How to Gracefully Handle Specific Errors in Go's Standard Library?

How to Accurately Handle Specific Errors

When working with Go's standard library functions, you may encounter situations where you only care about specific types of errors. For instance, if using rpc.Dial, you might only be interested in handling errors related to connection loss or refusal.

Using errors.Is and errors.As

The preferred way to catch specific errors in modern Go is with the errors.Is and errors.As functions:

if errors.Is(err, syscall.ECONNREFUSED) {
    // Connection refused error
} else {
    // Some other kind of error
}

These functions perform a deep comparison of the error with the given target error or error type.

When Specific Error Types Are Available

Some libraries use specific error types, making error handling simpler. For example, the net package defines several error types, including net.Error for network errors:

if _, ok := err.(net.Error); ok {
    if err.Error() == "connection lost" { ... }
}

Obtaining All Possible Errors

Determining all possible errors returned by a standard library function is not straightforward. The best approach is to review the source code or consult the godoc documentation for the function.

Cautionary Notes

• String comparison should be used sparingly, as it's fragile and can lead to incorrect error handling.
• The specific errors returned by a function may change in future Go versions.

The above is the detailed content of How to Gracefully Handle Specific Errors in Go's Standard Library?. For more information, please follow other related articles on the PHP Chinese website!