CODEWITHSUNDEEP
gostructinterface
Aman Chourasiya
Aman Chourasiya

Reputation: 1228

Method taking interface as a parameter inside interface

I am declcaring an interface in go

type comparable interface {
GetKey() float32
Compare(comparable) int

}

and implementing this interface by creating this structure

type Note struct {
id       int
text     string
priority float32

}

func (note Note) GetKey() float32 {
return note.priority

}

func (note Note) Compare(note2 Note) int {
if note.priority < note2.priority {
    return -1
} else if note.priority > note2.priority {
    return 1
} else {
    return 0
}

}

But when I am passing note object into a function which accepts comparable interface as a parameter I am getting "Wrong type for method compare" error.

Am I missing something or doing something wrong? Please help

Thanks in advance

Upvotes: 1

Views: 335

Answers (2)

Eklavya
Eklavya

Reputation: 18410

You are not implementing comparable since you use Note in compare method not comparable. Compare(note2 Note) is not same as Compare(comparable).

Use comparable in Compare method to implement comaprable interface

func (note Note) Compare(note2 comparable) int {
    if note.GetKey()< note2.GetKey() {
        return -1
    } else if note.GetKey()> note2.GetKey() {
        return 1
    } else {
        return 0
    }
}

Upvotes: 3

Eli Bendersky
Eli Bendersky

Reputation: 273376

You declared comparable as having a method with signature Compare(comparable) int.

So func (note Note) Compare(note2 Note) ought to be func (note Note) Compare(note2 comparable), to match the interface.

Otherwise, you're not implementing the same interface. To implement comparable, your Compare method needs to take any comparable, but the one you declared for Note takes only Note, and not any comparable. It's a different method.

Here's a modified-to-work, minimal example based on your code: https://play.golang.org/p/ajH1s5gbGcQ

Upvotes: 3

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