In the following code, I create one peg puzzle then do a move on it which adds a move to its movesAlreadyDone vector. Then I create another peg puzzle then do a move on it which adds a move to its movesAlreadyDone vector. When I print out the values in that vector for the second one, it has the move in it from the first one along with the move from the second one. Can anyone tell me why it seems to be assigning by reference and not value? Are vector assignments copied by value or by reference in Google's Go language?

package main

import "fmt"
import "container/vector"

type Move struct { x0, y0, x1, y1 int }

type PegPuzzle struct {
    movesAlreadyDone * vector.Vector;
}

func (p *PegPuzzle) InitPegPuzzle(){
    p.movesAlreadyDone = vector.New(0);
}

func NewChildPegPuzzle(parent *PegPuzzle) *PegPuzzle{
    retVal := new(PegPuzzle);
    retVal.movesAlreadyDone = parent.movesAlreadyDone;
    return retVal
}

func (p *PegPuzzle) doMove(move Move){
    p.movesAlreadyDone.Push(move);
}

func (p *PegPuzzle) printPuzzleInfo(){
    fmt.Printf("-----------START----------------------\n");
    fmt.Printf("moves already done: %v\n", p.movesAlreadyDone);
    fmt.Printf("------------END-----------------------\n");
}

func main() {
    p := new(PegPuzzle);
    cp1 := new(PegPuzzle);
    cp2 := new(PegPuzzle);

    p.InitPegPuzzle();

    cp1 = NewChildPegPuzzle(p);
    cp1.doMove(Move{1,1,2,3});
    cp1.printPuzzleInfo();

    cp2 = NewChildPegPuzzle(p);
    cp2.doMove(Move{3,2,5,1});
    cp2.printPuzzleInfo();
}

Any help will be greatly appreciated. Thanks!