Does Go Have Standard Error Variables Like Java, and What Are the Best Practices for Handling Errors?

Understanding Error Variables in Go

In Golang, it is common practice to declare error variables and utilize them within custom error structures. This approach enables the determination of the cause of an error. For instance, in strconv.go, ErrRange and ErrSyntax are declared and used within NumError structs to specify the type of error that occurred.

Are There Standard Error Variables?

While Java offers defined error types like IllegalArgumentException, Go does not provide a comprehensive set of standard error variables. Instead, there are several idiomatic methods for package authors to handle error returns:

1. Fixed Error Variables: Variables with fixed values and error names (e.g., ErrSomethingBad)
2. Error Types: Custom types with additional information (e.g., SomeError{ExtraInfo: 42})
3. Ad Hoc Errors: New errors created as needed using errors.New("error message")
4. Errors from Standard Packages: Using errors from standard packages like io.EOF (limited usage, usually accompanied by own errors)
5. Interface with Specific Error Behavior: Defining an interface like net.Error that provides error behaviors/types (e.g., Timeout(), Temporary())
6. Returning Existing Errors with Context (Go 1.13 ): Error wrapping using fmt.Errorf("context: %w", err) with the new %w formatting verb

When to Use Which Error Type

The first, second, and fifth methods are preferred if any consumer of your package may desire to test specific errors. These methods allow explicit comparisons or type assertions to determine the type of error that occurred.

The third method is suitable for errors that are unlikely to be tested, as they lack a consistent way to compare errors.

Use errors from the standard packages sparingly, opting for custom errors to provide a more granular response.

Additional Resources

For further insights into error handling in Golang, refer to the following resources:

• Effective Go on errors
• The Go Blog: Error handling and Go
• Dave Cheney: Inspecting Errors
• Peter Bourgon: Programming with errors

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