Behavioral Patterns in Go

1. Strategy Pattern (Pluggable Payment Processing)

package strategy

// PaymentStrategy defines the interface for payment strategies
type PaymentStrategy interface {
    Pay(amount float64) string
}

2. Observer Pattern (Event Broadcasting)

package observer

// FitnessDataSubject defines the interface for the subject
type FitnessDataSubject interface {
    RegisterObserver(observer FitnessDataObserver)
    RemoveObserver(observer FitnessDataObserver)
    NotifyObservers()
}