Merge branch 'master' of https://github.com/ardanlabs/gotraining

Author: ardan-bkennedy

topics/go/language/interfaces/README.md

@@ -35,8 +35,8 @@ _"The empty interface says nothing." - Rob Pike
 [Method Sets](example2/example2.go) ([Go Playground](https://play.golang.org/p/N50ocjUekf3))  
 [Address Of Value](example3/example3.go) ([Go Playground](https://play.golang.org/p/w981JSUcVZ2))  
 [Storage By Value](example4/example4.go) ([Go Playground](https://play.golang.org/p/6U232Ue_BY0))  
-[Type Assertions](example5/example5.go) ([Go Playground](https://play.golang.org/p/YPBuhSxK6Ia))  
-[Conditional Type Assertions](example6/example6.go) ([Go Playground](https://play.golang.org/p/Wwyg9dNYkj_l))  
+[Type Assertions](example5/example5.go) ([Go Playground](https://play.golang.org/p/f47JMTj2eId))  
+[Conditional Type Assertions](example6/example6.go) ([Go Playground](https://play.golang.org/p/9fYc5RyyvVG))  
 [The Empty Interface and Type Switches](example7/example7.go) ([Go Playground](https://play.golang.org/p/iyDfKCIQ4S9))  
 
 ## Advanced Code Review

topics/go/language/interfaces/example5/example5.go

@@ -20,22 +20,22 @@ type finder interface {
 	find(id int) (*user, error)
 }
 
-// userDB defines a database we will access.
-type userDB struct {
+// userSVC is a service for dealing with users.
+type userSVC struct {
 	host string
 }
 
 // find implements the finder interface using pointer semantics.
-func (db *userDB) find(id int) (*user, error) {
+func (*userSVC) find(id int) (*user, error) {
 	return &user{id: id, name: "Anna Walker"}, nil
 }
 
 func main() {
-	db := userDB{
+	svc := userSVC{
 		host: "localhost:3434",
 	}
 
-	if err := run(&db); err != nil {
+	if err := run(&svc); err != nil {
 		log.Fatal(err)
 	}
 }
@@ -54,16 +54,16 @@ func run(f finder) error {
 	// you really need to get to the concrete value stored inside
 	// the interface?
 
-	// Can you access the "host" field from the concrete userDB type pointer
+	// Can you access the "host" field from the concrete userSVC type pointer
 	// that is stored inside this interface variable? No, not directly.
 	// All you know is the data has a method named "find".
 	// ./example5.go:61:26: f.host undefined (type finder has no field or method host)
 	log.Println("queried", f.host)
 
-	// You can use a type assertion to get a copy of the userDB pointer
+	// You can use a type assertion to get a copy of the userSVC pointer
 	// that is stored inside the interface.
-	db := f.(*userDB)
-	log.Println("queried", db.host)
+	svc := f.(*userSVC)
+	log.Println("queried", svc.host)
 
 	return nil
 }

topics/go/language/interfaces/example6/example6.go

@@ -20,28 +20,28 @@ type finder interface {
 	find(id int) (*user, error)
 }
 
-// userDB defines a database we will access.
-type userDB struct {
+// userSVC is a service for dealing with users.
+type userSVC struct {
 	host string
 }
 
 // find implements the finder interface using pointer semantics.
-func (db *userDB) find(id int) (*user, error) {
+func (*userSVC) find(id int) (*user, error) {
 	return &user{id: id, name: "Anna Walker"}, nil
 }
 
-// mockDB defines a mock database we will access.
-type mockDB struct{}
+// mockSVC defines a mock service we will access.
+type mockSVC struct{}
 
 // find implements the finder interface using pointer semantics.
-func (db *mockDB) find(id int) (*user, error) {
+func (*mockSVC) find(id int) (*user, error) {
 	return &user{id: id, name: "Jacob Walker"}, nil
 }
 
 func main() {
-	var db mockDB
+	var svc mockSVC
 
-	if err := run(&db); err != nil {
+	if err := run(&svc); err != nil {
 		log.Fatal(err)
 	}
 }
@@ -54,10 +54,10 @@ func run(f finder) error {
 	fmt.Printf("Found user %+v\n", u)
 
 	// If the concrete type value stored inside the interface value is of the
-	// type *userDB, then "ok" will be true and "db" will be a copy of the
+	// type *userSVC, then "ok" will be true and "svc" will be a copy of the
 	// pointer stored inside the interface.
-	if db, ok := f.(*userDB); ok {
-		log.Println("queried", db.host)
+	if svc, ok := f.(*userSVC); ok {
+		log.Println("queried", svc.host)
 	}
 
 	return nil