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Expert software must be able to find various devices in the system. The example shown in Listing 10-15 contains two procedures. The first loops through name entries, invoking a callback function for each one. The second loops through the properties for a name entry, invoking a callback function for each property. It is up to the caller to determine what the callback functions will do, but they could (for example) display a graph of names and properties in a window or identify all name entries that match a complex set of search criteria.
Listing 10-15 Listing names and properties
#include <NameRegistry.h>
OSStatus JoePro_ListDevices(
void (*callback) (
RegCStrPathName *name,
RegEntryID *entry
)
)
{
OSErr err = noErr;
RegEntryIter cookie;
Boolean done;
/*
* Entry iterators are created pointing to the root
* with a RegEntryIterationOp of kRegIterDescendants.
* So, we just need to continue.
*/
RegEntryIterationOp op = kRegIterContinue;
err = RegistryEntryIterateCreate(&cookie);
if (err == noErr) do {
RegEntryID entry;
err = RegistryEntryIterate(&cookie, op, &entry, &done);
if (!done) {
RegCStrPathName *name;
RegPathNameSize len;
err = RegistryCStrEntryToPathSize(&entry, &len);
if (err == noErr) {
name = (RegCStrPathName*) malloc(len);
assert(name != NULL);
err = RegistryCStrEntryToPath(&entry, name, len);
if (err == noErr) {
(*callback)(name, &entry);
}
free(name);
}
RegistryEntryIDDispose(&entry);
}
} while (!done);
RegistryEntryIterateDispose(&cookie);
return err;
}
OSStatus JoePro_ListProperties(
const RegCStrPathName *name,
const RegEntryID *entry,
void (*callback)(
RegPropertyName*,
RegPropertyValue,
RegPropertyValueSize
)
)
{
OSErr err = noErr;
RegPropertyIter cookie;
Boolean done;
err = RegistryPropertyIterateCreate(entry, &cookie);
if (err == noErr) do {
RegPropertyNameBuf property;
err = RegistryPropertyIterate(&cookie, property, &done);
if (!done) {
RegPropertyValue val;
RegPropertyValueSize siz;
err = JoePro_GetProperty(entry, property, &val, &siz);
if (err == noErr) {
(*callback)(property, val, siz);
}
}
} while (!done);
RegistryPropertyIterateDispose(&cookie);
return err;
}