How Can I Efficiently Handle Multiple Errors in Go?

Handling Multiple Errors in Go

Error handling in Go emphasizes explicit checking of errors where they occur. However, this can lead to verbose code when handling multiple errors in a single block.

Consider this contrived example:

package main

import (
    "fmt"
    "io"
    "io/ioutil"
    "os/exec"
)

func main() {
    cmd := exec.Command("cat", "-")
    stdin, err := cmd.StdinPipe()
    if err != nil {
        return
    }
    stdout, err := cmd.StdoutPipe()
    if err != nil {
        return
    }
    err = cmd.Start()
    if err != nil {
        return
    }
    _, err = io.WriteString(stdin, "Hello world!")
    if err != nil {
        return
    }
    err = stdin.Close()
    if err != nil {
        return
    }
    output, err := ioutil.ReadAll(stdout)
    if err != nil {
        return
    }
    fmt.Println(string(output))
    return
}

Each line handling errors adds three additional lines of code. Many of these errors are not fatal or handled elsewhere, leading to a perceived increase in boilerplate.

Idiomatic Error Handling

One idiomatic approach is to return errors from functions and handle them explicitly in the calling code.

package main

import (
    "fmt"
    "os"

    "errors"
)

func piping(input string) (string, error) {
    cmd := exec.Command("cat", "-")
    stdin, err := cmd.StdinPipe()
    if err != nil {
        return "", err
    }
    stdout, err := cmd.StdoutPipe()
    if err != nil {
        return "", err
    }
    if err = cmd.Start(); err != nil {
        return "", err
    }
    if _, err = io.WriteString(stdin, input); err != nil {
        return "", err
    }
    if err = stdin.Close(); err != nil {
        return "", err
    }
    all, err := ioutil.ReadAll(stdout)
    if err != nil {
        return "", err
    }
    return string(all), nil
}

func main() {
    in := "Hello world!"
    fmt.Println(in)
    out, err := piping(in)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    fmt.Println(out)
}

In this example, piping() returns both the output and any error encountered. The calling code can then handle the error or propagate it if necessary.

Error Handling in Go

In Go, explicit error handling is essential. The explicit if err != nil checks encourage programmers to handle errors immediately, avoiding unhandled errors that could lead to unexpected program behavior.

While this approach can lead to verbose code in some cases, it promotes a disciplined approach to error handling and maintainability.

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