AppleScript in a Nutshell

Application Class

Many scriptable applications define an application class, which is the gem to study if you want to automate that program. Your quickest route to the application class is its description in the program’s dictionary. We mentioned before that Mac programs can expose an object model to scripting components like AppleScript. An object model is a software abstraction, usually in tree-like form, showing the Apple event objects and Apple events that you can use with a program.

The application class is the root or top-level class in the program’s object model. An Apple-event object model shows the application class and all of its elements and properties (if it has any defined elements). Figure 1-7 shows a simple object model for Sherlock 2, the Mac’s fancy Find program. Sherlock 2 has three properties and contains zero or more channel elements. (I am sticking to the strict definition of an object’s elements, which is that an object can have zero or more of them. In reality, Sherlock 2 always has at least one defined channel, which is the domain that it is searching.)

channel elements are themselves objects with their own properties: “all search sites” and “name” (e.g., the name of one channel is “Internet”). When in doubt about how to script a program, always use the program’s dictionary to examine its application class. The elements and properties of the application class are the things that you will be able to control and derive values from with your AppleScripts. ...