Legacy Document

Inside Macintosh: QuickDraw GX Environment and Utilities /

Chapter 5 - Collection Manager / Collection Manager Reference

Data Types

Optional Return Value Constants

Many of the Collection Manager functions return multiple pieces of information. For most of these functions, you can specify that you don't want a specific piece of information to be returned by specifying nil for the corresponding parameter when calling the function.

The Collection Manager provides the optional return value constants to make your code easier to read when specifying that you are not interested in obtaining certain types of information:

enum {
   dontWantTag = 0L,
   dontWantId = 0L,
   dontWantSize = 0L,
   dontWantAttributes = 0L,
   dontWantIndex = 0L,
   dontWantData = 0L
};

You can use these enumeration constants in place of the more generic constant nil when specifying that you don't want to receive certain optional return values from a function.