[_vvhw]

Loris Cro did a great talk on error handling in Zig, which also deals with how to return information with an error if you need to, and why the common case optimizes for simpler error values: https://www.youtube.com/watch?v=TOIYyTacInM

[dilap]

Thanks, that was a nice talk.

But the answer there is basically, "if you care about payload, don't use zig's built-in error handling." Which, obviously, you can do, but I'm not convinced it's a great answer!

Even for something as simple as parseInt, it would be nice, I would argue, if it returned, along with InvalidCharacter, which character was invalid. This would enable e.g. very precise indications in messages to the end user of what was wrong with the input.

In general, because currently it's super-ergonomic to return just error codes but more of a pain to return errors w/ payloads, what you'll get in practice is no error payload even when it would be useful, which will end up turning into less-helpful-than-ideal errors for end users, which is contrary to zig's goal of enabling the creation of perfect software. :-)

I found this thread interesting

https://github.com/ziglang/zig/issues/2647

[_vvhw]

Thanks for the link to that proposal.

Just thinking out loud, given Zig's errors primarily allow the compiler to enforce that errors are handled, and exhaustively, beyond that why can't error payloads just be passed as an input argument pointer to the function call? Maybe this is a dumb idea, but it's what C programs already do, except C programs don't have the safety of compiler checked errors offered by Zig. Does the Zig compiler need to check error payloads beyond the type system already provided? I'm not sure.

I agree with you that having such a super-ergonomic error handling system will direct most code towards a certain style, but I don't think this is contrary to Zig's goals of perfect software or simplicity. It's already such a huge win on top of C's error handling.

[dilap]

> Just thinking out loud, given Zig's errors primarily allow the compiler to enforce that errors are handled, and exhaustively, beyond that why can't error payloads just be passed as an input argument pointer to the function call?

Yeah, that's definitely a reasonable way to do it, and actually Andrew gives an example of this:

https://github.com/ziglang/zig/issues/2647#issuecomment-5898...

(Andrew's example is slightly different in that rather than an explicit argument, it's an optional field in one of the arguments.)

So it's definitely not like crazy bad or anything, but also definitely less ergonomic than if you could directly return a payload with the error, and this is enough friction that it feels like you'll end up not having error information when you want it (both as an API consumer and eventually as an end-user looking at an error message).

But, I'm still very new to Zig, so perhaps my instincts on that are wrong. :-)

[_vvhw]

> But, I'm still very new to Zig, so perhaps my instincts on that are wrong. :-)

Maybe you're right too! Just speaking for myself here, but as a programmer and "man with a hammer", I sometimes like to think that instincts might just be our mental machine learning model, where it can be really well trained and give the right black box answer, albeit not with the explanatory backstory or rationale, but worth trusting nevertheless.

I'm also new to Zig, and there are ways that a pointer input arg as error payload could go wrong. I'm following the proposal issue, and it will be interesting to see which way it goes.

[dilap]

I think you're spot on with your description of instincts. Which of course means sometimes they can lead us wrong, especially if we're applying them to domains very different from those they were trained on.