In the Go programming language, struct types and interfaces provide powerful ways to build readable and maintainable code. By using Go's structural composition and defining clear interfaces, we can create codebases that are easy to understand and modify. Let's explore these concepts in action.

Encapsulation in Go is achieved through package-level visibility and methods attached to structs. In Go, package-level visibility is achieved by starting the variable and method names with a lowercase letter, making them unexported and accessible only within the same package. Instead of classes, Go uses structs to group related fields and methods, making code more organized.

Consider student information scattered within a program:

Encapsulation is achieved by grouping these fields in a struct and creating methods to operate on them:

By encapsulating student properties and methods within a Student struct, we enhance the code's readability and maintainability.

Abstraction in Go is accomplished through interfaces, which define method signatures that any implementing type must fulfill.

Here's a simple function outside a struct to calculate a GPA:

We can integrate this calculation within the Student struct, exposing only necessary methods to the user:

The Student struct now abstracts the GPA calculation, simplifying interaction.

Polymorphism in Go is achieved using interfaces. By requiring structs to implement a common set of methods, we achieve dynamic behavior based on types.

Consider this scenario involving different shapes:

Here, both Rectangle and Triangle implement a Draw method, allowing for polymorphic behavior through the Shape interface.

In Go, struct embedding provides a straightforward way to achieve composition. This builds relationships between objects and allows for complex constructs from simpler pieces.

Consider a Window managing its content directly:

Refactor this with composition using struct embedding:

By separating concerns through composition, we improve code modularity and manageability.

In this lesson, we explored how to leverage Go's structs, interfaces, and embedding to create organized, maintainable, and flexible code. Through proper encapsulation, abstraction, polymorphism, and composition, we achieve scalable codebases aligned with Go idioms. Practice these principles to develop cleaner and more efficient Go programs. Happy coding!