2-phase (cycle?) scanning

[crankydillo]

I have a use-case where I need the result of one ScanningRecipe (i.e. its accumulator) in a following scanning recipe. I hacked this by having them sequential in a recipe list and using a static class variable. This is a one-off, one-time use recipe, so we feel OK with a few hacks; however, the general problem might be repeated. I'm curious if I missed a standard approach here.

I tried having them in order and putting a message in the ExecutionContext, but that failed with you-should-not-mutate-this message. Pretty sure I saw the backdoor to allow that, but for various reasons, I thought that was worse than using static class state.

I don't see how cycles gives any more state options..

Am I missing some pattern/strategy/etc that could be used for this? Anyone done this in a less hacky way than using static class variables?

[timtebeek]

hi! Indeed it's uncommon and somewhat advised against; could you make your use case more concrete? That might help us think through the options with you, as well as what accommodations might be in order. As it stands it's hard to say if you have a convincing case, with how generalized the description is at the moment.

[crankydillo]

I'll have to work on making it more concrete (been on vacation and wanted to drop a reply:). Ultimately, this roots back to the use case behind some rewrite-analysis questions (like this one) and how to conditionally chain recipes (I know you are supposed to use visitors:).

But.. it doesn't seem crazy that you might need 2 (or N) passes to ultimately build up an object that can be used in an LST-transforming visitor.

[timtebeek]

Thanks for the context and I hope you enjoyed your holiday! On the topic of data flow we added a completely new implementation:

• https://docs.moderne.io/openrewrite-advanced-program-analysis/data-flow

Perhaps that can help you there instead of the complications & limitations you're running into here.

[crankydillo]

Thanks Tim. I guess for now, let's close this. When/if we have a need for multi-cycle scanning, we'll come back. Our current solve is hacky (using static state), but this is not in a super-critical recipe.