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Author is still early in their exploration and has some definite mistakes in here. Probably the biggest one is around the error handling, thinking that the only
by jerf 9mo ago
Author is still early in their exploration and has some definite mistakes in here. Probably the biggest one is around the error handling, thinking that the only way to interact with an error is through the error interface itself. That is intended as a baseline interaction, a fallback for when nothing else is appropriate, such as just slamming an error into a log. If you want to interact with specific errors, you should use the various functions in the errors package [1] to check for specific types, and then use those specific types in whatever they support. Go error support is quite good; you can return an error object that says "The user was not found, the file the user was supposed to be found in was not found, and while trying to log this the log failed to accept the write" as various error types composed together, and any consumer of the error using the errors package can pick out the various bits of the error they understand using those tools without having to understand the error binding them together or the components it doesn't care about . You should never use string manipulation to check errors unless you have no choice, and whatever library left you with no choice should have an issue filed against it. It doesn't come up often, but it does sometimes come up; most recently I had the AWS SDK emitting an error I could only use string functions on, but I think they've since fixed it.
I don't like the term "enums" because of the overloading between simple integers that indicate something (the older, more traditional meaning) and using them to mean "sum types" when we have the perfectly sensible term "sum type" already, that doesn't conflict with the older meaning. If you want sum types, a better approach is to combine the sort of code structure defined here: https://appliedgo.net/spotlight/sum-types-in-go/ https://appliedgo.net/spotlight/sum-types-in-go/ with a linter to enforce it https://github.com/alecthomas/go-check-sumtype https://github.com/alecthomas/go-check-sumtype , which is even better used as a component of golangci-lint: https://golangci-lint.run/ https://golangci-lint.run/
I'd also add my own warnings about reaching for sum types when they aren't necessary, in a language where they are not first class citizens: https://jerf.org/iri/post/2960/ https://jerf.org/iri/post/2960/ but at the same time I'd also underline that I do use them when appropriate in my Go code, so it's not a warning to never use them. It's more a warning that sum types are not somehow Platonically ideal. They're tools, subject to cost/benefit analysis just like anything else.
[1]: https://pkg.go.dev/errors https://pkg.go.dev/errors
- dkarl 9mo ago> I don't like the term "enums" because of the overloading between simple integers that indicate something (the older, more traditional meaning) I disagree with this. I'm old as hell, and I learned programming in a context where enums were always ints, but I remember being introduced to int enums as "we're going to use ints to represent the values of our enum," not "enums are when you use ints to represent a set of values." From the very beginning of my acquaintance with enums, long before I encountered a language that offered any other implementation of them, it was clear that enums were a concept independent of ints, and ints just happened to be an efficient way of representing them.
- 9rx 9mo ago"Enum" is literally defined as a numbering mechanism. While integers are the most natural type used to store numbers, you could represent those numbers as strings if you really wanted. The key takeaway is that a enum is a value, not a type. The type the link was struggling to speak of seems to be a tagged union. Often tagged union implementations use enums to generate the tag value, which seems to be the source of confusion. But even in tagged unions, the enum portion is not a type. It remains just an integer value (probably; using a string would be strange, but not impossible I guess).
- dkarl 9mo agoIt feels obvious that that's where the term originated, but I've never seen it used as a definition. In a mathematical context, something is enumerable if it can be put into 1:1 correspondence with the integers, but it doesn't need to be defined by a canonical correspondence. This suggests that being a finite (in a programming context where the set of ints is finite) set of discrete values is the defining feature, not the representation.
- 9rx 9mo ago> In most applications of int enums, the particular integers can be chosen at random I’m not sure the definition of "enum" enforces how things are identified. Random choice would be as good as any other, theoretically. In practice, as it relates to programming, random choice is harder to implement due to collision possibilities. Much simpler is to simply increment an integer, which is how every language I've ever used does it; even Rust, whose implementation is very similar to Go's implementation. But it remains that the key takeaway is that the enum is a value. The whole reason for using an enum is for the sake of runtime comparison. It wouldn't even make sense to be a type as it is often used. It is bizarre that it keeps getting called one.