Proposal: A built-in Go error check function, try

Your list there is almost a primer of "what not to do in Go", and is certainly not representative of the Go code in e.g. the standard library.

I sense some frustration about the language... what happened to make you so anti-Go?

I'd think anyone who creates a language is bound to be opinionated about what should be in a language, no?

In disguise? I do not believe there is any mystery that panic/recover provide exceptions in Go. An exceptional case is exactly when you would want to use panic in a Go program. panic is provided in the language specifically to deal with exceptions.

If anything, it is other programming languages where exceptions are usuals in disguise.

Fair point - this is a nasty result of their simple interface, and I think a mistake given much of the std lib doesn't use concrete types behind the interface. fmt.Errorf leads directly to this. It's simple, but not very flexible and can lead to horrible habits like parsing strings.

if .... else boilerplate

It's more like if boilerplate. People don't tend to use else unless absolutely necessary - it's if err deal with it, otherwise proceed. I agree errors in Go are more verbose than in some other languages, though in practice I don't find this a huge problem. I think I'd prefer result types but you're still handling it in a similar way.

Underscore everywhere to silence them Abuse from panic, aka exceptions in disguise

This is not how Go is used in practice, I mean I'm sure somebody somewhere does this but it is not the norm. I maintain large codebases at work with zero instances of these faults.

You do not need to parse error results in strings. Many libraries expose structural error types which can be inspected with type switches or other language mechanisms. However, for the most part, you can just treat all errors from a function the same.

There's definitely cases where you can't, like you may want to detect whether or not your error should be retried or treated as a permanent failure. You do the same thing you'd do with an exception: type-switch on the type of error, just like you'd catch on the type of exception. You can also do value comparisons for some errors that are constant, like io.EOF, which is handy in simple cases. The standard library also has some helpers for a couple common cases, like os.IsNotExist for checking if a file error occurred because the file did not exist.

The only time where you really, genuinely would need to parse strings is if you caught panics from the language runtime, which are actually just strings. However, this is unsupported, and the current Go HEAD actually just changed the format of an index out of bounds panic, so it would be very unwise to do this.

Examples of libraries that provide richer errors that satisfy the standard error interface:

- go-pg: https://godoc.org/github.com/go-pg/pg#Error

- elastigo: https://godoc.org/github.com/mattbaird/elastigo/lib#ESError

- redigo: https://godoc.org/github.com/gomodule/redigo/redis#Error (it's a string because the underlying protocol uses error strings.)

- gin: https://godoc.org/github.com/gin-gonic/gin#Error

The first three I picked because I used them, but the last one was fun. I just found one of the top Go libraries on GitHub explore and checked to see if they had a rich error type in their library, and they did. It's definitely common practice.

So yeah, you shouldn't be parsing error strings.

>- if .... else boilerplate

Yes that's the repetition problem that there's proposals to fix, but if that's the worst problem I still find it less annoying than needing this, which requires at least two new scopes:

    try {
        doThing(param[0]);
    } catch(e IOException) {
        Log.Warning(e.message);
        return;
    } catch(e ApiException) {
        throw new InvalidParameterException(String.Format("Invalid parameter: {}", param[0]), e);
    }

    //  Compiles
    //  No lint warning
    //  Sometimes correct!
    doThing(param[0]);

Without inspecting every possible codepath, it is impossible to know which errors are inadvertently not handled, and sometimes it is difficult to tell how a given error will be handled.

The correct thing to do in Go is almost always some variation of this, which is pretty simple:

    err := doThing(param[0])
    if err != nil {
        return err
    }

    err := doThing(param[0])
    if err == io.EOF {
        log.Printf("While doing thing: %v", err)
        return err
    } else if err != nil {
        return errors.Wrap(err, fmt.Sprintf("invalid parameter: %v", param[0]))
    }

>- Underscore everywhere to silence them

You shouldn't silence them, unless maybe if you are writing example code. But a lot of examples on the web will just have correct error handling, which seems like a win/win to me.

>- Abuse from panic, aka exceptions in disguise

That's just bad code. You even said 'abuse' yourself.

You can call them exceptions in disguise, but they're really not. This thinking basically implies all error handling that unwinds the stack is “exceptions.” If they were exceptions, presumably you'd love Go error handling, because it has exceptions. Panic is a lot more limited, and generally good software will only catch panics in a couple types of circumstances:

- At API boundary edges when dealing with an API that nests deeply. In this case, you can recover but panic if the error was not an API error. This would allow a library to avoid passing the error value around when the only logical thing to do with the error value is to pass it back to the library user; A good example would be a parser.

- When trying to isolate a failure, for example to prevent one HTTP request from taking down an entire HTTP server.

>If you want error handling without exception's guesswork, there are checked exceptions (used for the first time in CLU 1975), and result types (used for the first in ML in 1973)

Does your language of choice actually support checked exceptions? C#, Python, JavaScript don't. Only modern language I am aware of that does off-hand is Java, and I don't think very much at all uses it, because it is even more annoying than Go error handling.

>Just because they have a very good career, it doesn't make them always right.

No, but it would be awfully strange if they learned nothing from that experience, which is kind of what you implied.

>I tend to think for myself and not from opinions of others.

This is just an empty platitude.

I never claimed that my opinion of Go being good was due to the background of Rob Pike or Bell Labers in general, just pointing out that the point of 'I programmed in the 80s and 90s' seems kind of odd given the background of the language designers.

Go is very opinionated, but I happen to like those opinions, genuinely.

Then you should advise Google on what they are doing wrong.

"The State of Kernel Self Protection Project by Kees Cook, Google"

https://www.youtube.com/watch?v=aMkCKeZ8xZw