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Comment by djs070 | Hacker News Reader

Nicely done.

Is returning error common in go (as opposed to raising)?

Thanks! Go doesn't have exceptions and it is idiomatic[1] to return the error type. Dave Cheney has a really great blog post[2] which he describes why go does away with exceptions. The Golang wiki on GitHub has a great section[3] on errors as well.

1. https://gobyexample.com/errors

2. http://dave.cheney.net/2012/01/18/why-go-gets-exceptions-rig...

3. https://github.com/golang/go/wiki/Errors

> Go doesn't have exceptions

Go has panics, which are pretty much the same thing as exceptions in other languages (the details of how they are used are slightly different from, say, Java/Python/Ruby exceptions, but much more than, say, Perl 6 exceptions.)

Go has a strong stylistic recommendation not to expose panics to external consumers of code, and it is idiomatic to instead use error returns from publicly-exposed library code. But "Go doesn't have exceptions" is mostly misleading.

Rob Pike, one of the three creators of Golang, disagrees with you. In his blog post less is exponentially more[1] he shares a list of significant simplifications in Go over C and C++ which includes:

> no exceptions

1. http://commandcenter.blogspot.pt/2012/06/less-is-exponential...

And yet "panics" exist, with very similar semantics to exceptions in C++/Java/Python/Ruby.

Sure, there's differences between Go panics and any one of those implementations of exceptions (just as there are between them, or between any of them and Perl 6 exceptions.) But panics are clearly a variation on the exception theme, just as each of those forms of exceptions is.

The strong idiom of not having panics exposed across public interfaces of libraries is a cultural change, which to the extent that it is followed does present a simplification compared to ecosystems where you have to deal with both returns and exceptions in library code. But panics very much are exceptions, and changing the name doesn't change that.

As I was originally answering a question regarding whether it was normal to return errors or raise exceptions, and because I've read Dave Cheney and Rob Pike's blog posts explicitly stating Go does not have exceptions I replied as such.

However, after doing some research I learned that in addition to Panic() there's also Recover()[1], so I'll concede that there is similarity between panic/recover and throw/catch. Prior to my learning about Recover() I was under the assumption that Panic was just used to print a message and close a program with a non-zero status.

1. https://github.com/golang/go/wiki/PanicAndRecover

> "Go doesn't have exceptions" is mostly misleading.

It's worded too strongly perhaps. While `panic` behavior is similar to `java.lang.Exception`, it is not idiomatic to panic on problems like IOException/SQLException. They are detected by return codes to be handled immediately, rather than a broad swath of code wrapped in `try`.

This in Java:

    try
        code
        code
        code
    catch errA
        handle
    catch errB
        handle
    catch errC
        handle

Would be this in Go:

    code
       handle errA
    code
       handle errB
    code
       handle errC

It's fair to say "Go doesn't use exceptions" since Go doesn't use panics for common error handling.

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