Struct Embedding

Embedding puts a type into a struct without giving it a separate explicit field name, enabling promoted field and method selectors.

With type Employee struct { Person; Role string }, the embedded Person is still a real field accessible as employee.Person. Its fields can also be accessed through promoted selectors such as employee.Name when unambiguous.

Embedding is composition, not subclass inheritance. It does not make Employee a subtype of Person, and promoted methods follow Go method-set rules. Selectors can be shadowed or become ambiguous, so choose meaningful types and names.

Follow this diagram before executing the example. Check where a value or decision changes what runs next.

This example is a complete program. Save it as main.go or paste it into the Go Playground.

Go code

package main

import "fmt"

type Identity struct{ Name string }
type Employee struct {
	Identity
	Role string
}

func main() {
	employee := Employee{Identity: Identity{Name: "Sam"}, Role: "Engineer"}
	fmt.Println("Promoted:", employee.Name)
	fmt.Println("Explicit:", employee.Identity.Name)
	fmt.Println("Role:", employee.Role)
}

Output

Promoted: Sam
Explicit: Sam
Role: Engineer

Employee embeds Identity, making its Name field accessible both with employee.Name and employee.Identity.Name. The Role field remains a direct Employee field.

• An embedded struct is not a superclass; Go does not provide class inheritance.
• Promotion can be ambiguous when embedded types offer conflicting field or method names.

Embed a Details struct with an ID in an Order struct, then print the promoted ID.

Tip: Edit the example above, predict the output, and run the modified code to test your reasoning.

You have practiced Struct Embedding in a small, self-contained program. The important habit is to predict what runs, inspect the actual output and distinguish the language rule from the particular example.

Before continuing, make sure you can explain the program to someone who has not seen it, including the line that changes its result.