command pattern error fix

behavioral/command/command.go

@@ -0,0 +1,64 @@
+package command
+
+import (
+	"fmt"
+)
+
+type Order interface {
+	execute()
+}
+
+type Stock struct {
+	name string
+	count int
+}
+func (s *Stock) Buy()  {
+	fmt.Println("Bought new item.")
+	s.count += 1
+}
+func (s *Stock) Sell()  {
+	fmt.Println("Sold one item.")
+	s.count -= 1
+}
+
+type BuyStock struct {
+	stock Stock
+}
+func (b *BuyStock) execute()  {
+	b.stock.Buy()
+}
+
+type SellStock struct {
+	stock Stock
+}
+func (b *SellStock) execute()  {
+	b.stock.Sell()
+}
+
+type Broker struct {
+	orders []Order
+}
+func (b *Broker) TakeOrder(o Order)  {
+	b.orders = append(b.orders, o)
+}
+func (b *Broker) PlaceOrders()  {
+	for _,v := range b.orders {
+		v.execute()
+	}
+
+	b.orders = make([]Order, 0)
+}
+
+func Demo() {
+	stock := Stock{name:"phone", count:2}
+	buyStck := &BuyStock{stock}
+	sellStck := &SellStock{stock}
+	broker := &Broker{}
+	broker.orders = make([]Order, 0)
+
+	broker.TakeOrder(buyStck)
+	broker.TakeOrder(sellStck)
+
+	broker.PlaceOrders()
+	
+}