add factory pattern

Author: tensor-programming

factory/factory/factory.go

@@ -0,0 +1,133 @@
+package factory
+
+import "fmt"
+
+type (
+	mongoDB struct {
+		database map[string]string
+	}
+
+	sqlite struct {
+		database map[string]string
+	}
+
+	file struct {
+		name    string
+		content string
+	}
+
+	ntfs struct {
+		files map[string]file
+	}
+
+	ext4 struct {
+		files map[string]file
+	}
+
+	FileSystem interface {
+		CreateFile(string)
+		FindFile(string) file
+	}
+
+	Database interface {
+		GetData(string) string
+		PutData(string, string)
+	}
+
+	Factory func(string) interface{}
+)
+
+func (mdb mongoDB) GetData(query string) string {
+	if _, ok := mdb.database[query]; !ok {
+		return ""
+	}
+
+	fmt.Println("MongoDB")
+	return mdb.database[query]
+}
+
+func (sql sqlite) GetData(query string) string {
+	if _, ok := sql.database[query]; !ok {
+		return ""
+	}
+
+	fmt.Println("Sqlite")
+	return sql.database[query]
+}
+
+func (mdb mongoDB) PutData(query string, data string) {
+	mdb.database[query] = data
+}
+
+func (sql sqlite) PutData(query string, data string) {
+	sql.database[query] = data
+}
+
+func (ntfs ntfs) CreateFile(path string) {
+	file := file{content: "NTFS file", name: path}
+	ntfs.files[path] = file
+	fmt.Println("NTFS")
+}
+
+func (ext ext4) CreateFile(path string) {
+	file := file{content: "EXT4 file", name: path}
+	ext.files[path] = file
+	fmt.Println("EXT4")
+}
+
+func (ntfs ntfs) FindFile(path string) file {
+	if _, ok := ntfs.files[path]; !ok {
+		return file{}
+	}
+
+	return ntfs.files[path]
+}
+
+func (ext ext4) FindFile(path string) file {
+	if _, ok := ext.files[path]; !ok {
+		return file{}
+	}
+
+	return ext.files[path]
+}
+
+func FilesystemFactory(env string) interface{} {
+	switch env {
+	case "production":
+		return ntfs{
+			files: make(map[string]file),
+		}
+	case "development":
+		return ext4{
+			files: make(map[string]file),
+		}
+	default:
+		return nil
+	}
+}
+
+func DatabaseFactory(env string) interface{} {
+	switch env {
+	case "production":
+		return mongoDB{
+			database: make(map[string]string),
+		}
+	case "development":
+		return sqlite{
+			database: make(map[string]string),
+		}
+	default:
+		return nil
+	}
+}
+
+func AbstractFactory(fact string) Factory {
+	switch fact {
+	case "database":
+		return DatabaseFactory
+	case "filesystem":
+		return FilesystemFactory
+	default:
+		return nil
+	}
+}

factory/main.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"fmt"
+	"reflect"
+
+	"github.com/tensor-programming/pattern-tutorial/factory"
+)
+
+func SetupConstructors(env string) (factory.Database, factory.FileSystem) {
+	fs := factory.AbstractFactory("filesystem")
+	db := factory.AbstractFactory("database")
+
+	return db(env).(factory.Database),
+		fs(env).(factory.FileSystem)
+}
+
+func main() {
+	env1 := "production"
+	env2 := "development"
+
+	db1, fs1 := SetupConstructors(env1)
+	db2, fs2 := SetupConstructors(env2)
+
+	// db1 := factory.DatabaseFactory(env1)
+	// db2 := factory.DatabaseFactory(env2)
+
+	db1.PutData("test", "this is mongodb")
+	fmt.Println(db1.GetData("test"))
+
+	db2.PutData("test", "this is sqlite")
+	fmt.Println(db2.GetData("test"))
+
+	fs1.CreateFile("../example/testntfs.txt")
+	fmt.Println(fs1.FindFile("../example/testntfs.txt"))
+
+	fs2.CreateFile("../example/testext4.txt")
+	fmt.Println(fs2.FindFile("../example/testext4.txt"))
+
+	fmt.Println(reflect.TypeOf(db1).Name())
+	fmt.Println(reflect.TypeOf(&db1).Elem())
+	fmt.Println(reflect.TypeOf(db2).Name())
+	fmt.Println(reflect.TypeOf(&db2).Elem())
+
+	fmt.Println(reflect.TypeOf(fs1).Name())
+	fmt.Println(reflect.TypeOf(&fs1).Elem())
+	fmt.Println(reflect.TypeOf(fs2).Name())
+	fmt.Println(reflect.TypeOf(&fs2).Elem())
+}