设计模式：Go装饰模式

设计模式：Go装饰模式

结构型模式

1. 简介

装饰模式向一个现有对象添加新功能或修改原有功能，同时又不改变其原有结构。

优点

1. 不修改原有对象添加或修改原有功能。

缺点

1. 多层装饰会大幅度提高代码复杂度。

2. UML

3. 演示

3.1. 文件树型图

decorator
├── calc.go
├── calculator.go
├── decorator.go
├── decorator_test.go
└── go.mod

3.2. 代码

calculator.go

package decorator

// 计算器接口
type Calculator interface {
	Add(a, b int) int
	Minus(a, b int) int
}

calc.go

package decorator

// 计算器实现
type Calc struct {
}

func (c Calc) Add(a, b int) int {
	return a + b
}

func (c Calc) Minus(a, b int) int {
	return a - b
}

decorator.go

package decorator

import "math"

// 装饰
type CalcDecorator struct {
	Calculator
}

func (c CalcDecorator) Minus(a, b int) int {
	return int(math.Abs(float64(c.Calculator.Minus(a, b))))
}

func (c CalcDecorator) Multiply(a, b int) int {
	return a * b
}

func (c CalcDecorator) Division(a, b int) int {
	return a / b
}

decorator_test.go

package decorator

import (
	"testing"
)

func TestDecorator(t *testing.T) {
	var c Calculator = &Calc{}
	calcDecorator := &CalcDecorator{c}
	t.Log(calcDecorator.Add(1, 2))
	t.Log(calcDecorator.Minus(1, 2))
	t.Log(calcDecorator.Multiply(1, 2))
	t.Log(calcDecorator.Division(1, 2))
}

3.3. 测试

=== RUN   TestDecorator
    TestDecorator: decorator_test.go:10: 3
    TestDecorator: decorator_test.go:11: 1
    TestDecorator: decorator_test.go:12: 2
    TestDecorator: decorator_test.go:13: 0
--- PASS: TestDecorator (0.00s)
PASS

4. 参考

• 装饰器模式