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# Translate Styleguide

The Translate styleguide is the styleguide for all Translate projects, including Translate Toolkit, Pootle, Virtaal and others. Patches are required to follow these guidelines.

## pre-commit hooks

The Translate styleguide can be checked by pre-commit. The Translate toolkit repository repository contains configuration for it to verify the committed files are sane. After installing it (it is already included in the `pyproject.toml`) turn it on by running `pre-commit install` in Translate toolkit checkout. This way all your changes will be automatically checked.

You can also trigger check manually, to check all files run:

    pre-commit run --all

## Python

The Python code follows PEP 8 and is linted and formatted using ruff. It is included the above-mentioned pre-commit hooks.

Any new code should utilize PEP 484 type hints. We’re not checking this in our CI yet as existing code does not yet include them.

## Documentation

We use Sphinx to generate our API and user documentation. Read the reStructuredText primer and Sphinx documentation as needed.

### Special roles

We introduce a number of special roles for documentation:

- `:issue:` – links to a toolkit issue Github.

  - `:issue:`234`` gives: issue 234

  - `:issue:`broken <234>`` gives: broken

- `:opt:` – mark command options and command values.

  - `:opt:`-P`` gives `-P`

  - `:opt:`--progress=dots`` gives `--progress=dots`

  - `:opt:`dots`` gives `dots`

- `:man:` – link to a Linux man page.

  - `:man:`msgfmt`` gives msgfmt

### Code and command line highlighting

All code examples and format snippets should be highlighted to make them easier to read. By default Sphinx uses Python highlighting of code snippets (but it doesn’t always work). You will want to change that in these situations:

- The examples are not Python e.g. talking about INI file parsing. In which case set the file level highlighting using:

      .. highlight:: ini

- There are multiple different code examples in the document, then use:

      .. code-block:: ruby

  before each code block.

- Python code highlighting isn’t working, then force Python highlighting using:

      .. code-block:: python

Note

Generally we prefer explicit markup as this makes it easier for those following you to know what you intended. So use `.. code-block:: python` even though in some cases this is not required.

With command line examples, to improve readability use:

    .. code-block:: console

Add `$` command prompt markers and `#` comments as required, as shown in this example:

    $ cd docs
    $ make html  # Build all Sphinx documentation
    $ make linkcheck  # Report broken links

## User documentation

This is documentation found in `docs/` and that is published on Read the Docs. The target is the end user so our primary objective is to make accessible, readable and beautiful documents for them.

## Docstrings

Docstring conventions:

  All docstrings are formatted with reStructuredText as understood by Sphinx. Depending on the number of lines in the docstring, they are laid out differently. If it’s just one line, the closing triple quote is on the same line as the opening, otherwise the text is on the same line as the opening quote and the triple quote that closes the string on its own line:

      def foo():
          """This is a simple docstring."""

      def bar():
          """This is a longer docstring with so much information in there
          that it spans three lines.  In this case the closing triple quote
          is on its own line.
          """

Please read PEP 257 (Docstring Conventions) for a general overview, the important parts though are:

- A docstring should have a brief one-line summary, ending with a period. Use `Do this`, `Return that` rather than `Does ...`, `Returns ...`.

- If there are more details there should be a blank line between the one-line summary and the rest of the text. Use paragraphs and formatting as needed.

- Use reST field lists to describe the input parameters and/or return types as the last part of the docstring.

- Use proper capitalisation and punctuation.

- Don’t restate things that would appear in parameter descriptions.

    def addunit(self, unit):
        """Append the given unit to the object's list of units.

        This method should always be used rather than trying to modify the
        list manually.

        :param Unit unit: Any object that inherits from :class:`Unit`.
        """
        self.units.append(unit)

Parameter documentation:

  Document parameters using reST field lists as follows:

      def foo(bar):
          """Simple docstring.

          :param SomeType bar: Something
          :return: Returns something
          :rtype: Return type
          """

Cross referencing code:

  When talking about other objects, methods, functions and variables it is good practice to cross-reference them with Sphinx’s Python cross-referencing.

Other directives:

  Use paragraph-level markup when needed.

Note

We still need to gather the useful ones that we want you to use and how to use them. E.g. how to talk about a parameter in the docstring. How to reference classes in the module. How to reference other modules, etc.

Module header:

  The module header consists of a utf-8 encoding declaration, copyright attribution, license block and a standard docstring:

      #
      ... LICENSE BLOCK...

      """A brief description"""

Deprecation:

  Document the deprecation and version when deprecating features:

      from translate.misc.deprecation import deprecated

      @deprecated("Use util.run_fast() instead.")
      def run_slow():
          """Run fast

          .. deprecated:: 1.5
             Use :func:`run_fast` instead.
          """
          run_fast()