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And why exactly do you trust a called method to determine whether or not you should be able to keep running? Like… do your job, you object. I didn’t load your l

by zoky 3y ago

And why exactly do you trust a called method to determine whether or not you should be able to keep running? Like… do your job, you object. I didn’t load your library and call a method on you to tell me what the state of my system is, I just want you to either do what I asked you to do or fail gracefully, and then I can decide whether we crash or not. > If a piece of the road is suddenly missing, the car needs to stop. Uh, no. If a piece of the road is missing, it’s up to the driver to stop, not the car. The car has no business whatsoever determining whether the road exists or not, except inasmuch as it communicates to the driver “hey, whatever the heck this is is difficult or impossible to drive on, your call what we do though.”

zozbot234 3y ago
> I just want you to either do what I asked you to do or fail gracefully, and then I can decide whether we crash or not. Then you're looking for resumable conditions, which just so happen to be effectively isomorphic to async-await. (The called function is effectively a piece of async code which 'awaits' upon a failure condition, after which it can either be resumed or canceled as with an ordinary panic.)
usrbinbash 3y ago
> just want you to either do what I asked you to do or fail gracefully And most of the time, this is EXACTLY what happens. In fact most libraries that do use panics, recover them internally and return errors to the callers. Again: panics are not errors, panics are not exceptions. A library should never panic in a way that it's caller notices, UNLESS it met a condition that simply is not recoverable, not by the library itself, and not by it's caller. Yes, this requires care by the libraries authors not to overuse panics. Yes, there are libraries that do overuse them. No, this doesn't change anything about what I wrote. If a library I use would do that, I would either fix the library, or find a better one. > Uh, no. If a piece of the road is missing Okay, let me try again with a better analogy: If a cars engine breaks down, the car will stop. It doesn't matter if the driver wants the car to go for another 100 kilometers. It stops. Period. Not because anyone or anything "wants" the car to stop, but because its engine "package" met a condition, under which the further running of whatever context it is used in (in this case, the car), is no longer feasible and/or possible. That is exactly what panicking in a way that hits the runtime communicates: Oh noes, the engine just broke down, and now the machine can no longer run.
- zoky 3y ago
  I’m not sure how valuable these analogies actually are, but your example of the broken engine really seems to go towards my point. If the car breaks down, the driver still has several options: coast downhill, switch to a different car, pull a bicycle out of the trunk, or just get out and continue on foot. But the car enforcing the end of the trip by simply exploding and killing the driver isn’t really an acceptable response to engine failure. A library that unrecoverably crashes your program for any reason is defective by design, and a programming language that purposely allows a library to do so as a design choice is also defective by design in my opinion.
  - usrbinbash 3y ago
    > If the car breaks down, the driver still has several options: The one option he doesn't have though: Continue running the car as-is. And that's the point I am making. > and a programming language that purposely allows a library to do so as a design choice is also defective by design in my opinion. You are entitled to your opinion of course, but I'm not going to agree, and it seems a lot of people are completely fine with that design decision: https://madnight.github.io/githut/#/pull_requests/2023/3 https://madnight.github.io/githut/#/pull_requests/2023/3 Again, the library isn't "crashing the program". The library meets a condition under which it can no longer function, no matter what the caller does, and can no longer function in a way that makes running the entire program infeasible. That is the point of panicking and not recovering it within the library. And yes that is the libraries call to make. Yes, it needs to have a very good reason to make that call. Very few libraries panic in that way. And the ones that do, and are widely used, have very good reasons to. If libraries do so without a good reason, then people stop using them.
    - zoky 3y ago
      > The one option he doesn't have though: Continue running the car as-is. And that's the point I am making. Exactly! So raise an EngineFailure exception and let the driver decide how to proceed. But don’t kill the driver because you can’t figure out how anyone could possibly recover from what seems to you like the end of the world, when it might just be a speed bump as far as the driver is concerned. > You are entitled to your opinion of course, but I'm not going to agree, and it seems a lot of people are completely fine with that design decision: https://madnight.github.io/githut/#/pull_requests/2023/3 https://madnight.github.io/githut/#/pull_requests/2023/3 I mean, a lot of people are fine with programming in PHP, that doesn’t make it a good choice. > And yes that is the libraries call to make. No. Absolutely, 100%, beyond question not. The library can’t possibly know every conceivable circumstance in which it is called, and therefore it is a guarantee that there is some conceivable set of circumstances from which what appears to be a fatal error from the library’s perspective is nothing more than a blip, or even a complete non-issue, from the perspective of the caller. Panicking the calling program so it can’t possibly continue is an abuse of trust, and any library that does so shouldn’t be admitted to any repo, and any language that allows it to do so is broken by design and should be considered harmful.

