Add an example of how to use multiple menus

fixes #15

README.md

@@ -69,7 +69,7 @@ menu := wmenu.NewMenu("What is your favorite food?")
 menu.Action(func (opts []wmenu.Opt) error {fmt.Printf(opts[0].Text + " is your favorite food."); return nil})
 menu.Option("Pizza", nil, true, nil)
 menu.Option("Ice Cream", nil, false, nil)
-menu.Option("Tacos", nil, false, func() error {
+menu.Option("Tacos", nil, false, func(opt wmenu.Opt) error {
   fmt.Printf("Tacos are great")
 })
 err := menu.Run()

example/main.go

@@ -0,0 +1,76 @@
+//package main is to show how multiple menus can be used with eachother
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/dixonwille/wmenu"
+)
+
+type menuItem int
+
+const (
+	pizza menuItem = iota
+	iceCream
+	tacos
+)
+
+var menuItemStrings = map[menuItem]string{
+	pizza:    "Pizza",
+	iceCream: "Ice Cream",
+	tacos:    "Tacos",
+}
+
+func main() {
+	mm := mainMenu()
+	err := mm.Run()
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+}
+
+func mainMenu() *wmenu.Menu {
+	menu := wmenu.NewMenu("What is your favorite food?")
+	menu.Option(menuItemStrings[pizza], pizza, true, nil)
+	menu.Option(menuItemStrings[iceCream], iceCream, false, nil)
+	menu.Option(menuItemStrings[tacos], tacos, false, func(opt wmenu.Opt) error {
+		fmt.Printf("Tacos are great!\n")
+		return nil
+	})
+	menu.Action(func(opts []wmenu.Opt) error {
+		if len(opts) != 1 {
+			return errors.New("wrong number of options chosen")
+		}
+
+		tm := toppingsMenu(opts[0].Value.(menuItem))
+		return tm.Run()
+	})
+	return menu
+}
+
+func toppingsMenu(favorite menuItem) *wmenu.Menu {
+	menu := wmenu.NewMenu(fmt.Sprintf("What is your favorite topping for %s?", menuItemStrings[favorite]))
+	if favorite == pizza {
+		menu.Option("Meat", nil, true, nil)
+		menu.Option("Cheese", nil, false, nil)
+		menu.Option("Vegitables", nil, false, nil)
+	}
+	if favorite == iceCream {
+		menu.Option("Fruit", nil, true, nil)
+		menu.Option("Chocolate Syrup", nil, false, nil)
+		menu.Option("Caramel Syrup", nil, false, nil)
+	}
+	menu.Action(func(opts []wmenu.Opt) error {
+		if len(opts) != 1 {
+			return errors.New("wrong number of options chosen")
+		}
+
+		fmt.Printf("Your favorite food is %s with %s on top.\n", menuItemStrings[favorite], opts[0].Text)
+
+		return nil
+	})
+	return menu
+}