Interface for non-mutating functions on Observable

[ArdorDeosis]

edit: turns out I did mix some stuff up when I was reading the docs and this is obsolete since the observable class does not expose the mutating features.

I'd like to make a case for an interface (or interfaces) that contain non-mutating functions on an Observable that are meant to be used by a consumer. My concrete case is for the .pipe() method.

I found this (closed) PR about a similar topic, which was missing a (imo crutial) use case: encapsulation

Example Case
I have a ServiceImplementation implementing a ServiceInterface. The implementation is using an Observable internally. I want other services (consumers) to be able to subscribe to it, but they should not be able to call .next() (or .complete() or .error()) on it. They should only be able to observe, not change the state or fire events. This can be achieved by only exposing a Subscribable in ServiceInterface, but then consumers cannot use the .pipe() operator (which is defined on Observable). If I however expose the whole Observable, all consumers could call .next(), which should only happen from within my ServiceImplemntation.

For the moment I can create my own type or interface by copying the pipe signatures from the source, but this is not really maintainable, it will break whenever there are signature changes in RxJS. I think an interface containing .pipe() (and other non-mutating methods) would help here.

[ArdorDeosis]

To keep encapsulation, the return type of .pipe() on said consumer-interface should also not expose the whole Observable, but only the consumer-initerface.

[ArdorDeosis]

Yeah, so turns out I was just too stupid to read the documentation correctly and mixed some things up... So this can be closed, sorry for that.