Obtaining Object Descriptions

Several Navigation Services functions return AEDesc structures describing objects from the network or the file system. You must not assume that an AEDesc structure is of any particular type. If your application needs the structure to be a particular type, you should attempt to coerce the structure using the Apple Event Manager function AECoerceDesc . For more information on coercing Apple event descriptors, see Inside Macintosh: Interapplication Communication .

When Navigation Services passes you an AEDesc structure of type 'typeCString' , the structure describes a network object by using a Uniform Resource Locator (URL). Network objects can be AppleTalk zones or AppleShare servers. For example, an AppleTalk zone called "Building 1 - 3rd floor" would be represented by a URL of 'at://Building 1 - 3rd floor' . An AppleShare server called "Mac Software" in the same zone would be represented by a URL of 'afp:/at/Mac Software:Building 1 - 3rd floor' .

If Navigation Services passes you an AEDesc structure of descriptor type 'typeFSS' describing a directory, the directory's file specification contains an empty name field and its parID field contains the directory ID. If an AEDesc structure of type 'typeFSS' describes a file, its file specification's name field contains the filename and its parID field contains the directory ID of the file's parent directory. This means you can use the name field to determine whether an object is a file or a folder.

If you need to determine the ID of a directory's parent directory, use the File Manager function PBGetCatInfo , described in Inside Macintosh: Files.

Previous | Back Up One Level | Next |