3.1. Getting Started Just as you can't surf the Web without a Web browser, you can't create AppleScripts without a script-editing program. The aptly named Script Editor (in your Applications  AppleScript folder) is the simplest program for the job, but feel free to try any of the other editors listed on Sidebar 2.6. Before you start diving into the following sections, the first thing you'll need to do is launch Script Editor (Chapter 2). With this blank scripting slate before you, it's possible to accomplish such neat tasks as: Displaying a dialog box using a single line of code (see below) Performing basic arithmetic (see the next page) Getting the contents of your Clipboard (the place where Mac OS X stores information when you choose Edit Cut or Edit Copy [see the next page])
But that's only the beginning. So strap on that beanie with the propeller on top, and get ready to write your first lines of AppleScript. 3.1.1. Displaying a Simple Dialog Box As you saw on Section 1.1.4, dialog boxes are the most common way for AppleScript to interact with you. That's because, on their own, scripts can't display complex interface elements like pop-up menus, checkboxes, or toolbars. As you're starting out in AppleScript, therefore, you'll use the display dialog command even more than you breathe. Here's how: With Script Editor open, type the following command in the Script Field: display dialog "Hello! I'm your first AppleScript."
As you type in the command, you'll notice it appears as a bunch of purple text. That's Script Editor's way of telling you that it hasn't checked your command for AppleScript compliance yet. Click the Compile button. That tells Script Editor, "Make sure I didn't make any typos in my AppleScript commands" (Section 2.1.1.4). Click Run. Under the hood, AppleScript sees your display dialog command and realizes that it has to put together a dialog box with your provided text. After a fraction of a second, you see the fruits of AppleScript's labor (Figure 3-1).
 | If you don't see that dialog box, see Table 14-1 for an explanation of what may have gone wrong. |
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 | Figure 3-1. Your first script running. It's not much, but it's a start. |
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No matter which button you click (Cancel or OK), AppleScript dismisses your dialog box. If you start to suffer from dialog box withdrawal, though, simply click Run again to redisplay the dialog box. 3.1.2. Displaying Numbers In general, the display dialog command just presents whatever follows it. In the previous example, you typed a string (a series of characters surrounded by double-quotes), so display dialog showed that. On the other hand, you can just as easily use a number with the display dialog command, since AppleScript automatically converts (or coerces) the number to its textual representation. For example, if you opened a new script window (File New) and ran this command: display dialog 4.52
you'd see a dialog box with 4.52 in it. The fun doesn't stop there, though. If you'd like, you can put math expressions after the display dialog command, like this: display dialog (1 + 3 - 9)
When you run that command, AppleScript figures out the value of the expression (in this case, 1+3-9), and displays the result in a dialog box: -5. | AppleScript supports the full range of operations you'd perform on a pocket calculator: addition (symbolized by a + sign), subtraction (indicated by a - sign), multiplication (shown with an *), and division (shown with a / ). Just like your middle school math teacher taught you, AppleScript follows the proper order of mathematical operations: parentheses first, then multiplication and division, and finally addition and subtraction. That means that 4+2*3 would come out to 10, whereas (4+2)*3 would come out to 18. To avoid confusion, experienced scripters use parentheses even when they're not strictly necessary. That single change can save you hours of time trying to track down math errors. |
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3.1.3. More than One Command So far, you've been writing scripts with a single command in themknown by geeks as "one-liners." If you were restricted to one command per script, though, you'd have quite a time trying to write that workflow-integration script you've been dreaming about. Luckily, AppleScript lets you put as many commands as you want in your script. When you click Run, AppleScript runs the first command, waits for it to finish, runs the second command, waits for it to finish, and so on. Here's a simple example: display dialog "This script shows the text on your clipboard. Click OK to proceed." display dialog (the clipboard) -- This command runs after you click OK display dialog "Thank you for running Clipboard Viewer."
This script shows three dialog boxes, one at a time. The first dialog box explains what the script does. If you're creating a new script, it's often a good idea to have an explanatory dialog box at the beginning. The second dialog box displays the contents of the Clipboard. Any text you've copied (using, for example, the Edit Copy command) is shown onscreen. | In AppleScript, all you need to do to get the contents of the Clipboard is write the clipboard. |
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The text after the two hyphens is a commentsomething that AppleScript ignores. See the Sidebar 3.1 sidebar (Sidebar 3.1) for more about this feature. Finally, the third dialog box displays a goodbye note. This, of course, is completely optional in your own scripts.
| If, at any point, you click the Cancel button in a dialog box, the script stops running. In fact, that's just about the only way to make a script stop running while a dialog box is open; if you attempt to click the Stop toolbar button, Script Editor just beeps. |
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Up to Speed
Making Comments | When you're reading through a script, many of the commands are probably pretty self-evident. Unfortunately, there can also be some that seem totally foreign. In those cases, you can use a commenta section of text in plain Englishto remind yourself how the commands work. AppleScript supports two kinds of comments: single-line and multi-line. No matter which kind of comments you use, AppleScript ignores what's insidethey're there solely for your benefit. You'd write a single-line comment like this: display dialog "Watermelon" --a dialog box
AppleScript understands that everything from the double-hyphen to the end of the line is a comment. To AppleScript, therefore, the previous command is identical to this one: display dialog "Watermelon"
You'll often see a single-line comment used to clarify how a particular command works. On the other hand, a multi-line comment is useful for explaining how a big chunk of your script works. It could look something like this: (* Please note that this script may irrevocably erase your ENTIRE hard drive. Use with caution, or on someone else's computer. *)
Everything between the parentheses and asterisks is understood to be a commentno matter how many lines it spans. You'll often see multi-line comments in the scripts that come with your Mac, since they contain Apple's copyright information. |
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-C) to copy that text to your Clipboard. When you run the script, the words you copied will show up in the second dialog box.