Using enum instead strings

[suntong]

The current approach of fsm is to use string to represent stages:

fsm/examples/simple.go

Lines 14 to 19 in e668a85

	fsm := fsm.NewFSM(
	"closed",
	fsm.Events{
	{Name: "open", Src: []string{"closed"}, Dst: "open"},
	{Name: "close", Src: []string{"open"}, Dst: "closed"},
	},

which is kind of error prone. These strings should better be replace with enum values instead, to

• save space, and most importantly
• allow compiler to do spellcheck for us

Like this:

type myFSM int

const (
	Init myFSM = iota
	Open
	Progress
	Close = Stop
)

For further details, check out https://pkg.go.dev/golang.org/x/tools/cmd/stringer

Please consider.