Chapter 3. The gofmt formatting tool

Instead of a style guide, the Go programming language uses the gofmt code formatting tool. gofmt automatically formats your code according to the Go layout rules.

3.1. Prerequisites

3.2. Formatting code

You can use the gofmt formatting tool to format code in a given path. When the path leads to a single file, the changes apply only to the file. When the path leads to a directory, all .go files in the directory are processed.

Procedure

To format your code in a given path, run:

  • On Red Hat Enterprise Linux 8:

    $ gofmt -w <code_path>
    • Replace <code_path> with the path to the code you want to format.
  • On Red Hat Enterprise Linux 9:

    $ gofmt -w <code_path>
    • Replace <code_path> with the path to the code you want to format.
Note

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

3.3. Previewing changes to code

You can use the gofmt formatting tool to preview changes done by formatting code in a given path. The output in unified diff format is printed to standard output.

Procedure

To show differences in your code in a given path, run:

  • On Red Hat Enterprise Linux 8:

    $ gofmt -w -d <code_path>
    • Replace <code_path> with the path to the code you want to compare.
  • On Red Hat Enterprise Linux 9:

    $ gofmt -w -d <code_path>
    • Replace <code_path> with the path to the code you want to compare.

3.4. Simplifying code

You can use the gofmt formatting tool to simplify your code.

Procedure

  • To simplify anf format code in a given path, run:

    • On Red Hat Enterprise Linux 8:

      $ gofmt -s -w <code_path>
      • Replace <code_path> with the path to the code you want to simplify.
    • On Red Hat Enterprise Linux 9:

      $ gofmt -s -w <code_path>
      • Replace <code_path> with the path to the code you want to simplify.

3.5. Refactoring code

You can use the gofmt formatting tool to refactor your code by applying arbitrary substitutions.

Procedure

  • To refactor and format your code in a given path, run:

    • On Red Hat Enterprise Linux 8:

      $ gofmt -r -w <rewrite_rule> <code_path>
      • Replace <code_path> with the path to the code you want to refactor and <rewrite_rule> with the rule you want it to be rewritten by.
    • On Red Hat Enterprise Linux 9:

      $ gofmt -r -w <rewrite_rule> <code_path>
      • Replace <code_path> with the path to the code you want to refactor and <rewrite_rule> with the rule you want it to be rewritten by.

3.6. Additional resources