angular - Injecting into existing constructor -

i'm having difficulties trying inject service in angular. i'm trying create service extending class existing constructor, follows:

@injectable() export class authhttpservice extends authhttp {     constructor(options: authconfig, http: http, defopts?: requestoptions) {         super(options, http, defopts);     } } 

my issue is: need inject service , can't seem put argument in constructor (can't put required argument after optional 1 , if put optional ? doesn't work).

i've tried injector.get , works reasonably injects different instance of service other components , breaking app (i rely on service properties show information).

any solution? thanks!

to inject service, add constructor before optional parameter. fine.

@injectable() export class authhttpservice extends authhttp {     constructor(options: authconfig, http: http,                  otherservice: otherservice,                 defopts?: requestoptions) {         super(options, http, defopts);     } }