Tag Interfaces

March 11, 2019 1 min read

When it comes to interfaces, a good practice is to create an interface where you’ll use it. Creating interfaces in advanced is not recommended in Go. There are two exceptions:

you’re creating a library which will be used in different projects
you’ll have more than 1 implementation

In the example below, we have a storage implementation.

type inMemoryStorage struct {
   mutex *sync.Mutex
   storage map[string]*Value
}

func NewStorage() *inMemoryStorage {
   return &inMemoryStorage{
      storage: map[string]*Value{},
      mutex: &sync.Mutex{},
   }
}

func (s inMemoryStorage) Set(ctx context.Context, value *Value) error  {
   s.mutex.Lock()
   s.storage[value.key] = value
   s.mutex.Unlock()
   return nil
}

func (s inMemoryStorage) Get(ctx context.Context, key string)  (*Value, error)  {
   if val, ok := s.storage[key]; ok {
      return val, nil
   }

   return nil, nil
}

func (s inMemoryStorage) GetAll(ctx context.Context)  map[string]*Value  {
   return s.storage
}

func (s inMemoryStorage) Remove(ctx context.Context, key string) error  {
   s.mutex.Lock()
   delete(s.storage, key)
   s.mutex.Unlock()
   return nil
}

As you can see, we skipped the interface(s) because they are not needed here.