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Inside Macintosh: Interapplication Communication /

Chapter 3 - Introduction to Apple Events / Creating and Sending Apple Events

Adding Apple Event Attributes and Parameters

The Apple event record created with the AECreateAppleEvent function serves as a foundation for the Apple event you want to send. Descriptor records and descriptor lists are the building blocks from which the complete Apple event record is constructed. To create descriptor records and descriptor lists and add items to a descriptor list, use the following functions:

Function	Description
AECreateDesc	Takes a descriptor type and a pointer to data and converts them into a descriptor record
AECreateList	Creates an empty descriptor list or AE record.
AEPutPtr	Takes a descriptor type and a pointer to data and adds the data to a descriptor list as a descriptor record; used, for example, to add to a descriptor list a number used as the parameter of an Apple event requesting a calculation.
AEPutDesc	Adds a descriptor record to a descriptor list; used, for example, to add to a descriptor list an alias record used as the direct parameter of an Apple event requesting file manipulation.

To add the remaining attributes and parameters necessary for your Apple event to the Apple event record, you can use these additional Apple Event Manager functions:

Function	Description
AEPutParamPtr	Takes a keyword, descriptor type, and pointer to data and adds the data to an Apple event record as a parameter with the specified keyword (replacing any existing parameter with the same keyword); used, for example, to put numbers into the parameters of an Apple event that asks the server to perform a calculation.
AEPutParamDesc	Takes a keyword and a descriptor record and adds the descriptor record to an Apple event record as a parameter with the specified keyword (replacing any existing parameter with the same keyword); used, for example, to place a descriptor list containing alias records into the direct parameter of an Apple event that requests a server to manipulate files.
AEPutAttributePtr	Takes a keyword, descriptor type, and pointer to data and adds the descriptor record to an Apple event record as an attribute with the specified keyword (replacing any existing attribute with the same keyword); used, for example, to change the transaction ID of an Apple event record that is waiting to be sent.
AEPutAttributeDesc	Takes a keyword and a descriptor record and adds the descriptor record to an Apple event record as an attribute with the specified keyword (replacing any existing attribute with the same keyword); used, for example, to replace the descriptor record used for the target address attribute in an Apple event record waiting to be sent.

Apple event parameters for core events and functional-area events can include descriptions of Apple event objects in special descriptor records called object specifier records. For an overview of object specifier records, see "Working With Object Specifier Records," which begins on page 3-27.