golang架构设计开闭原则手写实现

package open_close
type ICourse interface {
    ID() int
    Name() string
    Price() float64
}

package open_close
type GolangCourse struct {
    iID int
    sName string
    fPrice float64
}
func NewGolangCourse(id int, name string, price float64) ICourse {
    return &GolangCourse{
        iID: id,
        sName: name,
        fPrice: price,
    }
}
func (me *GolangCourse) ID() int {
    return me.iID
}
func (me *GolangCourse) Name() string {
    return me.sName
}
func (me *GolangCourse) Price() float64 {
    return me.fPrice
}

package open_close
type IDiscount interface {
    Discount() float64
}

package open_close
type DiscountedGolangCourse struct {
    GolangCourse
    fDiscount float64
}
func NewDiscountedGolangCourse(id int, name string, price float64, discount float64) ICourse {
    return &DiscountedGolangCourse{
        GolangCourse: GolangCourse{
            iID:    id,
            sName:  name,
            fPrice: price,
        },
        fDiscount : discount,
    }
}
// implements IDiscount.Discount
func (me *DiscountedGolangCourse) Discount() float64 {
    return me.fDiscount
}
// overwrite ICourse.Price
func (me *DiscountedGolangCourse) Price() float64 {
    return me.fDiscount * me.GolangCourse.Price()
}

package main
import (
    "testing"
)
import (ocp "learning/gooop/principles/open_close")
func Test_open_close(t  *testing.T) {
    fnShowCourse := func(it ocp.ICourse) {
        t.Logf("id=%v, name=%v, price=%v\n", it.ID(), it.Name(), it.Price())
    }
    c1 := ocp.NewGolangCourse(1, "golang课程", 100)
    fnShowCourse(c1)
    c2 := ocp.NewDiscountedGolangCourse(2, "golang优惠课程", 100, 0.6)
    fnShowCourse(c2)
}

$> go test -v main/open_close_test.go 
=== RUN   Test_open_close
    open_close_test.go:10: id=1, name=golang课程, price=100
    open_close_test.go:10: id=2, name=golang优惠课程, price=60
--- PASS: Test_open_close (0.00s)
PASS
ok      command-line-arguments  0.001s