[go設計模式]工廠方法模式
簡單工廠就是生產整個計算器，而工廠方法只生產計算器的一部分；
原有的簡單工廠可以生’+’ ‘-‘ ‘*’ ‘/’ ;但是如果添加新的部件’%’，廠房就
需要擴充、修改很可以會影響原來部件的正常生產，這就違背了開放封閉原則；
而工廠方法則不存在這個問題；我新開一個工廠專門生產’%’就可以了。
package main
import (
"fmt"
)
type Operation interface {
Exe(int, int) int
}
type FactoryAdd struct{}
type OperationAdd struct{}
func (this *FactoryAdd) Create() Operation {
return &OperationAdd{}
}
func (this *OperationAdd) Exe(a int, b int) int {
return a + b
}
type FactorySub struct{}
type OperationSub struct{}
func (this *FactorySub) Create() Operation {
return &OperationSub{}
}
func (this *OperationSub) Exe(a int, b int) int {
return a - b
}
type FactoryMul struct{}
type OperationMul struct{}
func (this *FactoryMul) Create() Operation {
return &OperationMul{}
}
func (this *OperationMul) Exe(a int, b int) int {
return a * b
}
type FactoryDiv struct{}
type OperationDiv struct{}
func (this *FactoryDiv) Create() Operation {
return &OperationDiv{}
}
func (this *OperationDiv) Exe(a int, b int) int {
return a / b
}
// 新增一個"%"操作，不影響原來的代碼，符合開放封閉原則
type FactoryMod struct{}
type OperationMod struct{}
func (this *FactoryMod) Create() Operation {
return &OperationMod{}
}
func (this *OperationMod) Exe(a int, b int) int {
return a % b
}
func main() {
fmt.Println(
(&FactoryAdd{}).Create().Exe(10, 5),
(&FactorySub{}).Create().Exe(10, 5),
(&FactoryMul{}).Create().Exe(10, 5),
(&FactoryDiv{}).Create().Exe(10, 5),
(&FactoryMod{}).Create().Exe(10, 5))
}
輸出結果：
15 5 50 2 0
