~/Go Design Patterns Guide for Advanced Users

Sep 14, 2021

Go design patterns provide modular, reusable, and maintainable software architecture. Pattern selection depends on problem constraints.

Creational Patterns

Singleton ensures a class has only one instance. Use sync.Once to guarantee thread safety.

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package singleton
import sync

var once sync.Once
var instance *MyStruct

type MyStruct struct{}

func GetInstance() *MyStruct {
    once.Do(func() {
        instance = &MyStruct{}
    })
    return instance
}

Factory Method defers instantiation to subclasses, isolating object creation.

Builder constructs complex objects step by step. Useful for immutable structures or complex initialization.

Structural Patterns

Adapter allows incompatible interfaces to work together. It wraps an existing type with a compatible interface.

Decorator adds new behavior to objects, leveraging Go interfaces.

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type Notifier interface {
    Send(string) error
}

type EmailNotifier struct{}

func (e *EmailNotifier) Send(message string) error {
    // send email
    return nil
}

type SMSDecorator struct {
    Notifier Notifier
}

func (s *SMSDecorator) Send(message string) error {
    s.Notifier.Send(message)
    // send SMS
    return nil
}

Facade simplifies complex systems with a unified interface.

Proxy controls access and adds extra functionality, such as lazy loading.

Behavioral Patterns

Observer notifies multiple subscribers of state changes.

Strategy defines interchangeable algorithms within a family of algorithms.

Command encapsulates operations as commands, supporting undo and redo.

Best Practices

Prefer Go idioms, such as interfaces for polymorphism. Avoid unnecessary inheritance and favor composition, as Go does not support class-based inheritance. Use dependency injection for testability and modularity. Patterns should not be forced, use them only when they clarify intent and make codebase maintainable.

Additional Resources

• Effective Go
• Go Patterns
• Go Proverbs
• Design Patterns in Go
• Go Wiki: Patterns
• Refactoring Guru Go Patterns
• SourceMaking Design Patterns
• Tour of Go
• Go Forums
• Go Modules

This guide outlines advanced Go design patterns and usage for robust software systems.