duanhe8280 2017-09-19 17:51
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在golang中实现接口给方法有指针接收器

am working in Golang, am trying to use interfaces to agroup a set of structs that are using a similar method. Briefly I have this:

type Person interface {
    BasicInfo() MemberBasicInfo
}

type MemberBasicInfo struct {
    ID                         uint       
    MemberFirstName            string     
    MemberNickname             string     
    MemberEmail                string    
}

Then, the structs that should work as interfaces:

func (member *Member) BasicInfo() MemberBasicInfo{
    return MemberBasicInfo{
        ID: member.ID,
        ...other mapping here...
    }
}

func (user *User) BasicInfo() MemberBasicInfo{
    return MemberBasicInfo{
        ID: uint(user.ID),
        ...other mapping here...
    }
}

cannot use memberData (type Member) as type Member.Person in return argument: Member does not implement Person (BasicInfo method has pointer receiver)
cannot use memberData (type User) as type Person in return argument: User does not implement Person (BasicInfo method has pointer receiver)

What am I missing? or what am I doing wrong?

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2条回答 默认 最新

  • douhan9191 2017-09-19 18:07
    关注

    If your interface is declared like this:

    type Person interface {
        BasicInfo() MemberBasicInfo
    }
    

    Then any type that implements a BasicInfo() MemberBasicInfo will fulfil the interface.

    In your case, you then created this method:

    func (member *Member) BasicInfo() MemberBasicInfo
    

    That means that the type *Member fulfils the interface.

    But.. note the * there. Member does not implement the interface, it is *Member who does.

    So when trying to assign a type to an interface variable, make sure to use a pointer and not a direct value.

    This should work:

    var p Person
    p = &Member{}
    

    But this will not:

    var p Person
    p = Member{}
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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