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

    1. package main
    3. import "fmt"
    5. type Operator interface {
    6.     SetA(int)
    7.     SetB(int)
    8.     Result() int
    9. }
    12. type OperatorBase struct {
    13.     a,b int
    14. }
    16. func (o *OperatorBase)SetA(a int)  {
    17.     o.a = a
    18. }
    19. func (o *OperatorBase)SetB(b int){
    20.     o.b = b
    21. }
    23. type PlusOperator struct {
    24.     *OperatorBase
    25. }
    27. func(o PlusOperator)Result()int {
    28.     return o.a+o.b
    29. }
    31. type MinusOperator struct {
    32.     *OperatorBase
    33. }
    35. func(o MinusOperator)Result()int {
    36.     return o.a-o.b
    37. }
    40. type OperatorFactory interface {
    41.     Create() Operator
    42. }
    44. type PlusOperatorFactory struct {
    46. }
    48. func(PlusOperatorFactory)Create()Operator{
    49.     return &PlusOperator{&OperatorBase{}}
    50. }
    53. type MinusOperatorFactory struct {
    55. }
    57. func(MinusOperatorFactory)Create()Operator{
    58.     return &MinusOperator{&OperatorBase{}}
    59. }
    61. func compute(factory OperatorFactory, a, b int) int {
    62.     op := factory.Create()
    63.     op.SetA(a)
    64.     op.SetB(b)
    65.     return op.Result()
    66. }
    69. func main() {
    70.     fmt.Println(compute(PlusOperatorFactory{},2,1))
    71.     fmt.Println(compute(MinusOperatorFactory{},2,1))
    72. }