HallsByra.Rx

You got to have them somewhere - your favorite extensions and helpers for RX. This is where I keep my little darlings.

For now, it's just these extensions to IObservable:

Extension	Description
Multicast	MultiCast with a factory that recreates/disposes its ISubject upon subscribe/unsubscribe..
PublishBehavior	Shorthand for Multicast with a BehaviorSubject factory.
PublishReplay	Shorthand for Multicast with a ReplaySubject factory.
SkipNull	You guessed it. It skips null values.
PairWithPrevious	Pairs each element with its predecessor.

and this little helper:

Name	Description
FileSystem.WhenFileChanges	Observes a file for changes

Multicast

This is basically just an ordinary Multicast but with a Subject factory instead of a fixed Subject. It means the the subscription to the source and the Subject are created each time the observer count is positive and disposed when there are no subscribers.

My typical use case goes like this:

var settings = 
    FileSystem.WhenFileChanges(@".\settings.json")
    .Select(File.ReadAllText)
    .PublishReplay(() => File.ReadAllText(@".\settings.json"));

The above code has the following properties:

• Returns settings from file when the first observer subscribes
• Returns cached settings to subsequence observers
• Disposes all resources when no one is observing
• Only hits the file once on each update, regardless of the number of observers

Maybe there are other more elegant way of achieving this, but I haven't found out...

SkipNull

This one's only for the tough.

PairWithPrevious

Combines each element with its predecessor. Cold and simple.