cast

Overview ¶

Package cast provides safe, generic alternatives to Go's standard type assertion. It simplifies type conversions by offering convenient, single-expression functions that gracefully handle the `value, ok` idiom, avoiding panics on incorrect type assertions.

Usage ¶

A common use case is safely dispatching events of different types:

type UserCreatedEvent struct{ UserID int }
type OrderPlacedEvent struct{ OrderID string }

func HandleEvent(event any) {
	if u, ok := cast.As[UserCreatedEvent](event); ok {
		processUserCreated(u)
		return
	}
	if o, ok := cast.As[OrderPlacedEvent](event); ok {
		processOrderPlaced(o)
		return
	}
	// Optionally, handle or log unknown event types.
}

Another simple example:

var myVal any = "hello world"

// Safely cast `myVal` to a string.
if str, ok := cast.As[string](myVal); ok {
	fmt.Printf("Successfully casted to string: %s\n", str)
}

// Attempt to cast to an incorrect type.
if _, ok := cast.As[int](myVal); !ok {
	fmt.Println("Failed to cast to int, as expected.")
}

For more details on specific functions, refer to the function documentation.