5 ms·

Because multiple return values for handling errors is a strictly inferior and error prone way for dealing with the matter.

• californical 6y ago
  It's interesting that you say this, because I've had the opposite experience. I wouldn't say it's strictly inferior, because there are definitely upsides. If it was strictly inferior, why would a modern language be designed that way -- there must be some debate right? I love multiple returns/errors. I find that I never mistakenly forget to handle an error when the program won't compile because I forgot about the second return value. I don't use go at work though, I use a language with lots of throw'ing exceptions, and I regularly miss handling exceptions that are hidden in dependencies. This isn't the end of the world in our case, but I prefer to be more explicit.
  • apta 6y ago
    > If it was strictly inferior, why would a modern language be designed that way golang is not a modern language (how old it is is irrelevent), and the people who designed it did not have a proper language design background (their other accomplishments are a different matter). Having worked on larger golang code bases, and I've seen several times where errors are either ignored or overwritten accidentally. It's just bad language design.
    • fooster 6y ago
      Error handling is hard, period. Error handling in go is no worse than any other language, and in most ways it is better being explicit and non-magic. > people who designed it did not have a proper language design background Irrelevant. > It's just bad language design. try { ... } catch(Exception ex) { ... }
      • apta 6y ago
        > try { ... } catch(Exception ex) { ... } The error here is explicitly handled, and cannot be accidentally ignored. Unlike golang where it's quite easy for errors to go ignored accidentally.
        • hactually 6y ago
          because it has try/catch. Without that (which would be similar to not checking the err in go) it explodes or throws to a layer up that may not expect it. Each language has its wonks.
          • apta 6y ago
            > Without that (which would be similar to not checking the err in go) it explodes or throws to a layer up that may not expect it. It's not similar to that at all. Without it, the exception bubbles up until it gets caught somewhere, or crashes the program with a useful stacktrace. With golang, it just goes undetected, and the code keeps running with corrupt state, without anyone knowing any better.
        • fooster 6y ago
          Nevertheless, this is how it is mostly done in Java. I haven't used eclipse in eons, but last time I did it even generated this code. If you care with go, use errcheck.
          • apta 6y ago
            Does errcheck work well with gorm (https://gorm.io/ https://gorm.io/) and it's way of returning errors? This is not an obscure library, it's quite widely used.
            • ori_b 6y ago
              Does any language save you from explicitly screwing up error handling? Gorm is doing the Go equivalent of: class Query { class QueryResult { Exception error; Value result; } public QueryResult query() { try { return doThing(); } catch(Exception e){ return new QueryResult(error, null); } } } Gorm is going out of its way to make error handling suck.
      • entha_saava 6y ago
        Exceptions don't lead to silent but dangerous and hard to debug errors. The program fails if exception is not handled.
    • dgb23 6y ago
      I cannot think of a language where errors cannot be ignored. In go it is easy to ignore them, but they stick out and can be marked by static analysis. The problems you describe are not solved at the language level, but by giving programmers enough time and incentives to write durable code.
      • apta 6y ago
        The following line in golang ignores the error: fmt.Println("foo") Compare to a language with exception handling where an exception will get thrown and bubbles up the stack until it either hits a handler, or crashes the program with a stack trace. And I was referring to accidental ignoring. I've seen variations of the following several times now: res, err := foo("foo") if err != nil { ... } if res != nil { ... } res, err = foo("bar") if res != nil { ... }
        • Mawr 6y ago
          Usage of linters fixes this: >The following line in golang ignores the error: fmt.Println("foo") fmt.Println() is blacklisted for obvious reasons, but this: a := func() error { return nil } a() results in: go-lint: Error return value of 'a' is not checked (errcheck) >And I was referring to accidental ignoring. I've seen variations of the following several times now: res, err := foo("foo") if err != nil { ... } if res != nil { ... } res, err = foo("bar") if res != nil { ... } results in: go-lint: ineffectual assignment to 'err' (ineffassign)
          • apta 6y ago
            > fmt.Println() is blacklisted for obvious reasons That's the issue with the language, there are so many special cases for convenience sake, not for correctness sake. It's obvious why it's excluded, but it doesn't make it correct. Do you want critical software written in such a language? Furthermore, does that linter work with something like gorm (https://gorm.io/ https://gorm.io/) and its way of handling errors? It's extremely easy to mis-handle errors with it. It's even a widely used library.
        • deleted 6y ago
• lenish 6y ago
  func foo() (*SomeType, error) { ... return someErr } ... result, err := foo() if err != nil { // handle err } // handle result vs type Result struct { Err error Data SomeType } func (r *Result) HasError() bool { return r.Err != nil } func bar() *Result { ... return &Result { ... } } ... result := bar() if result.HasError() { // handle result.Err } // handle result I'm not really sure I see the benefit to the latter. In a language with special operators and built-in types it may be easier (e.g. foo()?.bar()?.commit()), but without these language features I don't see how the Result<T> approach is better.
  • et1337 6y ago
    Go can't really express the Result<T> approach. In Go, it's up to you to remember to check result.HasError(), just like it's up to you to check if err != nil. If you forget that check, you'll try to access the Data and get a nil pointer exception. The Result<T> approach prevents you from accessing Data if you haven't handled the error, and it does so with a compile-time error. Even with Go's draconian unused variable rules, I and my colleagues have been burned more than once by forgotten error checks.
    • jatone 6y ago
      there are linters that will help you with that. https://github.com/kisielk/errcheck https://github.com/kisielk/errcheck https://golangci-lint.run/usage/linters/ https://golangci-lint.run/usage/linters/ has a solid set of options.
      • nimish 6y ago
        I just wish the linter was integrated into the compiler. And that code that didn't check would simply not compile
  • apta 6y ago
    The alternative is not the Result type you defined, but something along the lines of what languages like Rust or Haskell define: https://doc.rust-lang.org/std/result/ https://doc.rust-lang.org/std/result/
• dgb23 6y ago
  I would say it is a very ergonomic way of doing this. It allows for writing in a more exploratory way until you know what your error handling story is. Then, even if you choose to propagate it later, you just add it to your signature. Also it is very easy to grok and clear. Definitely not strictly inferior.