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Comment by mukunda_johnson | Hacker News Reader

> It’s very similar to thread-local storage. We know how bad of an idea thread-local storage is. Non-flexible, complicates usage, composition, testing.

I kind of do wish we had goroutine local storage though :) Passing down the context of the request everywhere is ugly.

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I like explicit over implicit. I will take passing down context (in the sense of the concept, not the specific Go implementation) explicitly everywhere over implicit ("put it somewhere and I'll trust I can [probably, hopefully] get it back later") any day of the week.

I've seen plenty of issues in Java codebases where there was an assumption some item was in the Thread Local storage (e.g. to add some context to a log statement or metric) and it just wasn't there (mostly because code switched to a different thread, sometimes due to a "refactor" where stuff was renamed in one place but not in another).

Most recently ive been bit by this with datadog. The Python version does some monkeypatching to inject trace info. The go version you need to inject the trace info explicitly. While the latter takes more setup, it was much easier to understand what was going on and to debug when we ran into issues.

Sounds very familiar. I was a Java developer for a long time, and in that ecosystem adding a library to your project can be enough for code to be activated and run. There are plenty of libraries where the idea is: just include it, magic stuff will happen, and everything works! That is, until it doesn't work. And then you have to try and debug all this magic stuff of how Java automatically loads classes, how these classes are created and run, and what they do. Didn't happen very often, but when it happened usually a full week was wasted with this.

I really prefer spending a bit more time to set it up myself (and learn something about what I'm using in the process) and knowing how it works, than all the implicit magic.

This is why I avoid Python. I started doing Go after looking for few solutions written and Python and I couldn’t use it.

Some magic values inside objects of recursive depth changing dynamically at the runtime. After working for some time with functional languages and languages with non-mutable structures I’m afraid of such features today.

Context is nice because it’s explicit. Even function header spills the detail. `GetXFromName(context.Context, string)` already says that this call will do some IO/remote call and might never return or be subject of cancellation.

now your stuff breaks when you pass messages between channels

Goroutines have a tiny stack at the beginning, 4KB iirc. Having a goroutine-local storage will probably open a can of worms there.

Context's spread just like exceptions do, the moment you introduce one it flies up and down all the functions to get where it needs to be. I can't help but think that local storage and operations for Go just like Threads have in Java would be a cleaner solution to the problem.

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