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This is down to developer style and agreements though; Go has typed errors and a set of utilities to match them [0]. Not using those is a choice, just like how in Java you can just `catch (Exception e)` after calling a dozen methods that might each throw a different exception.

[0] https://pkg.go.dev/errors

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Yoric a day ago | parent [-]

Interestingly, every time (and I mean _every_ time) that I've tried to use `errors.As` on errors raised by lib code, I found out that the lib just went with "nah, I'm just going to use `errors.New` or `fmt.Errorf`", which makes the error impossible to match.

So... I'd say that this is a fumble in the design of Go.

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wbl a day ago | parent [-]

%W exists to solve this

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Yoric 7 hours ago | parent | next [-]

It would, if people actually defined new errors. But, as I mentioned in my message, people just use `errors.New` or `fmt.Errorf`, all the way down, so you end up with errors that cannot be matched. Which means, in turn, that if these are errors that should be handled properly (and not just propagated/logged), they cannot.

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the_gipsy 21 hours ago | parent | prev [-]

How? Stringly matching? That's not typesafe at all.

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wbl 18 hours ago | parent [-]

No it wraps the underlying error

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the_gipsy 9 hours ago | parent [-]

But the underlying error stays unmatchable. Doesn't sound like a solution if you have to duplicate every error type, and worse, they don't even map 1:1 but now you have the same underlying error wrapped to god knows how many different errors.

For example, the lib produces some an error "bad file descriptor". You'll be wrapping it when you call fileOpen, fileDelete, etc etc 20 times. So you will be wrapping it in "open error", "delete error", etc, 20 times. You cannot try to match it to "bad file descriptor", that information is lost, you now have 20 relatively useless errors.

Except if you stringly match.

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wbl 5 hours ago | parent [-]

https://pkg.go.dev/errors#Is and https://pkg.go.dev/fmt#Errorf clearly state that there is a way to match these errors if the package exposes the values, which the stdlib does.

	▲	the_gipsy 40 minutes ago \| parent [-]
		Ah okay, it seems to work because errors are pointers, and errors.Is just checks for equality.