replaced Database constructors with init functions

db.go

@@ -8,36 +8,60 @@ import (
 
 type Database struct {
 	db    *sql.DB
-	closefuncs []func() error
+	stmts map[string]*sql.Stmt
 }
 
-func NewDatabase(conn *sql.DB) *Database {
-	return &Database{
+func InitDatabase(database *Database, conn *sql.DB) {
+	panicOnNil(database)
+
+	*database = Database{
 		db:    conn,
-		closefuncs: make([]func() error, 0),
+		stmts: map[string]*sql.Stmt{},
 	}
+	database.init()
 }
 
-func NewMysqlDatabase(host string, port uint16, user, pass, db string) *Database {
+func InitMysqlDatabase(database *Database, host string, port uint16, user, pass, db string) {
+	panicOnNil(database)
+
 	conn, err := sql.Open("mysql", connString(host, port, user, pass, db))
 	if err != nil {
 		panic(err)
 	}
-	return NewDatabase(conn)
+
+	InitDatabase(database, conn)
 }
 
-func (db *Database) prepare(query string) *sql.Stmt {
-	s, err := db.db.Prepare(query)
+func panicOnNil(database *Database) {
+	if database == nil {
+		panic("database is nil. initialize database variable with new()")
+	}
+}
+
+func (db *Database) init() {
+	for _, globalQuery := range globalStmts {
+		if db == globalQuery.db {
+			db.stmt(globalQuery.query)
+		}
+	}
+}
+
+func (db *Database) stmt(query string) *sql.Stmt {
+	if stmt, ok := db.stmts[query]; ok {
+		return stmt
+	}
+
+	stmt, err := db.db.Prepare(query)
 	if err != nil {
 		panic(err)
 	}
-	db.closefuncs = append(db.closefuncs, s.Close)
-	return s
+	db.stmts[query] = stmt
+	return stmt
 }
 
 func (db *Database) Close() error {
-	for _, close := range db.closefuncs {
-		close()
+	for _, stmt := range db.stmts {
+		stmt.Close()
 	}
 	return db.db.Close()
 }

db_test.go

@@ -9,33 +9,31 @@ import (
 	_ "github.com/go-sql-driver/mysql"
 )
 
+var TestDatabase *Database //= new(Database)
+
 type User struct {
 	Name string
 	Hash []byte
 	Salt string
 }
 
-func UserDecoder(u *User, decode ScanFunc) error {
-	return decode(&u.Name, &u.Hash, &u.Salt)
+func ScanUserPkFirst(u *User, encode ScanFunc) error {
+	return encode(&u.Name, &u.Hash, &u.Salt)
 }
 
-func InsertUserEncoder(u *User, encode ScanFunc) error {
-	return encode(u.Name, u.Hash, u.Salt)
+func ScanUserPkLast(u *User, encode ScanFunc) error {
+	return encode(&u.Hash, &u.Salt, &u.Name)
 }
 
-func UpdateUserByNameEncoder(u *User, encode ScanFunc) error {
-	return encode(u.Salt, u.Name)
-}
+var (
+	InsertUser    = Insert(TestDatabase, "INSERT INTO users VALUES (?, ?, ?)", ScanUserPkFirst)
+	UpdateUser    = Update(TestDatabase, "UPDATE users SET hash = ?, salt = ? WHERE name = ?", ScanUserPkLast)
+	GetUserByName = QueryOne(TestDatabase, "SELECT * FROM users WHERE namea = ?", ScanUserPkFirst)
+)
 
 func TestDB(t *testing.T) {
-	db := NewMysqlDatabase("ip", 3306, "username", "password", "database")
-	defer db.Close()
-
-	insertUser := Insert(db, "INSERT INTO users VALUES (?, ?, ?)", InsertUserEncoder)
-
-	updateUser := Update(db, "UPDATE users SET salt = ? WHERE name = ?", UpdateUserByNameEncoder)
-
-	getUsers := QueryMany(db, "SELECT * FROM users WHERE name = ?", UserDecoder)
+	InitMysqlDatabase(TestDatabase, "ip", 3306, "username", "password", "database")
+	defer TestDatabase.Close()
 
 	pw := sha512.Sum512([]byte("weiter"))
 	timon := &User{
@@ -43,13 +41,11 @@ func TestDB(t *testing.T) {
 		Hash: pw[:],
 		Salt: "salt",
 	}
-	fmt.Println("insert:", insertUser(timon))
+	fmt.Println("insert:", InsertUser(timon))
 
 	timon.Hash = []byte("asd")
-	fmt.Println("update:", updateUser(timon))
+	fmt.Println("update:", UpdateUser(timon))
 
-	for user := range getUsers("tordarus") {
+	user := GetUserByName("tordarus")
 	fmt.Printf("name: \"%s\" | hash: \"%s\" | salt: \"%s\"\n", user.Name, hex.EncodeToString(user.Hash), user.Salt)
 }
-
-}

global_stmts.go

@@ -0,0 +1,12 @@
+package advsql
+
+type globalStmt struct {
+	db    *Database
+	query string
+}
+
+var globalStmts = []*globalStmt{}
+
+func prepareGlobal(db *Database, query string) {
+	globalStmts = append(globalStmts, &globalStmt{db, query})
+}

insert.go

@@ -1,9 +1,10 @@
 package advsql
 
 func Insert[T any](db *Database, query string, encoder func(v *T, encode ScanFunc) error) InsertFunc[T] {
-	s := db.prepare(query)
+	prepareGlobal(db, query)
 
 	return func(value *T) error {
+		s := db.stmt(query)
 		return encoder(value, func(args ...interface{}) error {
 			_, err := s.Exec(args...)
 			return err

query_many.go

@@ -10,13 +10,11 @@ func QueryMany[T any](db *Database, query string, decoder func(v *T, decode Scan
 }
 
 func QueryManyContext[T any](db *Database, query string, decoder func(v *T, decode ScanFunc) error) QueryManyContextFunc[T] {
-	s, err := db.db.Prepare(query)
-	if err != nil {
-		return nil
-	}
-	db.closefuncs = append(db.closefuncs, s.Close)
+	prepareGlobal(db, query)
 
 	return func(ctx context.Context, args ...interface{}) <-chan *T {
+		s := db.stmt(query)
+
 		out := make(chan *T, 10)
 
 		rows, err := s.QueryContext(ctx, args...)