/**
 * A Small example of the effect of call by sharing in Java
 * The point is that the passed reference is shared to the 
 * subroutine.  As a result, the subroutine can change the contents
 * of the shared reference.  It can even change the reference inside
 * the subroutine, but it cannot change the reference in the caller.
 * This ends up looking a lot like the reference is passed by value.
 * 
 * Created: Nov 2022 gtowell
 * @author gtowell
 */

public class CallShar {
    /** 
     * A private class just so I have somethig to pass around whose internals I 
     * can change.
     */
    private class CSA {
        int iVal = 5;

        public String toString() {
            return String.format("CSA %d", iVal);
        }
    }

    public void share(CSA item) {
        item.iVal = 20;
        System.out.format("share  1: %s    [%d]\n", item, System.identityHashCode(item));
        item = new CSA();
        item.iVal = 10;
        System.out.format("share  2: %s    [%d]\n", item, System.identityHashCode(item));
    }

    public void doo() {
        CSA iii = new CSA();
        iii.iVal = 50;
        System.out.format("doo 1: %s    [%d]\n", iii, System.identityHashCode(iii));
        share(iii);
        System.out.format("doo 2: %s    [%d]\n", iii, System.identityHashCode(iii));
    }

    public static void main(String[] args) {
        (new CallShar()).doo();
    }
}