package state import "fmt" type Week interface { Today() Next(*DayContext) } type DayContext struct { today Week } func NewDayContext() *DayContext { return &DayContext{ today: &Sunday{}, } } func (d *DayContext) Today() { d.today.Today() } func (d *DayContext) Next() { d.today.Next(d) } type Sunday struct{} func (*Sunday) Today() { fmt.Printf("Sunday\n") } func (*Sunday) Next(ctx *DayContext) { ctx.today = &Monday{} } type Monday struct{} func (*Monday) Today() { fmt.Printf("Monday\n") } func (*Monday) Next(ctx *DayContext) { ctx.today = &Tuesday{} } type Tuesday struct{} func (*Tuesday) Today() { fmt.Printf("Tuesday\n") } func (*Tuesday) Next(ctx *DayContext) { ctx.today = &Wednesday{} } type Wednesday struct{} func (*Wednesday) Today() { fmt.Printf("Wednesday\n") } func (*Wednesday) Next(ctx *DayContext) { ctx.today = &Thursday{} } type Thursday struct{} func (*Thursday) Today() { fmt.Printf("Thursday\n") } func (*Thursday) Next(ctx *DayContext) { ctx.today = &Friday{} } type Friday struct{} func (*Friday) Today() { fmt.Printf("Friday\n") } func (*Friday) Next(ctx *DayContext) { ctx.today = &Saturday{} } type Saturday struct{} func (*Saturday) Today() { fmt.Printf("Saturday\n") } func (*Saturday) Next(ctx *DayContext) { ctx.today = &Sunday{} }