OS X Mountain Lion Bible

Analyzing a Script

Looking through the script that you wrote in the previous example, you may be surprised to learn that AppleScript doesn't know anything about the Finder's operations. Although your recorded script contains commands that set the position, size, and view of a Finder window and selects an item in it, AppleScript doesn't know anything about these or other Finder operations. In fact, AppleScript knows how to perform only the five following commands:

• copy

• count

• get

• run

• set

AppleScript learns about moving and resizing Finder windows from the Finder; even the tell command that's ubiquitous in AppleScripts is a command it learns from the Finder. More generally, AppleScript learns about commands in a script from the application that the script controls. The application has a dictionary of AppleScript commands that work with the application. The dictionary defines the syntax of each command. AppleScript learns about more commands from scripting addition files on your computer. Each scripting addition file contains a dictionary of supplemental AppleScript commands.

Learning application commands and objects

Look at the sample script you created. The first statement says:

tell application “Finder”

To AppleScript, this statement means “start working with the application named Finder.” When AppleScript sees a tell application statement, it looks at the dictionary for the specified application and figures out what commands the application understands. For example, by ...