Example for blog post: Go bits: Magic with functions

closures.go

package closures

// CustomerService has repo as a protperty
// that will be "enclosed" in the receiver methods
type CustomerService struct {
   repo CustomerRepository
}

// Register is a receiver method that will be used as a closure
func (s *CustomerService) Register(customerName string) error {
   customer := Customer{Name: customerName}

   return s.repo.Add(customer)
}

// Remove is a receiver method that will be used as a closure
func (s *CustomerService) Remove(id CustomerID) error {
   return s.repo.Delete(id)
}

// ForRegisteringCustomers is a function type
type ForRegisteringCustomers func(customerName string) error

// ForRemovingCustomers is a function type
type ForRemovingCustomers func(id CustomerID) error

// CustomerRegistrationHTTPHandler receives a closure as dependency
// which fullfulls the function type ForRegisteringCustomers
type CustomerRegistrationHTTPHandler struct {
   registerCustomer ForRegisteringCustomers
}

// CustomerRemovalHTTPHandler receives a closure as dependency
// which fullfulls the function type ForRegisteringCustomers
type CustomerRemovalHTTPHandler struct {
   removeCustomer ForRemovingCustomers
}