Function as a Field in Golang Structure

A structure or struct in Golang is a user-defined type, which allows us to create a group of elements of different types into a single unit. Any real-world entity which has some set of properties or fields can be represented as a struct. As we know that in Go language function is also a user-defined type so, you are allowed to create a function field in the Go structure. You can also create a function field in the Go structure using an anonymous function as shown in Example 2.

Syntax:

type function_name func()
type strcut_name struct{
  var_name  function_name
}

Let us discuss this concept with the help of the examples:

Example 1:

// Go program to illustrate the function
// as a field in Go structure
package main

import "fmt"

// Finalsalary of function type
type Finalsalary func(int, int) int

// Creating structure
type Author struct {
    name      string
    language  string
    Marticles int
    Pay       int

    // Function as a field
    salary Finalsalary
}

// Main method
func main() {

    // Initializing the fields
    // of the structure
    result := Author{
        name:      "Sonia",
        language:  "Java",
        Marticles: 120,
        Pay:       500,
        salary: func(Ma int, pay int) int {
            return Ma * pay
        },
    }

    // Display values
    fmt.Println("Author's Name: ", result.name)
    fmt.Println("Language: ", result.language)
    fmt.Println("Total number of articles published in May: ", result.Marticles)
    fmt.Println("Per article pay: ", result.Pay)
    fmt.Println("Total salary: ", result.salary(result.Marticles, result.Pay))
}

Output:

Author's Name:  Sonia
Language:  Java
Total number of articles published in May:  120
Per article pay:  500
Total salary:  60000

Example 2:

// Go program to illustrate the function
// as a field in Go structure
// Using anonymous function
package main

import "fmt"

// Creating structure
type Author struct {
    name      string
    language  string
    Tarticles int
    Particles int
    Pending   func(int, int) int
}

// Main method
func main() {

    // Initializing the fields
    // of the structure
    result := Author{
        name:      "Sonia",
        language:  "Java",
        Tarticles: 340,
        Particles: 259,
        Pending: func(Ta int, Pa int) int {
            return Ta - Pa
        },
    }

    // Display values
    fmt.Println("Author's Name: ", result.name)
    fmt.Println("Language: ", result.language)
    fmt.Println("Total number of articles: ", result.Tarticles)

    fmt.Println("Total number of published articles: ",
                                      result.Particles)

    fmt.Println("Pending articles: ", result.Pending(result.Tarticles,
                                                   result.Particles))
}

Output:

Author's Name:  Sonia
Language:  Java
Total number of articles:  340
Total number of published articles:  259
Pending articles:  81