How to Gracefully Handle Multiple Errors in Go?

Handling Multiple Errors Gracefully in Go

In Go, handling multiple errors in a clean and concise manner can be a challenge. Consider the following code snippet:

aJson, err1 := json.Marshal(a)
bJson, err2 := json.Marshal(b)
cJson, err3 := json.Marshal(c)
dJson, err4 := json.Marshal(d)
eJson, err5 := json.Marshal(e)
fJson, err6 := json.Marshal(f)
gJson, err4 := json.Marshal(g)

if err1 != nil {
    return err1
} else if err2 != nil {
    return err2
} else if err3 != nil {
    return err3
} else if err4 != nil {
    return err4
} else if err5 != nil {
    return err5
} else if err5 != nil {
    return err5
} else if err6 != nil {
    return err6
}

This code has several issues. First, it uses multiple if statements to handle each error separately. This makes the code verbose and difficult to read. Second, it returns the first error it encounters, which may not be the most important or relevant error.

There is a better way to handle multiple errors in Go using a function closure. Here is a revised version of the code using a function closure:

var err error
f := func(dest *D, src S) bool {
    *dest, err = json.Marshal(src)
    return err == nil
}

f(&aJson, a) &&
    f(&bJson, b) &&
    f(&cJson, c) &&
    f(&dJson, d) &&
    f(&eJson, e) &&
    f(&fJson, f) &&
    f(&gJson, g)

return err

This code defines a function closure (f) that takes two parameters: a pointer to a destination variable and a source value. The closure attempts to marshal the source value into the destination variable and sets an error if unsuccessful.

The function closure is then invoked for each source value, and the results are combined using the && operator. If any of the function closures return an error, the overall err variable will be set accordingly. Otherwise, the err variable will be nil.

This code is much cleaner and more concise than the original code. It also handles all of the errors in one go, making it easier to identify the most important error.

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