How Do I Access Embedded Fields in Go Structs?

Accessing Struct Type Embedded Fields

In Go, struct types can contain embedded fields, which allow for embedding one or more types within a struct. This powerful feature enables code reuse and efficient memory management. However, understanding how to access these fields can be challenging while learning about pointers.

Consider the following struct definitions:

<code class="go">type Engine struct {
    power int
}

type Tires struct {
    number int
}

type Cars struct {
    *Engine // Embedded field with pointer
    Tires   // Embedded field without pointer
}</code>

As you've observed, within the Cars struct, an embedded type pointer *Engine is defined. This allows access to the Engine type's methods and fields via the Cars struct.

To access the power field of the Engine embedded field, you must first initialize both the Engine and Cars structs. In the main function:

<code class="go">func main() {
    car := new(Cars) // Initialize Cars struct
    car.Engine = new(Engine) // Initialize Engine struct explicitly
    car.power = 342 // Set power field
    car.number = 4 // Set number field
}</code>

By explicitly initializing both structs, you establish a connection between the embedded *Engine pointer and the actual Engine object. Now, you can access the power field through the Cars struct:

<code class="go">fmt.Println(car.power) // Prints 342</code>

Similarly, for the non-pointer embedded field Tires, you can directly access its number field:

<code class="go">fmt.Println(car.number) // Prints 4</code>

This example demonstrates how to properly initialize and access embedded fields within a struct, enabling you to fully utilize code reuse and efficient memory management.

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