Golang 多态参数和返回

Question

假设我有函数:

func ToModelList(cats *[]*Cat) *[]*CatModel {
    list := *cats
    newModelList := []*CatModel{}
    for i := range list {
        obj := obj[i]
        newModelList = append(newModelList, obj.ToModel())
    }
    return &newModelList
}

func ToModelList(dogs *[]*Dog) *[]*DogModel {
    list := *dogs
    newModelList := []*DogModel{}
    for i := range list {
        obj := obj[i]
        newModelList = append(newModelList, obj.ToModel())
    }
    return &newModelList
}

有没有办法将这两者结合起来，这样我就可以做类似的事情

func ToModelList(objs *[]*interface{}) *[]*interface{} {
    list := *objs
    // figure out what type struct type objs/list are
    newModelList := []*interface{}
    // type cast newModelList to the correct array struct type
    for i := range list {
        obj := obj[i]
        // type cast obj based on objs's type
        newModelList = append(newModelList, obj.ToModel())
    }
    return &newModelList
}

Answer 1

首先，slice已经是一个引用，除非你需要改变slice本身，否则不需要将它作为一个指针来传递。其次，interface{} 可以是对象或指向对象的指针。您不需要 *interface{}。

我不确定你想要达到什么目的，但你可以这样做:

package main

// Interface for Cat, Dog
type Object interface {
        ToModel() Model
}

// Interface for CatModel, DogModel
type Model interface {
        Name() string
}

type Cat struct {
        name string
}

func (c *Cat) ToModel() Model {
        return &CatModel{
                cat: c,
        }
}

type CatModel struct {
        cat *Cat
}

func (c *CatModel) Name() string {
        return c.cat.name
}

type Dog struct {
        name string
}

func (d *Dog) ToModel() Model {
        return &DogModel{
                dog: d,
        }
}

type DogModel struct {
        dog *Dog
}

func (d *DogModel) Name() string {
        return d.dog.name
}

func ToModelList(objs []Object) []Model {
        newModelList := []Model{}
        for _, obj := range objs {
                newModelList = append(newModelList, obj.ToModel())
        }
        return newModelList
}

func main() {
        cats := []Object{
                &Cat{name: "felix"},
                &Cat{name: "leo"},
                &Dog{name: "octave"},
        }
        modelList := ToModelList(cats)

        for _, model := range modelList {
                println(model.Name())
        }
}

您为您的猫、狗等和您的模型定义接口(interface)。然后，您可以根据需要实现它们，执行 ToModelList() 非常简单。