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Comment by nine_k | Hacker News Reader

For exceptional, unforeseen situations you do have exceptions, aka "panic".

For signaling error conditions that the caller has to expect and handle, you have the `result, err = func(...)` idiom, and a compiler that would warn you if you forget to use the value of `err`.

If Rob Pike's opinion on this is not enough, here's Martin Fowler saying essentially the same thing: https://martinfowler.com/articles/replaceThrowWithNotificati...

In general: http://wiki.c2.com/?DontUseExceptionsForFlowControl

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Go does not warn you if you forget to handle an error. It only does so if the function in question also returned a value that you're using. There exist important functions that don't return non-error values and report errors that you very much would like to avoid dropping on the floor: os.Chdir() for example.

While this is technically true, I've considered `errcheck` to be standard tooling for what feels like forever now, and it does exactly this; make sure you're checking your errors.

I’ve read the first article. It was eye opening, cause I am writing a bot right now and using exceptions to control input flow. Made me think about my design.

That said, it does not argue against exceptions. So, I am not sure what your argument is.

Exceptions are bad outside the "your computer just started burning" cases, but Go has replaced them with something even worse, "multiple return values".

So instead of some imagined return of "int or throw Exception" you now have "(int, error)", which basically means that the result of a function call can be any of these four options:

  - (   value, no error)
  - (no value,    error)
  - (   value,    error)
  - (no value, no error)

And due to the lack of Generics you can't abstract over your error handling.

And due to the lack of proper ADTs you can't even properly model "value OR error" manually.

Feels like Javascript callback error handling. Which was not much fun.

Just without the callbacks. At least you could abstract over error handling with callbacks...

The last two options are not idiomatic Go. (zero, err) and (nonZero, nil) are. So the error check is almost always a simple `if err != nil {return err}`.

> The last two options are not idiomatic Go.

Who are the authors of https://golang.org/pkg/io again?

Yeah, 90% of Go devs agree with you.

10% think it is a really great idea.

So you can never be sure without reading the documentation.

The last case is rarely seen in Go (at least not in the standard library).

Accepting for the moment that Go has no exceptions and and error returns are the way to go, the first two cases make sense.

The third case ( value, error) is actually useful in several scenarios. For instance, considering you're writing bytes to a stream that fail partway. The value is the number of bytes return so far and the error is the error that was encountered. In fact, this is the signature that the ubiquitous io.Writer's Write method uses.

If all you had was single return values (aka "int or throw Exception"), how would you model the io.Writer?

> If all you had was single return values (aka "int or throw Exception"), how would you model the io.Writer?

This is not an problem, because a single return value is _not_ everything one has.

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