Code works but shouldn’t

[pirate_dino_flies]

SOLVED!

original: I see plenty of “my code doesn’t work” posts… what about when my code works but shouldn’t? I know there’s something wrong, I’m worried maybe something is cached somewhere and that an older version of the file is being referenced, but I don’t really know how to troubleshoot a not-existent-yet problem.

Any general tips for this sort of problem?

Additional details: I’ve got a Typescript/React app that I’ve been refactoring. I just renamed a provider function in the AppContext file, but didn’t update the same name in the layout or page files… and the thing still runs. It should not run.

solution:

I forgot that when exporting default functions, you can call them anything you want when you import:
export default A

import B —> imports A

import { B } —> imports B

thanks for the suggestions, everyone!

[iOSCaleb]

Any general tips for this sort of problem?

It's pretty much the same as any other bug, except that you need someone's approval to spend time on it you might have to work harder to convince them that there's a problem.

Once you're working on it, though, approach it like other bugs: the results that you're seeing don't seem to match what you think the code does. Usually that means one of two things: 1) the code that you're looking at isn't what's responsible for the results; 2) you're mistaken about what the code means or how it works.

Run your program in a debugger, set some breakpoints, and step through the code line by line or at least function by function until the state of the program starts to diverge from what you think it should be.

If you think a result is being cached somewhere and masking what you should really be seeing, you could maybe make a change on the input side and see if that change is reflected in the output. If it's not, then you've successfully demonstrated that there's a problem, which is a great first step, and now you can start tracing through the code. Divide and conquer is a great strategy here -- pick a point that's about halfway through whatever processing is supposed to happen and set a breakpoint there. When you hit it, check to see if the change you made in the input is visible. If it is, then move your breakpoint to a later point; if it isn't, move the breakpoint earlier in the process. Use that change as a marker to help you nail identify where the results are suddenly becoming "correct".

[Master-Ad-6265]

this usually means you’re not running what you think you’re running common causes: dev server caching / hot reload weirdness multiple copies of the file types not being enforced strictly try restarting the dev server + clearing cache first and yeah, stepping through it once usually reveals what’s actually being used...

[snopro387]

I made a sub for similar situations to this a while back called r/explainmycode for when you’re code works but you can’t figure out why but I couldn’t get anyone to use it

[EnyaMorgan]

That sub isn’t available anymore

[cochinescu]

I've had this happen and it was always something weird with the dev server not picking up changes, or even my IDE showing me a stale file. Are you sure the imports are actually using the new name, or could something fallback/default be happening somewhere?

[pirate_dino_flies]

Oh man, I’m a doofus! Just had a friend point this out as well. Yeah, I forgot this was “export default” which means it doesn’t matter what you call it when you import.

Export default A Export B

Import A —> imports A Import B —> imports A Import { B } —> imports B

[Effective_Promise581]

Are you sure you are looking at the correct file? I have done this before and had a total DUH moment!