p. exported from angular2/di_annotations defined in angular2/src/di/annotations.js (line 134) :markdown A marker annotation that marks a class as available to `Injector` for creation. Used by tooling for generating constructor stubs. ``` class NeedsService { constructor(svc:UsefulService) {} } @Injectable class UsefulService {} ``` .l-main-section h2 Members .l-sub-section h3 constructor pre.prettyprint code. constructor() :markdown