工厂方法模式使用子类的方式延迟生成对象到子类中实现。
Go中不存在继承 所以使用匿名组合来实现
查看全部设计模式：http://www.golang.ren/article/6477
factorymethod.go
package factorymethod
//Operator 是被封装的实际类接口
type Operator interface {
SetA(int)
SetB(int)
Result() int
}
//OperatorFactory 是工厂接口
type OperatorFactory interface {
Create() Operator
}
//OperatorBase 是Operator 接口实现的基类，封装公用方法
type OperatorBase struct {
a, b int
}
//SetA 设置 A
func (o *OperatorBase) SetA(a int) {
o.a = a
}
//SetB 设置 B
func (o *OperatorBase) SetB(b int) {
o.b = b
}
//PlusOperatorFactory 是 PlusOperator 的工厂类
type PlusOperatorFactory struct{}
func (PlusOperatorFactory) Create() Operator {
return &PlusOperator{
OperatorBase: &OperatorBase{},
}
}
//PlusOperator Operator 的实际加法实现
type PlusOperator struct {
*OperatorBase
}
//Result 获取结果
func (o PlusOperator) Result() int {
return o.a + o.b
}
//MinusOperatorFactory 是 MinusOperator 的工厂类
type MinusOperatorFactory struct{}
func (MinusOperatorFactory) Create() Operator {
return &MinusOperator{
OperatorBase: &OperatorBase{},
}
}
//MinusOperator Operator 的实际减法实现
type MinusOperator struct {
*OperatorBase
}
//Result 获取结果
func (o MinusOperator) Result() int {
return o.a - o.b
}
factorymethod_test.go
package factorymethod
import "testing"
func compute(factory OperatorFactory, a, b int) int {
op := factory.Create()
op.SetA(a)
op.SetB(b)
return op.Result()
}
func TestOperator(t *testing.T) {
var (
factory OperatorFactory
)
factory = PlusOperatorFactory{}
if compute(factory, 1, 2) != 3 {
t.Fatal("error with factory method pattern")
}
factory = MinusOperatorFactory{}
if compute(factory, 4, 2) != 2 {
t.Fatal("error with factory method pattern")
}
}
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