annotation

func NextAnonimousAnnotatation ¶

func NextAnonimousAnnotatation() inject.Annotation

/ NextAnonimousAnnotatation generates an unique annotation, / / This is used to override annotations to avoid duplication of providers. / For example, some module extends the another provider of another module, performing useful actions, / but keeping the provider signature. It is also necessary to allow to create several instances of this module / in the one injector. Here we use an anonymous annotation to override the annotation of the extensible provider. / / Example: / type server struct {} / type serverModule struct {} / func (_ serverModule) ProvideEndpoint() (string, server) { / return "server.com", server{} / } / / type readyServer struct {} / type waitModule struct {} / func (_ waitModule) ProvideValue(endpoint string, _ server) (string, readyServer, error) { / return endpoint, readyServer{}, waitEndpoint(endpoint) / } / func ModuleWithReadyServer(annotation inject.Annotation) inject.Module { / privateServerAnnotation := hackannotation.NextAnonimousAnnotatation() / return inject.CombineModules( / rewrite.RewriteAnnotations(serverModule{}, map[inject.Annotation]inject.Annotation{ / server{}: privateServerAnnotation, / }), / rewrite.RewriteAnnotations(waitModule{}, map[inject.Annotation]inject.Annotation{ / server{}: privateServerAnnotation, / readyServer{}: annotation, / }), / } / / type server1 struct {} / type server2 struct {} / injector, err := inject.InjectorOf( / ModuleWithReadyServer(server1{}), / ModuleWithReadyServer(server2{}), / ) / endpoint1 := injector.MustGet(new(string), server1{}).(string) / endpoint2 := injector.MustGet(new(string), server2{}).(string)