AppleScript: The Definitive Guide, 2nd Edition

Top-Level Entities

A script object's top-level entities are variables defined at the top level of the script object having the special feature that even though they belong to the script object, and even though the rules of scope protect them from being visible to code outside the script object, they can be accessed (retrieved and assigned to) by code outside the script object. A top-level entity is either a script property, a handler, or a script object.

Accessing Top-Level Entities

The most important fact about a script object's top-level entities is that even though they are not directly visible to code outside the script object, they are accessible on demand to any code that can see the script object. This means that they can be both retrieved and assigned to (fetched and set) by such code.

A special way of talking is required for doing this. Because a script object's top-level entities are not visible outside the script object, it is necessary, in effect, to ask the script object politely to yield access to a top-level entity (and the script object always politely complies). We say that to access a script object's top-level entities, you must target that script object. The syntax for doing this comes in two forms:

• Use the of operator (or the 's operator) to specify the top-level entity in relation to its script object. For example:

  script myScript property x : "Howdy" on sayHowdy( ) display dialog x end sayHowdy script innerScript display dialog x end script end script set ...