装饰模式使用对象组合的方式动态改变或增加对象行为。

Go语言借助于匿名组合和非入侵式接口可以很方便实现装饰模式。

使用匿名组合，在装饰器中不必显式定义转调原对象方法。

decorator.go

package decoratortype Component interface {Calc() int
}type ConcreteComponent struct{}func (*ConcreteComponent) Calc() int {return 0
}type MulDecorator struct {Componentnum int
}func WarpMulDecorator(c Component, num int) Component {return &MulDecorator{Component: c,num:       num,}
}func (d *MulDecorator) Calc() int {return d.Component.Calc() * d.num
}type AddDecorator struct {Componentnum int
}func WarpAddDecorator(c Component, num int) Component {return &AddDecorator{Component: c,num:       num,}
}func (d *AddDecorator) Calc() int {return d.Component.Calc() + d.num
}

decorator_test.go

package decoratorimport "fmt"func ExampleDecorator() {var c Component = &ConcreteComponent{}c = WarpAddDecorator(c, 10)c = WarpMulDecorator(c, 8)res := c.Calc()fmt.Printf("res %d\n", res)// Output:// res 80
}