Chapter 3. gofmt

In Go Toolset, gofmt is provided by the go-toolset-7-golang package and is automatically installed with the go-toolset-7 package. See Section 1.4, “Installing Go Toolset”.

To format all code in the code_path path, run the gofmt tool as follows:

$ scl enable go-toolset-7 'gofmt -w code_path'

This command will directly change code in the code_path path. When code_path is a single file, the changes apply only to the file. When code_path is a directory, all .go files in the directory are processed.

When the code_path is omitted, gofmt reads standard input instead.

To print the formatted code to standard output instead of writing to the original file, omit the -w option.

It is possible to invoke gofmt through the go compiler with the fmt command. To achieve the same results as the command above, run:

$ scl enable go-toolset-7 'go fmt -l -w -s code_path'

To preview changes done by formatting code in a given path code_path, run the gofmt tool with the -d option as follows:

$ scl enable go-toolset-7 'gofmt -d code_path'

The output in unified diff format is printed to standard output.

It is possible to combine both the -d and -w options.

To simplify code in a given path code_path, run the gofmt tool with the -s option as follows:

$ scl enable go-toolset-7 'gofmt -s code_path'

The code under code_path is simplified. Use the -d option to show the differences, and use the -w option to apply the changes to the code.

The gofmt tool can be used to refactor code by applying arbitrary substitutions. To refactor code in a given path code_path according to a rule rewrite_rule, run the gofmt tool with the -r option as follows:

$ scl enable go-toolset-7 'gofmt -r rewrite_rule code_path'

The code under code_path is refactored according to the rule rewrite_rule. Use the -d option to show the differences, and use the -w option to apply the changes to the code. The additional options must be placed after the rule rewrite_rule:

$ scl enable go-toolset-7 'gofmt -r rewrite_rule -d code_path'

Detailed description of the rewrite rules is beyond the scope of this book. For more information, see the resources listed in Section 3.6, “Additional Resources”.

A detailed description of the gofmt tool and its features is beyond the scope of this book. For more information, see the resources listed below.

Online Documentation

See Also