The last concept that we need to know when using Wire is provider sets. Provider sets offer a way to group providers, and this can be helpful when writing injectors. Their use is optional; for example, earlier we used a provider set called wireSet, as shown in the following code:

func initializeServer() (*rest.Server, error) {
   wire.Build(wireSet)
   return nil, nil
}

However, we could have passed in all the providers individually, as shown in the following code:

func initializeServer() (*rest.Server, error) {
   wire.Build(
      // *config.Config
      config.Load,

      // *exchange.Converter
      wire.Bind(new(exchange.Config), &config.Config{}),
      exchange.NewConverter,

      // *get.Getter
      wire.Bind(new(get.Config), &config.Config{}),
      get.NewGetter,

      // *list.Lister
      wire.Bind(new(list.Config), &config.Config{}),
      list.NewLister,

      // *register.Registerer
      wire.Bind(new(register.Config), &config.Config{}),
      wire.Bind(new(register.Exchanger), &exchange.Converter{}),
      register.NewRegisterer,

      // *rest.Server
      wire.Bind(new(rest.Config), &config.Config{}),
      wire.Bind(new(rest.GetModel), &get.Getter{}),
      wire.Bind(new(rest.ListModel), &list.Lister{}),
      wire.Bind(new(rest.RegisterModel), &register.Registerer{}),
      rest.New,
   )

   return nil, nil
}

Sadly, the previous example is not contrived. It's taken from our small example service.

As you might expect, there are plenty more features in Wire, but at this point we have covered enough to get us started.