How to use $check in InterruptibleProcessor.php?

[wowcut]

Hi first let me thank you for this code, seems like this is exactly what I was looking for!
I just wanted to implement some kind of dependency for the individual stages of a pipeline with some extensive try catch error handling but then stumbled across the InterruptibleProcessor.php and I was wondering if there might be a better way to do that, but I am not sure how to use the $check callable - do I understand the code right that it allows for one $check callable for each pipeline and not for one $check for each $stage?

I just want to let pipelines stop or skip or trigger a different pipeline based on the results of one stage.

Also I am wondering: what would be the best way to build fallback chains? Something like "if stage_x fails, try again with $stage_y" or "if $stage_x produces result x skip to stage_z"?

I am just experimenting to learn if it might make sense to transform an existing large if-then-else monstrosity into a few pipelines and do not immediately see how to implement such kind of fallbacks. Also of course I would like to avoid writing lots of try catch error handling code - the result should be less code than the if-then-else horror I would like to replace... :)

If you could find the time for providing a little example how you would implement such a thing, it would be a great help! Thanks for your attention!

[AliasAPI]

// This is one way to check for errors and skip to the end of a pipeline during processing . . .

// Create the Pipeline
$pipeline = (new Pipeline(
// Set the processor to InterruptibleProcessor (instead of FingersCrossed)
new InterruptibleProcessor(
// Create a class GetOkay->__invoke() that calls $payload->getOkay()
// Pass GetOkay into InterruptibleProcessor so it knows where to check.
new GetOkay
)
))
// Create a Payload class with setOkay(), getOkay(), and a private property $okay
// Note: Line 25 InterruptibleProcessor is " if (true !== $check($payload)) { "
->pipe(new CreatePayload)
// Create a CheckBeforeFirstAction class to update $payload->setOkay() as needed.
// This class can check to make sure all requirements are OK to run FirstAction.
// Tip: Every class in the pipeline should (modify and) return the $payload object.
->pipe(new CheckBeforeFirstAction)
// CheckBeforeFirstAction(Payload $payload) returns the $payload object.
// The InterruptibleProcessor will check for an error using GetOkay->_invoke()
// If $payload->okay is still set to true the FirstAction will run
->pipe(new FirstAction)
// Create a CheckBeforeSecondAction class to $payload->setOkay() as needed.
->pipe(new CheckBeforeSecondAction)
// Set $payload->setOkay('false') inside CheckBeforeSecondAction as a test.
// The InterruptibleProcessor will check for an error using GetOkay->_invoke()
// The SecondAction will NOT be run since $payload->okay = false.
->pipe(new SecondAction);
// The $payload will be returned from InterruptibleProcessor.

// wowcut: Set a property in the $payload to specify which stages should run.
// I don't think you will reduce the if-then-else, but you can hide them in Check classes

Thanks to creator and maintainer of the Pipeline!

Drew