Behaviors

type Behavior func(ctx *ReceiveContext)

package main

import (
    "context"
    "fmt"
    "time"

    "github.com/tochemey/goakt/v4/actor"
)

// Message types
type Login struct{ User string }
type Logout struct{}
type Transfer struct {
    To     string
    Amount int64
}

type Confirm struct{}
type Cancel struct{}

type AccountActor struct {
    balance         int64
    pendingTransfer *Transfer // stored when awaiting confirmation
}

func (a *AccountActor) PreStart(ctx *actor.Context) error { return nil }
func (a *AccountActor) PostStop(ctx *actor.Context) error  { return nil }

func (a *AccountActor) Receive(ctx *actor.ReceiveContext) {
    switch ctx.Message().(type) {
    case *Login:
        ctx.Become(a.Authenticated)
    default:
        ctx.Unhandled()
    }
}

func (a *AccountActor) Authenticated(ctx *actor.ReceiveContext) {
    switch msg := ctx.Message().(type) {
    case *Logout:
        ctx.UnBecome()
    case *Transfer:
        a.pendingTransfer = msg
        ctx.BecomeStacked(a.ConfirmTransfer)
    default:
        ctx.Unhandled()
    }
}

func (a *AccountActor) ConfirmTransfer(ctx *actor.ReceiveContext) {
    switch ctx.Message().(type) {
    case *Confirm:
        if a.pendingTransfer != nil {
            a.balance -= a.pendingTransfer.Amount
            a.pendingTransfer = nil
        }
        ctx.UnBecomeStacked()
    case *Cancel:
        a.pendingTransfer = nil
        ctx.UnBecomeStacked()
    default:
        ctx.Unhandled()
    }
}

func main() {
    ctx := context.Background()
    system, err := actor.NewActorSystem("behaviors-demo",
        actor.WithLoggingDisabled(),
        actor.WithActorInitMaxRetries(3))
    if err != nil {
        panic(err)
    }
    if err := system.Start(ctx); err != nil {
        panic(err)
    }
    defer system.Stop(ctx)

    acc := &AccountActor{balance: 1000}
    pid, err := system.Spawn(ctx, "account", acc)
    if err != nil {
        panic(err)
    }

    // Login -> switches to Authenticated
    _ = actor.Tell(ctx, pid, &Login{User: "alice"})

    // Transfer -> pushes ConfirmTransfer on stack
    _ = actor.Tell(ctx, pid, &Transfer{To: "bob", Amount: 50})

    // Confirm -> pops ConfirmTransfer, executes transfer
    _ = actor.Tell(ctx, pid, &Confirm{})

    fmt.Println("Done. Balance:", acc.balance) // 950
}