Need help in in implementing a method on an interface

[rickyu...@gmail.com]

Hello all,

I am golang beginner. And I have a problem with interfaces. 

Here is the problem where I have one main package with has an Interface I. and multiple sub packages each implementing interface I. So I have a method which is exactly the same for all sub packages. Is there a way I can implement this method for I. 

package main

type I interface {

F1()

GenericMethod()            // Is there a way I can implement it on I since its the same in all packages?

}

package p1

type P1data struct  {}

(x *P1data) F1()

(x *P1data) GenericMethod()

package p2

type P2data struct  {}

(x *P2data) F1()

(x *P2data) GenericMethod()

under the main package.

for each data in sub packages do data.F1 and data.GenericMethod().

Now I don't want to implement GenericMethod for all packages. Since its the same.So can I implement GenericMethod on I (I know this is not possible). But how can do something like this?

-Thanks

[alex....@gmail.com]

If GenericMethod is truly the same, as in not even using the struct fields from P1data/P2data then there is a way. You just need to create a new struct type in package main that implements GenericMethod and then in packages p1 and p2 you embed the struct and thus expose the method.

package main


import (
 "fmt"
)

type I interface {
 F1()
 GenericMethod()
}

type Generic struct{}


func (*Generic) GenericMethod() {
 fmt.Printf("Hello World")
}

//package p1
type P1data struct {
 Generic
}


func (x *P1data) F1() {}


func main() {
 i := I(&P1data{})
 i.GenericMethod()
}

[rickyu...@gmail.com]

Hi Alex,

Thanks for the response. Apologies for the confusion. The Generic method indeed uses struct fields from P1data/P2data struct(they are all same structs). Can I still achieve this? From the below. GenericMethod should read name field from structs.

//package p1
type P1data struct {

 name string
}

//package p2
type P1data struct {
 name string
}

-Thanks

[alex....@gmail.com]

Then just do 

type Generic struct{
 name string
}


func (*Generic) GenericMethod() {
 fmt.Printf(name)
}

If you want to access name from p1

type Generic struct{
 Name string
}


func (g *Generic) GenericMethod() {
 fmt.Printf(g.Name)
}

//package p1
func (x *P1data) F1() {
 x.Generic.Name = "asdf"
}