How Can I Include Line Numbers in Go's log.Fatal Error Messages?

Getting Error Line Numbers in Go Logs

When using log.Fatal to handle errors in Go, it's crucial to also gather the line number where the error was thrown. This can aid in debugging and readability.

Using Flags

One method to retrieve the line number is by setting the Flags on the custom Logger or the default Logger. Both Llongfile and Lshortfile options are available:

• Llongfile includes the full path to the file and line number.
• Lshortfile shows only the line number.

Setting Flags for Default Logger

To modify the default Logger, use the following code:

log.SetFlags(log.LstdFlags | log.Lshortfile)

This will add the line number to all logs emitted by the default Logger.

Customizing Flags

To create a custom Logger with specific flags, use the following syntax:

logger := log.New(os.Stdout, "my-app", log.LstdFlags | log.Lshortfile)

This custom logger, named "my-app," will now include the line number in its logs.

Usage

After setting the flags, simply use log.Fatal as usual. The printed error will include the line number, making it easier to trace the error's origin.

Advantages

Using flags is a standard and convenient way to add line numbers to logs. It eliminates the need for additional debugging tools or custom error handling code. Additionally, it allows you to easily switch between different logging levels, including Llongfile and Lshortfile, based on your preferences.

The above is the detailed content of How Can I Include Line Numbers in Go's log.Fatal Error Messages?. For more information, please follow other related articles on the PHP Chinese website!