Pretty sure I broke switchIfEmpty :confused: ``` f...

# rx

[blakelee]

Pretty sure I broke switchIfEmpty 😕

fun doThings(): Maybe<Boolean> {
    Log.d("TEST", "HIT")
    return Maybe.just(true) 
}

return Maybe.just("")
    .map { false }
    .switchIfEmpty(doThings())

My log message still shows even though my Maybe is not empty

[kioba]

what you do here is

.switchIfEmpty({ 
    Log.d("TEST", "HIT")
    return Maybe.just(true) 
  }()
)

[kioba]

note that to be able to return Maybe.just(true) you have to execute the doThings() function which triggers the log all the time.

[kioba]

switchIfEmpty expects an observable as argument doThings() eagerly called when the return statements called

[blakelee]

Is there a way to defer it?

[kioba]

fix for the expected behaviour:

fun doThings(): Maybe<Boolean> =
Maybe.just(true)
    .doOnNext{ Log.d("TEST", "HIT") }

[blakelee]

Okay, that’s an interesting approach

[kioba]

doThings() will execute to generate a maybe. but the maybe will only be executed if switchIfEmpty triggers it which triggers the log

[blakelee]

I get what you’re saying. I guess I expected it to not even get to the switchIfEmpty until it was actually empty

[blakelee]

Thank you for your help!

[kioba]

add(1, 1.inc()) <-- here we expect that inc() will be executed before add. same is true for switchIfEmpty

func(...) \\ "..." is always eager unless it is wraps the code in lazy evaluation

[blakelee]

yup, that makes sense to me