add go.mod and example

Readme.md

@@ -19,6 +19,8 @@ or `nil` and cast it to a pointer to the interface we want to specify: `(*Someth
 Dingo then knowns how to dereference it properly and derive the correct type `Something`.
 This is not necessary for structs, where we can just use the null value via `Something{}`.
 
+See the example folder for a complete example.
+
 ```go
 package example
 

example/application/service.go

@@ -0,0 +1,54 @@
+package application
+
+import (
+	"fmt"
+	"math/rand"
+	"strconv"
+)
+
+// TransactionLog logs information with a unique id and a message
+type TransactionLog interface {
+	Log(id, message string)
+}
+
+// CreditCardProcessor allows to auth and eventually capture an amount
+// float64 is used as an example here
+type CreditCardProcessor interface {
+	Auth(amount float64) error
+	Capture(amount float64) error
+}
+
+// Service defines our example application service
+type Service struct {
+	logger    TransactionLog
+	processor CreditCardProcessor
+}
+
+// Inject dependencies for our service
+func (s *Service) Inject(logger TransactionLog, processor CreditCardProcessor) *Service {
+	s.logger = logger
+	s.processor = processor
+	return s
+}
+
+// MakeTransaction tries to authorize and capture an amount, and logs these steps.
+func (s *Service) MakeTransaction(amount float64, message string) error {
+	id := strconv.Itoa(rand.Int())
+
+	s.logger.Log(id, fmt.Sprintf("Start transaction %q", message))
+
+	s.logger.Log(id, "Try to Auth")
+	if err := s.processor.Auth(amount); err != nil {
+		s.logger.Log(id, "Auth failed")
+		return err
+	}
+
+	s.logger.Log(id, "Try to Capture")
+	if err := s.processor.Capture(amount); err != nil {
+		s.logger.Log(id, "Capture failed")
+		return err
+	}
+
+	s.logger.Log(id, "Transaction successful")
+	return nil
+}

example/main.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"log"
+
+	"flamingo.me/dingo"
+	"flamingo.me/dingo/example/application"
+	"flamingo.me/dingo/example/paypal"
+)
+
+type stdloggerTransactionLog struct {
+	prefix string
+}
+
+var _ application.TransactionLog = new(stdloggerTransactionLog)
+
+// Log a message with the configure prefix
+func (s *stdloggerTransactionLog) Log(id, message string) {
+	log.Println(s.prefix, id, message)
+}
+
+type defaultModule struct{}
+
+// Configure the dingo injector
+func (*defaultModule) Configure(injector *dingo.Injector) {
+	injector.Bind(new(application.TransactionLog)).ToInstance(&stdloggerTransactionLog{
+		prefix: "example",
+	})
+}
+
+func main() {
+	// create a new injector and load modules
+	injector := dingo.NewInjector(
+		new(paypal.Module),
+		new(defaultModule),
+	)
+
+	// instantiate the application service
+	service := injector.GetInstance(application.Service{}).(*application.Service)
+
+	// make a transaction
+	if err := service.MakeTransaction(99.95, "test transaction"); err != nil {
+		log.Fatal(err)
+	}
+}

example/paypal/module.go

@@ -0,0 +1,14 @@
+package paypal
+
+import (
+	"flamingo.me/dingo"
+	"flamingo.me/dingo/example/application"
+)
+
+// Module configures an application to use the paypalCCProcessor for CreditCardProcessing
+type Module struct{}
+
+// Configure dependency injection
+func (m *Module) Configure(injector *dingo.Injector) {
+	injector.Bind(new(application.CreditCardProcessor)).To(new(paypalCCProcessor))
+}

example/paypal/processor.go

@@ -0,0 +1,21 @@
+package paypal
+
+import (
+	"log"
+
+	"flamingo.me/dingo/example/application"
+)
+
+type paypalCCProcessor struct{}
+
+var _ application.CreditCardProcessor = new(paypalCCProcessor)
+
+func (*paypalCCProcessor) Auth(amount float64) error {
+	log.Printf("Paypal: Auth: %v", amount)
+	return nil
+}
+
+func (*paypalCCProcessor) Capture(amount float64) error {
+	log.Printf("Paypal: Capture: %v", amount)
+	return nil
+}

go.mod

@@ -0,0 +1,9 @@
+module flamingo.me/dingo
+
+go 1.12
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.2.2
+)

go.sum

@@ -0,0 +1,6 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=