What canceled my Go context?

lemoncucumber 3 hours ago | parent | next [-]

It’s great that they identified this (incredibly common) pain point and introduced a way to solve it, but I can’t help being disappointed.

Reading the examples I found myself thinking, “that looks like a really useful pattern, I should bookmark this so I can adopt it whenever I write code like that.”

The fact that I’m considering bookmarking a blog post about complex boilerplate that I would want to use 100% of the times when it’s applicable is a huge red flag and is exactly why people complain about Go.

It feels like you’re constantly fighting the language: having to add error handling boilerplate everywhere and having to pass contexts everywhere (more boilerplate). This is the intersection of those two annoyances so it feels especially annoying (particularly given the nuances/footguns the author describes).

They say the point is that Go forces you to handle errors but 99% of the time that means just returning the error after possibly wrapping it. After a decade of writing Go I still don’t have a good rule of thumb for when I should wrap an error with more info or return it as-is.

I hope someday they make another attempt at a Go 2.0.

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lenkite an hour ago | parent | next [-]

I close my nose and always wrap errors with a sentinel error for public functions/methods so that callers can check with `errors.Is`. And you can always identify the place in the call-stack where the error occurred.

I need to start getting used to context with cancel cause - muscle memory hasn't changed yet.

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rednafi 2 hours ago | parent | prev | next [-]

Author here. I absolutely hated writing this piece after shooting myself in the foot a thousand times.

Go's context ergonomics is kinda terrible and currently there's no way around it.

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XorNot 3 hours ago | parent | prev [-]

There are two things I think you could have as implict in Go - error values, and contexts.

Just pass along two hidden variables for both in parameters and returns, and would anything really change that the compiler wouldn't be able to follow?

i.e. most functions return errors, so there should always be an implicit error return possible even if I don't use it. Let the compiler figure out if it needs to generate code for it.

And same story for contexts: why shouldn't a Go program be a giant context tree? If a branch genuinely doesn't ever use it, the compiler should be able to just knock the code out.

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maleldil an hour ago | parent [-]

What's the difference between an implicit error and exceptions? Being explicit about errors is good. Go's syntactical implementation, coupled with its unexpressive type system, is the problem.

	▲	XorNot 17 minutes ago \| parent [-]
		I will freely go on the record as saying that there's nothing wrong with exceptions for this exact reason: errors are so common that a function being "pure" is the exception, and that errors-as-value handling invariable turns into an endless chain of something like "if err; return (nil/zero, err)" in every language which tries it. The same would apply to anytime you have Result types - ultimately its still just syntactic sugar over "if err then...". What's far more common in real programs is that an error can occur somewhere where you do not have enough context to handle or resolve it, or you're unaware it can happen. In which case the concept of exceptions is much more valid: "if <bad thing here> what do I want to do?" usually only has a couple of places you care about the answer (i.e. "bad thing happened during business process, so start unwinding that process" and many more where the answer is either "crash" or "log it and move on to the next item".

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ashishb 5 hours ago | parent | prev [-]

Context cancellation (and it's propagation) is one of the best features in Go.

Is there any equivalent in major popular languages like Python, Java, or JS of this?

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ndriscoll 5 hours ago | parent | next [-]

ZIO in Scala tracks this sort of thing except you don't have to remember to pass around or select on the ctx (it's just part of the fibre/"goroutine"); if it's cancelled, the fibre and its children just stops the next time it yields (so e.g. if it "selects" on anything or does any kind of IO).

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deathanatos 4 hours ago | parent | prev | next [-]

Python async tasks can be cancelled. But, I don't think you can attach must context to the cancel (I think you can pass a text message), so it would seem the argument of what go suffered from would apply.

(I also think there's some wonkiness with and barriers to understanding Python's implementation that I don't think plagues Go to quite the same extent.)

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lifis 4 hours ago | parent | prev | next [-]

All mainstream languages have it in one or more forms (either direct task I/O cancellation, or cancellation tokens or I/O polling that can include synthetic events) since otherwise several I/O patterns are impossible

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perfmode 4 hours ago | parent | prev | next [-]

one of the reasons why i love writing control planes in Go.

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nnx 5 hours ago | parent | prev | next [-]

in JS, signals and AbortController can replicate some of the functionality but it's far less ergonomic than Go.

https://github.com/ggoodman/context provides nice helpers that brings the DX a bit closer to Go.

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drdaeman 5 hours ago | parent | prev | next [-]

C# has CancellationToken, but it’s just for canceling operations, not a general purpose context.

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richbell 4 hours ago | parent | prev | next [-]

Kotlin Coroutine's structured concurrency. Cancelling a parent automatically cancels child jobs, unless explicitly handled not to. https://kotlinlang.org/docs/coroutines-basics.html

	▲	tadfisher 3 hours ago \| parent [-]
		Stupidly, child cancellation cancels the parent scope as well, unless the scope opts out by including SupervisorJob.

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Quekid5 3 hours ago | parent | prev | next [-]

Java's Virtual Threads (JVM 21) + the Structured Concurrency primitives (not sure exactly what's available in Java 21+) do this natively.

Also, a sibling poster mentioned ZIO/Scala which does the Structured Concurrency thing out of the box.

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gzread 5 hours ago | parent | prev [-]

Not really, since they don't have `select`

There's a stop_token in some Microsoft C++ library but it's not nearly as convenient to interrupt a blocking operation with it.