Sets the current resource file.

void UseResFile (
    SInt16 refNum
);

refNum

The file reference number for the resource fork which you wish to set as the current resource fork.

The function searches the list of files whose resource forks have been opened for the file specified here. If the specified file is found, the Resource Manager sets the current resource file to the specified file. If there’s no resource fork open for a file with that reference number, the function does nothing. To set the current resource file to the System file, use 0 here.

DISCUSSION

Open resource forks are arranged as a linked list with the most recently opened resource fork at the beginning. When searching open resource forks, the Resource Manager starts with the most recently opened file. You can call this function to set the current resource file to a file opened earlier, and thereby start subsequent searches with the specified file. In this way, you can cause any files higher in the resource chain to be left out of subsequent searches.

When a new resource fork is opened, this action overrides previous calls to this function and the entire list is searched. For example, if five resource forks are opened in the order R0, R1, R2, R3, and R4, the search order is R4-R3-R2-R1-R0. Calling UseResFile(R2) changes the search order to R2-R1-R0; R4 and R3 are not searched. When the resource fork of a new file (R5) is opened, the search order becomes R5-R4-R3-R2-R1-R0.

You typically call the CurResFile function to get and save the current resource file, UseResFile to set the current resource file to the desired file, then (after you are finished using the resource) UseResFile to restore the current resource file to its previous value. Calling UseResFile(0) causes the Resource Manager to search only the System file’s resource map. This is useful if you no longer wish to override a system resource with one by the same name in your application’s resource fork.

Most of the Resource Manager functions assume that the current resource file is the file on whose resource fork they should operate or, in the case of a search, the file where they should begin. In general, the current resource file is the last one whose resource fork your application opened unless you specify otherwise.

The FSpOpenResFile, HOpenResFile, and OpenResFile functions, which also set the current resource file, override previous calls to UseResFile.

To check for errors, call the ResError function.

AVAILABILITY

Supported in Carbon. Available in Mac OS 8.1 and later when Carbon 1.0.2 or later is present.

© 2000 Apple Computer, Inc. — (Last Updated 5/8/2000)