Jessica Temporal

Using Go to format Go code

calendar_today timer Reading time ~2 minutes

Code formatters are a beautiful thing to see, especially when you’re feeling lazy about formatting things or when you’re worried about learning a new language’s syntax and haven’t gotten the hang of the code style yet.

Today’s tip shows how the Go programming language helps you format code without suffering.

To start, we need to understand that well-formatted code has been part of Go’s culture since it was created. For the more experienced, this is just a very common best practice. But how does this work in practice? Alright, let’s say you wrote the following code in a file called helloworld.go:

package main
import "fmt"
func main(){
fmt.Println("Hello world!")
}

So far so good, this code compiles and if you do go run helloworld.go it still prints your Hello World! to the screen. However, if you had to send this code to an open source project, people reviewing your code would probably ask you to format it better.

There are a bunch of language-native tools to help the developer, one of them being gofmt. It can show the suggested formatting for a source code on the screen or even format the code you write for you. To use gofmt just pass the filename to it:

gofmt helloworld.go

That will print the formatted version of your source code to the screen. There are some flags you can use to change that result. For example, the -d flag will show a diff of your file in a format identical to git diff, great for sending patches.

But the most interesting flag/option is -w which converts the screen output to writing in the file. In that case, if you use that flag like so:

gofmt -w helloworld.go

Nothing will be printed to the screen and the formatted code will be written to your source file. So that code I showed at the beginning, after running with the -w flag, looks like this:

package main
 
import "fmt"
 
func main() {
        fmt.Println("Hello World!")
}

Cool right? Now you have no more excuse not to format your pretty little code 😜

Acknowledgments

Thanks especially to Cesar who has patiently been teaching me Go.

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