Documentation and Type Hints

The pyglet documentation is written in reStructuredText (RST), and built with Sphinx. If you are not familiar with reStructuredText, it is similar to MarkDown but offers more robust functionality for creating technical documentation. This is the default language used in Sphinx. Most of the documentation is written in plain ascii text, so you can still modify or add to it without needing to know much RST syntax.

The documentation can be found as part of the pyglet repository, under the doc subfolder. The main index is located at pyglet/doc/index.rst, which includes the main landing page, and defines three toctrees:

  • The programming guide

  • The API docs

  • The development guide

programming guide

The programming guide is made up of many individual .rst files, which are located in the repository under the pyglet/doc/programming_guide/ folder. All files in this folder are also defined in the index.rst, in order to includes them in the build process.

API documentation

The API documentation is generated direclty from the source code docstrings by autodoc, a plugin extension that is included with Sphinx. The generation itself is mostly automatic, but declaration files are necessary to instruct Sphinx how and which modules and classes should be included. Look through the existing files at pyglet/doc/modules/ to get an idea of what this looks like.

docstring rules

  • Google Format with no typing.

  • Docstrings are meant primarily for user or general information, not implementation details.

  • Hash (#) comments should be used for developers or contributors when needing to provide information to other developers.

  • Any methods or functions without a docstring will not appear in the API documentation.

  • Documentation will hide private attributes unless otherwise overridden in the rst.

  • Parameter descriptions are not required if straight forward enough, unless a clarification is needed.

  • If you have to add a parameter description, you must add one for each in that function. (None or All)

  • A return description is optional.

  • All classes and functions should have a header with at least a one line succinct description.

  • For class attributes, use Attributes: in the header. Type hints may be specified, as currently they are not picked up automatically.
    • Required: You will also need to add these :exclude-members: <attribute> in the rst files manually. Otherwise, autodoc will pick it up twice.

    • Class attributes are generally meant to be used for:
      1. Changing global behavior to the class in some form. (Example: Texture.default_mag_filter)

      2. Simplifying subclassing for users. (Example: group_class for Sprite)

      3. Troubleshooting purposes.

  • Parameter descriptions should be indented on a new line for clarity.

  • Parameter descriptions can have one line of space between each for clarity.

  • For class instance attributes, these should be documented with a #: <description> comment.

  • For class instance attributes you wish to hide from the docs. Either:
    1. Consider making them private (via _name) if it makes sense.

    2. Mark them with a comment in this format: #: :meta private:

typing rules

  • Do not put type information in docstrings, rely on annotations.

  • If you are using class annotations, you must have from __future__ import annotations at the top of the module.

  • When adding annotations, if a class type is not used in the file, it must be imported only within TYPE_CHECKING

  • No need to go overboard, some rules can be set to ignored if there is not yet an adequate way to do it.

  • Return types always need to be specified even if None.


class Class1():
    """Short description of the class

    This is a good place for a general high level description
    of what the class is, and what it is used for. For example:
    Class1 is used for X and Y, which makes Z possible, etc.

    #: This is the default thing.
    some_default_thing: float = 123.0

    #: :meta private:
    dont_show_me: int = 456

    def __init__(self, name: str, size: float):
        """Constructor description

        Here is where you can describe how to make an instance of the
        class. If any of the arguments need further explaination, that
        detail can be added as necessary. For example:
        You must provide a name and a size, etc. etc.

            name: The name of this object.
            size: The size, in centimeters.
        """ = name
        self.size = size

        #: :This will show in the docs
        self.attribute_one: int = None

        self.attribute_two: str = "hello"

    def set_size(self, centimeters: float) -> None:
        """Simple description + type hints are enough."""
        self.size = centimeters

    def calculate_scaled_size(self, scale: float) -> float:
        """Detailed method description

        You can add more details here.

            scale: The argument description.

            Describe what is being returned, if not already clear.
        # This is a developer comment, which is not intended for end users to
        # see. These can be used to explain to future developers why something
        # is implemented a certain way, or any other developer focused notes, etc.
        return self.size * scale

def function_with_pep484_type_annotations(param1: int, param2: str) -> bool:
    """Example function with PEP 484 type annotations.

        param1: The first parameter.
        param2: The second parameter.

       When necessary, you can describe the return value in
       more detail. This can be skipped if it's obvious from
       the return type hint.

documentation tips

Sometimes you may, or may not want certain class attributes to show up in the API docs. Depending on how and where you put the annotations and/or comments, you can control what gets picked up during the documentation building. Some examples are shown below.

The following will show in docs WITHOUT docstring:

class Test:
    blah: int

The following will show in docs WITH docstring:

class Test:
    #: :My description.
    blah: int

The following will NOT show in the docs:

class Test:
    def __init__(self):
        self.blah: int = 0

The following will show in the docs:

class Test:
    def __init__(self):
        #: :This is documented.
        self.blah: int = 0

Developer reference

Developer focused documentation is located in the pyglet/doc/internal/ folder. This contains various pages about tools that are used with developing pyglet, the documentation page that you’re reading now, information on unit tests, etc. These pages are useful for anyone who wants to contribute.


Building the documentation locally requires a few dependencies. See Development environment for more information on how to install them. Once you have Sphinx and it’s dependencies installed, you can proceed with the build. The first way to build is by using pyglet’s included utility. This is found in the root of the repository, and includes some helper functions for common build and distribution related tasks. For docs, execute:

./ docs --open

If the build succeeds, the generated static web pages will be in doc/_build/html.

You can also build the documentation by using Sphinx’s Makefile:

cd pyglet/doc
make html       # Posix
make.bat html   # Windows

auto-generated details


2024/06/10 07:45:14

pyglet version