by zoky 3y ago

zozbot234 3y ago

> I just want you to either do what I asked you to do or fail gracefully, and then I can decide whether we crash or not. Then you're looking for resumable conditions, which just so happen to be effectively isomorphic to async-await. (The called function is effectively a piece of async code which 'awaits' upon a failure condition, after which it can either be resumed or canceled as with an ordinary panic.)

usrbinbash 3y ago

> just want you to either do what I asked you to do or fail gracefully And most of the time, this is EXACTLY what happens. In fact most libraries that do use panics, recover them internally and return errors to the callers. Again: panics are not errors, panics are not exceptions. A library should never panic in a way that it's caller notices, UNLESS it met a condition that simply is not recoverable, not by the library itself, and not by it's caller. Yes, this requires care by the libraries authors not to overuse panics. Yes, there are libraries that do overuse them. No, this doesn't change anything about what I wrote. If a library I use would do that, I would either fix the library, or find a better one. > Uh, no. If a piece of the road is missing Okay, let me try again with a better analogy: If a cars engine breaks down, the car will stop. It doesn't matter if the driver wants the car to go for another 100 kilometers. It stops. Period. Not because anyone or anything "wants" the car to stop, but because its engine "package" met a condition, under which the further running of whatever context it is used in (in this case, the car), is no longer feasible and/or possible. That is exactly what panicking in a way that hits the runtime communicates: Oh noes, the engine just broke down, and now the machine can no longer run.

zoky 3y ago
I’m not sure how valuable these analogies actually are, but your example of the broken engine really seems to go towards my point. If the car breaks down, the driver still has several options: coast downhill, switch to a different car, pull a bicycle out of the trunk, or just get out and continue on foot. But the car enforcing the end of the trip by simply exploding and killing the driver isn’t really an acceptable response to engine failure. A library that unrecoverably crashes your program for any reason is defective by design, and a programming language that purposely allows a library to do so as a design choice is also defective by design in my opinion.
- usrbinbash 3y ago
  > If the car breaks down, the driver still has several options: The one option he doesn't have though: Continue running the car as-is. And that's the point I am making. > and a programming language that purposely allows a library to do so as a design choice is also defective by design in my opinion. You are entitled to your opinion of course, but I'm not going to agree, and it seems a lot of people are completely fine with that design decision: https://madnight.github.io/githut/#/pull_requests/2023/3 https://madnight.github.io/githut/#/pull_requests/2023/3 Again, the library isn't "crashing the program". The library meets a condition under which it can no longer function, no matter what the caller does, and can no longer function in a way that makes running the entire program infeasible. That is the point of panicking and not recovering it within the library. And yes that is the libraries call to make. Yes, it needs to have a very good reason to make that call. Very few libraries panic in that way. And the ones that do, and are widely used, have very good reasons to. If libraries do so without a good reason, then people stop using them.
  - zoky 3y ago
    > The one option he doesn't have though: Continue running the car as-is. And that's the point I am making. Exactly! So raise an EngineFailure exception and let the driver decide how to proceed. But don’t kill the driver because you can’t figure out how anyone could possibly recover from what seems to you like the end of the world, when it might just be a speed bump as far as the driver is concerned. > You are entitled to your opinion of course, but I'm not going to agree, and it seems a lot of people are completely fine with that design decision: https://madnight.github.io/githut/#/pull_requests/2023/3 https://madnight.github.io/githut/#/pull_requests/2023/3 I mean, a lot of people are fine with programming in PHP, that doesn’t make it a good choice. > And yes that is the libraries call to make. No. Absolutely, 100%, beyond question not. The library can’t possibly know every conceivable circumstance in which it is called, and therefore it is a guarantee that there is some conceivable set of circumstances from which what appears to be a fatal error from the library’s perspective is nothing more than a blip, or even a complete non-issue, from the perspective of the caller. Panicking the calling program so it can’t possibly continue is an abuse of trust, and any library that does so shouldn’t be admitted to any repo, and any language that allows it to do so is broken by design and should be considered harmful.