An Rx question: I"ve just migrated to Rx 2 and on...

# random

[chris-hatton]

An Rx question: I"ve just migrated to Rx 2 and only just realised I can no longer have null elements in streams. In cases where null is notionally valid; such as a stream to fetch some cached user data, where there may be none... is it advisable to model these as exceptions NoUserDataException?

[wasyl]

chris-hatton: imo you should rather wrap your result in a class which will tell you whether you have data or not, as in

class CachedData {
  List<Data> data; // might be null
}

[chris-hatton]

Thanks, I will mull it over.

[chris-hatton]

Just wrapping it like you say does seem to be a fair solution

[chris-hatton]

Bit of a questionable removal at first meeting; but I'm sure they had their reasons...

[wasyl]

I usually use sealed classes for similar things

[chris-hatton]

Yes, sealed classes ftw

[chris-hatton]

So useful in many situations

[wasyl]

Actually why do you want to emit null when there’s no data yet?

[chris-hatton]

Heh, good question; it's a cop-out answer but also the truth to say I inherited this project

[chris-hatton]

and they've implemented some... 'Rx lite'

[wasyl]

Oh okay

[chris-hatton]

where Rx has sometimes been used as a convenience to swap between sync and async datasources easily

[chris-hatton]

and some sources emit Observable.just(null)

[chris-hatton]

when unset

[wasyl]

Rx in wrong hands is reaaaaly difficult to work with

[chris-hatton]

its not really in the philosophy but I have to work with what I've got

[chris-hatton]

done as much refactoring as I dare before the business are going to start demanding the next feature

[chris-hatton]

its one of those

[wasyl]

Yeah, makes sense