DI feature: lifecycle hooks for services, especially OnDestroy #13618

I'm submitting a ... (check one with "x")

[ ] bug report 
[x] feature request
[ ] support request 

Current behavior

When destroying an injector, Angular has no way AFAIK to inform the service instances in the injector that they are doomed.

If a service is holding valuable resources (e.g., a message bus holding subscriptions) it doesn't know to let go.

Expected behavior

If the service has an ngOnDestroy, Angular should call it as it destroys/releases its hold on an injector (e.g., when destroying a component).

Is this safe? Only if the service is created by the injector ... which isn't always the case ( almost anything except useClass).

OTOH, if the developer adds an ngOnDestroy method, she should expect it to be called and not put her service in compromising position.

On balance, I think its a useful feature, with no obvious substitution, and one consistent with disposable patterns in other languages.

p.s.: The only other lc-hook that makes sense is ngOnInit and the developer can easily compensate for its lack. I can't think of workaround for the lack of ngOnDestroy.

All

• Angular version: 2.3.0

• Browser: [all ]

• Language: [all ]