or print Apple event. AppleScript is basically a sophisticated language you can use to control a scriptable application by sending it events and scripting the results.
Figure 4. The Finder's dictionary, showing the application class in the Finder Basics suite.
The most basic set of commands are organized into something called the Standard Suite. Most applications support the Standard Suite. The Standard Suite commands are close, count, data size, delete, duplicate, exists, make, move, open, print, quit, and select.
Many applications add their own sets of commands to the Standard Suite. For example, the Finder adds in a set of classes and commands called Finder Basics and another called Finder items. The main pain of Figure 4 shows the details of the application class in the Finder Basics suite. Notice that the list is divided into Elements and Properties. Elements are the objects contained in a class, while properties are more like preferences - unique within a class. Elements can be plural while a property is usually singular. A typical Finder element might be the list of items on the desktop. A typical Finder property might be the current selection.
Let's play with this a bit.
Create a new script and type in this code:
tell application "Finder" get home end tell
When you run this script, Script Editor should display results in its Result pane. My results are shown in Figure 5. Notice that home is a Finder property containing the home directory. If you look towards the bottom of Figure 4, you'll see that it is also marked [r/o], meaning the property is read-only.
Figure 5. A simple Finder script, with the results shown in the Result pane.
Now edit the script like so:
tell application "Finder" get items of home end tell
While the first script gave you the value of the home property, this script returns the list of items in the home folder. Here's the result I got when I ran this script:
{folder "Desktop" of folder "davemark" of folder "Users" of startup disk of
application "Finder", folder "Documents" of folder "davemark" of folder "Users" of startup
disk of application "Finder", folder "Library" of folder "davemark" of folder "Users" of
startup disk of application "Finder", folder "Magazines" of folder "davemark" of folder
"Users" of startup disk of application "Finder", folder "Movies" of folder "davemark" of
folder "Users" of startup disk of application "Finder", folder "Music" of folder "davemark"
of folder "Users" of startup disk of application "Finder", folder "Pictures" of folder
"davemark" of folder "Users" of startup disk of application "Finder", folder "Public" of
folder "davemark" of folder "Users" of startup disk of application "Finder", folder "Sites"
of folder "davemark" of folder "Users" of startup disk of application "Finder"}
As you can see, this is a comma-delimited list, wrapped in curly braces. This kind of result is typical in AppleScript. As you can see in the top of Figure 4, an item element can be specified "by numeric index, before/after another element, by name, as a range of elements, satisfying a test." For example, we can refer to item 3, as in this script:
tell application "Finder" get item 3 of home end tell
As you might expect, here's the result of this script:
folder "Library" of folder "davemark" of folder "Users" of startup disk of application "Finder"
There is a ton of cool stuff to play with here. In the Finder dictionary, look in the Finder items suite, at the item class to learn everything you could possibly want to know about items. For example, you'll see a bounds property, which describes the bounding rectangle of the specified item. You might extend the script above to:
tell application "Finder" get bounds of item 3 of home end tell
You get the idea. The dictionary is an incredibly powerful tool for unlocking the mysteries of AppleScript. Play more. I'll be back next month with more fun stuff! J
Dave Mark is a long-time Mac developer and author and has written a number of books on Macintosh development, including Learn C on the Macintosh, Learn C++ on the Macintosh, and The Macintosh Programming Primer series. Be sure to check out Dave's web site at http://www.spiderworks.com.
