Go - How to create and initialize a struct instance based on conditions when there are multiple custom type structs with the same attributes?

Question

I'm still new to Go and am facing a situation that needs some help here.

Assume there are two types of structs with the SAME attribute list:

type PersonA struct {
 [long list of attributes...]
}

type PersonB struct {
 [same long list of attributes...]
}

And I would like to create an instance and initialize based on some conditions like below:

var smartPerson [type]

func smartAction(personType string) {
 switch personType
 case "A":
  smartPerson = PersonA{long list initialization}
 case "B":
  smartPerson = PersonB{same long list initialization}
}

fmt.Println(smartPerson)

There are two problems here:

First - 'smartPerson' needs to be the instance type ascertained in the switch statement.

Second - the 'long list initialization' is the same for all conditions, so better to avoid repetition.

Is it possible to do this in Go?

Create a third type with the long list of common fields, and have PersonA and PersonB embed that. — icza
– icza, Commented Jan 19, 2022 at 22:30

Dylan Reimerink · Accepted Answer · 2022-01-19 22:32:27Z

You can, do something like this by embedding a common struct in both PersonA and PersonB.

For example (playgound link):

package main

import "fmt"

type commonPerson struct {
    A string
    B string
    C string
}

type PersonA struct {
    commonPerson
}

func (p PersonA) String() string {
    return fmt.Sprintf("A: %s, %s, %s", p.A, p.B, p.C)
}

// This function is just here so that PersonA implements personInterface
func (p PersonA) personMarker() {}

type PersonB struct {
    commonPerson
}

func (p PersonB) String() string {
    return fmt.Sprintf("B: %s, %s, %s", p.A, p.B, p.C)
}

// This function is just here so that PersonB implements personInterface
func (p PersonB) personMarker() {}

type personInterface interface {
    personMarker()
}

var smartPerson personInterface

func smartAction(personType string) {
    common := commonPerson{
        A: "foo",
        B: "bar",
        C: "Hello World",
    }

    switch personType {
    case "A":
        smartPerson = PersonA{commonPerson: common}
    case "B":
        smartPerson = PersonB{commonPerson: common}
    }
}

func main() {
    smartAction("A")
    fmt.Println(smartPerson)
    smartAction("B")
    fmt.Println(smartPerson)
}

Outputs:

A: foo, bar, Hello World
B: foo, bar, Hello World

Collectives™ on Stack Overflow

Go - How to create and initialize a struct instance based on conditions when there are multiple custom type structs with the same attributes?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related