Method preferMethod

src/jvm/clojure/lang/MultiFn.java:84–103

(Object dispatchValX, Object dispatchValY)

}

public MultiFn preferMethod(Object dispatchValX, Object dispatchValY) {
	rw.writeLock().lock();
	try
		{
		if(prefers(hierarchy.deref(), dispatchValY, dispatchValX))
			throw new IllegalStateException(
					String.format("Preference conflict in multimethod '%s': %s is already preferred to %s",
					              name, dispatchValY, dispatchValX));
		preferTable = getPreferTable().assoc(dispatchValX, RT.conj((IPersistentCollection) RT.get(getPreferTable(),
		                                                                                     dispatchValX,
		                                                                                     PersistentHashSet.EMPTY),
		                                                      dispatchValY));
		resetCache();
		return this;
		}
	finally
		{
		rw.writeLock().unlock();
		}
}

private boolean prefers(Object hierarchy, Object x, Object y) {
	IPersistentSet xprefs = (IPersistentSet) getPreferTable().valAt(x);