How to use Sphinx's autodoc to document a class's __init__(self) method?

Question

Sphinx doesn\'t generate docs for __init__(self) by default. I have tried the following:

.. automodule:: mymodule
    :members:

and

Answer 1

Over the past years I've written several variants of autodoc-skip-member callbacks for various unrelated Python projects because I wanted methods like __init__(), __enter__() and __exit__() to show up in my API documentation (after all, these "special methods" are part of the API and what better place to document them than inside the special method's docstring).

Recently I took the best implementation and made it part of one of my Python projects (here's the documentation). The implementation basically comes down to this:

import types

def setup(app):
    """Enable Sphinx customizations."""
    enable_special_methods(app)


def enable_special_methods(app):
    """
    Enable documenting "special methods" using the autodoc_ extension.

    :param app: The Sphinx application object.

    This function connects the :func:`special_methods_callback()` function to
    ``autodoc-skip-member`` events.

    .. _autodoc: http://www.sphinx-doc.org/en/stable/ext/autodoc.html
    """
    app.connect('autodoc-skip-member', special_methods_callback)


def special_methods_callback(app, what, name, obj, skip, options):
    """
    Enable documenting "special methods" using the autodoc_ extension.

    Refer to :func:`enable_special_methods()` to enable the use of this
    function (you probably don't want to call
    :func:`special_methods_callback()` directly).

    This function implements a callback for ``autodoc-skip-member`` events to
    include documented "special methods" (method names with two leading and two
    trailing underscores) in your documentation. The result is similar to the
    use of the ``special-members`` flag with one big difference: Special
    methods are included but other types of members are ignored. This means
    that attributes like ``__weakref__`` will always be ignored (this was my
    main annoyance with the ``special-members`` flag).

    The parameters expected by this function are those defined for Sphinx event
    callback functions (i.e. I'm not going to document them here :-).
    """
    if getattr(obj, '__doc__', None) and isinstance(obj, (types.FunctionType, types.MethodType)):
        return False
    else:
        return skip

Yes, there's more documentation than logic :-). The advantage of defining an autodoc-skip-member callback like this over the use of the special-members option (for me) is that the special-members option also enables documentation of properties like __weakref__ (available on all new-style classes, AFAIK) which I consider noise and not useful at all. The callback approach avoids this (because it only works on functions/methods and ignores other attributes).