github.com/logrange/linker (go): Package linker provides Dependency Injection and Inversion of Control functionality. The core component is Injector, which allows to register Components. Component is an object, which can have any type, which requires some initialization, or can be used for initializing other components. Every component is registered in the Injector by the component name or anonymously (empty name). Same object can be registered by different names. This could be useful if the object implements different interfaces that can be used by different components.  The package contains several interfaces: PostConstructor, Initializer and Shutdowner, which could be implemented by components with a purpose to be called by Injector on different initialization/de-initialization phases.  Init() function of Injector allows to initialize registered components. The initialization process supposes that components with 'pointer to struct' type or interfaces, which contains a 'pointer to struct' will be initialized. The initialization supposes to inject (assign) the struct fields values using other registered components. Injector matches them by name or by type. Injector uses fail-fast strategy so any error is considered like misconfiguraion and a panic happens.  When all components are initialized, the components, which implement PostConstructor interface will be notified via PostConsturct() function call. The order of PostConstruct() calls is not defined.  After the construction phase, injector builds dependencies graph with a purpose to detect dependency loops and to establish components initialization order. If a dependency loop is found, Injector will panic. Components, which implement Initializer interface, will be notified in specific order by Init(ctx) function call. Less dependant components will be initialized before the components that have dependency on the first ones.  Injector is supposed to be called from one go-routine and doesn't support calls from multiple go-routines.  Initialization process could take significant time, so context is provided. If the context is cancelled or closed it will be detected either by appropriate component or by the Injector what will cause of de-intializing already initialized components using Shutdown() function call (if provided) in reverse of the initialization order. Panic will happen then.
Keywords: dependency-injection|injector|ioc-framework|lifecycle