Inside Macintosh: Programmer's Guide to MacApp / Part 1 - MacApp Theory and Architecture

Chapter 6 - Scripting

Components of MacApp's Scripting Support

MacApp provides a number of components that work together to implement scripting support for your application. The sections that follow provide additional detail on these components.

• 'aedt' resource. MacApp also provides an Apple event dispatch table resource that maps a received Apple event (by class ID and descriptor type) to a MacApp command number. You can add 'aedt' resources to establish mappings for custom events.
• 'aete' resource. MacApp provides an Apple event terminology extension resource that defines terminology for the four required Aßpple events, as well as for all of the events in the Core suite supported by MacApp. Your application can modify and extend this resource.
• MScriptableObject. The MScriptableObject class is a mixin (or multiple-inheritance) class that helps an object
  • respond to Apple events
  • get and set object properties
  • describe itself in terms the OSL can understand
  • return the objects it contains
  • have an attached script that can respond to Apple events

    The TDocument, TFile, TWindow, and other MacApp classes mix in this class, and you can add it to any class you define that doesn't already use it.

• MDefaultScriptableObject. MDefaultScriptableObject, a mixin subclass of MScriptableObject, helps an object serve as the destination for Apple events that don't specify a target object. MacApp's TApplication class uses this mixin class and serves as the default target for Apple events.
• TAppleEvent. The TAppleEvent class reads and writes Apple event data and sends Apple events.
• TSetPropertyEvent. The TSetPropertyEvent class, a subclass of TAppleEvent, sends an Apple event to change an object property for objects in a list of one or more objects.
• TCommand. The TCommand class provides a method to create an Apple event to make the command action recordable.
• TSetPropertyCommand. The TSetPropertyCommand class implements an undoable command that can automatically set object properties for your classes that override the GetObjectProperty and SetObjectProperty methods. (You may also have to override the GetSetPropertyInfo method.)
• TClientCommand, TServerCommand. The TClientCommand class and the TServerCommand class provide services for sending an Apple event to an external process, either synchronously or asynchronously, and processing a reply (if one is requested).
• TExecuteScriptCommand. The TExecuteScriptCommand class executes a script.
• TFileBasedDocument. The TFileBasedDocument class contains support for saving an attached script in the resource fork of a document and reading the script when the document is opened.
• TOSADispatcher. The TOSADispatcher class manages the resolution and dispatching of incoming and outgoing object model Apple events. During scripting initialization, the global static field TOSADispatcher::fgDispatcher is set to an instance of TOSADispatcher. The fgDispatcher object dispatches Apple events to specified objects, working with callbacks from the OSL to determine the target object.
• TOSAScriptRep. The TOSAScriptRep class serves as a wrapper for an attached script. The fScript field (of type COSAScript) refers to the actual script object. The TOSAScriptRep class keeps track of references to the script, reads and writes the script, and handles events for the script. You don't reference an instance of this class directly--you work instead through a COSAScriptCntPtr object.
• COSAScript. The COSAScript class is a wrapper for a low-level OSA script. It provides methods that call on OSA routines to send an event to the script, execute the script, set the script, dispose of the script, and so on. The fScriptID field (of type OSAID) specifies the script the class operates on.
• COSAScriptCntPtr. The COSAScriptCntPtr class is used as an accessor for a TOSAScriptRep object. This class allows multiple objects to refer to the same script. A COSAScriptCntPtr object keeps a count of references to the script object and deletes the object if the count goes to 0. The MScriptableObject class has a field of this type to refer to an attached script.

In addition to these components, MacApp processes many Apple events automatically in the TApplication, TDocument, and TWindow classes, although your subclasses may need to provide some additional code.