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Inside Macintosh: QuickDraw GX Environment and Utilities /

Chapter 5 - Collection Manager / Collection Manager Reference

Application-Defined Functions /

MyExceptionProc

You provide the MyExceptionProc function (an exception procedure) to handle errors that occur when operating on a collection object.

OSErr MyExceptionProc(Collection target, OSErr whichErr);

target

A reference to the collection object for which the error occurred.

whichErr

The result code associated with the error that occurred.

DESCRIPTION

You create this function to install in a collection object using the SetCollectionExceptionProc function. Subsequently, whenever the Collection Manager is operating on that collection object and an error occurs, the Collection Manager calls this function, sending it a reference to the collection for which the error occurred and the result code associated with the error. You can use this information to handle the error appropriately for your application.

You can use an exception procedure to respond to an error in a number of ways:

• You can change the error from one result code to another by returning as the function result the new result code.
• You can handle the error and return the noErr error code, which indicates that the Collection Manager should return control to the place in your application that generated the error, as if no error had occurred.
• You can use the ANSI C functions setjmp and longjmp to jump out of the exception procedure into code to handle the error.

SEE ALSO

For an example of an exception procedure see "Installing an Exception Procedure" beginning on page 5-45.

To install an exception procedure in a collection object, use the SetCollectionExceptionProc function, which is described on page 5-59.

To obtain a pointer to an existing exception procedure in a collection object, use the GetCollectionExceptionProc function, which is described on page 5-58.