Operators: Observables from functionals (Action0, Func0, Runnable, Calla...

[akarnokd]

...ble)

I've created 4 operators that turn ordinary action/function calls into Observables, but unlike start and Async, the functions are called on each subscription instead of only once. They can be thought of a more generalized from(T value). Each method is named according to the accepted type to avoid overload issues with Java 8 & various dynamic languages.

The 4 additional overloads lets the user specify the scheduler where the function is called. By default, the functions are called on the threadPoolForComputation.

I don't know if there are Rx.NET equivalents of these (or they ever existed).

[cloudbees-pull-request-builder]

RxJava-pull-requests #556 FAILURE
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[akarnokd]

9 threads were busy with something else...

[benjchristensen]

Right now I'd like to pass on adding these as it adds to the surface area of the API without strong reason. These are all wrapper methods of Observable.create which already takes a function and it is trivial to invoke an Action, Callable, Runnable etc from within the OnSubscribeFunc.

I'm not yet convinced that they are globally useful and worth increasing the already huge Observable signature, particular the from operator.

[akarnokd]

How about introducing ObservableEx like Rx.NET had once? This way, these tools don't get lost but are not part of core.

[benjchristensen]

Merge these into #696 instead.