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Inside Macintosh: Interapplication Communication /

Chapter 6 - Resolving and Creating Object Specifier Records / Reference to Resolving and Creating Object Specifier Records

Application-Defined Routines / Object Accessor Functions

MyObjectAccessor

Object accessor functions locate Apple event objects of a specified object class in a container identified by a token of a specified descriptor type.

FUNCTION MyObjectAccessor (desiredClass: DescType; 
                           containerToken: AEDesc; 
                           containerClass: DescType; 
                           keyForm: DescType; keyData: AEDesc; 
                           VAR theToken: AEDesc; 
                           theRefcon: LongInt): OSErr;

desiredClass

The object class of the desired Apple event objects.

containerToken

A token that specifies the container of the desired Apple event objects.

containerClass

The object class of the container.

keyForm

The key form specified by the object specifier record being resolved.

keyData

The key data specified by the object specifier record being resolved.

theToken

The token returned by the MyObjectAccessor function.

theRefcon

A reference constant that the Apple Event Manager passes to the object accessor function each time it is called.

DESCRIPTION

Each object accessor function provided by your application should either find elements of a specified object class or find properties of an Apple event object. The AEResolve function uses the object class ID of the specified Apple event object and the descriptor type of the token that identifies the object's container to determine which object accessor function to call. To install an object accessor function either in your application's object accessor dispatch table or in the system object accessor dispatch table, use the AEInstallObjectAccessor function, which is described on page 6-91.

SPECIAL CONSIDERATIONS

If the Apple Event Manager receives the result code errAEEventNotHandled after calling an object accessor function, it attempts to use other methods of locating the requested objects, such as calling an equivalent system object accessor function. Thus, an object accessor function that can't locate a requested object should return errAEEventNotHandled. This allows the Apple Event Manager to try other object accessor functions that may be available.

RESULT CODES

noErr	0	No error occurred
errAEEventNotHandled	-1708	The object accessor function is unable to locate the requested Apple event object or objects

SEE ALSO

For information about installing object accessor functions, see "Installing Entries in the Object Accessor Dispatch Tables," which begins on page 6-27.

For information about writing object accessor functions, see "Writing Object Accessor Functions," which begins on page 6-34.