Legacy Document

Inside Macintosh: More Macintosh Toolbox /

Chapter 1 - Resource Manager / Resource Manager Reference

Resource Manager Routines / Getting a Unique Resource ID

UniqueID

You can use the UniqueID function to get a unique resource ID for a resource.

FUNCTION UniqueID (theType: ResType): Integer;

theType

A resource type.

DESCRIPTION

The UniqueID function returns as its function result a resource ID greater than 0 that isn't currently assigned to any resource of the specified type in any open resource fork. You should use this function before adding a new resource to ensure that you don't duplicate a resource ID and override an existing resource.

SPECIAL CONSIDERATIONS

In versions of system software earlier than System 7, the UniqueID function may return a resource ID in the range 0 through 127, which is generally reserved for system resources. You should check that the resource ID returned is not in this range. If it is, call UniqueID again, and continue doing so until you get a resource ID greater than 127.

In System 7 and later versions, UniqueID won't return a resource ID of less than 128.

SEE ALSO

To check for errors, call the ResError function as described on page 1-47.

For more information about restrictions on resource IDs for specific resource types, see "Resource IDs" on page 1-42.