package singleton;
 
import java.util.HashMap;
import java.util.Map;
 
public class RegSingleton {
	private static RegSingleton _instance;
	private static Map _registry = new HashMap();
 
	protected RegSingleton() { }
 
	public static void Register(String name, RegSingleton obj) {
		_registry.put(name, obj);
	}
 
	public static RegSingleton Instance() {
		if (_instance == null) {
			// User define this name in system property file
			// before program starts
			String name = System.getProperty("patterns.book.singletonName");
			_instance = RegSingleton.Lookup(name);
		}
		return _instance;
	}
 
	protected static RegSingleton Lookup(String name) {
		return (RegSingleton) _registry.get(name);
	}
}