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				.. _sphinx-gotchas:

				Sphinx gotchas
				==============

				Here is a list of common gotchas when formatting Python docstrings for [http://www.sphinx-doc.org/en/stable/ Sphinx] and the [http://www.sphinx-doc.org/en/stable/ext/napoleon.html Napoleon] style.

				Sphinx
				------

				Lists
				+++++

				All sorts of `lists <http://www.sphinx-doc.org/en/stable/rest.html#lists-and-quote-like-blocks>`_
				require an empty line before the first bullet and after the last one,
				to be properly interpreted as list.
				No indentation is required for list elements w.r.t. surrounding text,
				and line continuations should be indented like the first character
				after the bullet

				Bad::

				this is a bad example that will not be interpreted as a list
				preceding text
				- foo
				- bar
				- baz
				following text

				Good::

				this is some text preceding the list

				- foo
				- bar
				- baz
				- this is a rather long-ish paragraph inserted in the list
				with line continuation
				- qux

				this is some text following the list

				Bad::

				- foo
				- nested lists also requires empty lines, but they are missing here
				- inner list 1
				- inner list 2
				- outer list continues here

				Good::

				surrounding text

				- foo
				- nested lists also requires empty lines

				- inner list 1
				- inner list 2

				- outer list continues here

				surrounding text

				Verbatim source code
				++++++++++++++++++++

				Verbatim `code blocks <http://www.sphinx-doc.org/en/stable/rest.html#source-code>`_,
				e.g., for code examples, requires double colon at the end of a line,
				then an empty line, and then the code block itself, indented:

				Bad::

				This does not work as there is a single column and no empty line before code:
				def foo(bar, baz):
				qux = bar + baz

				return qux

				Good::
				<pre>
				a nice example of python code follows::

				def foo(bar, baz):
				qux = bar + baz

				return qux

				here we can restart text flow

				Inline code samples use double backquotes, and not single ones.

				Bad::

				you have to instantiate the method `def foo(bar): pass`
				in order to use this abstract class

				Good:

				you have to instantiate the method ``def foo(bar): pass``
				in order to use this abstract class

				=== ``kwargs``, ``args`` ===

				`Asterisks needs to be escaped <http://www.sphinx-doc.org/en/stable/rest.html#inline-markup>`_
				to avoid capture by emphasis markup.
				In case of multiple adjacent asterisks, escaping the first one is enough.

				Bad::

				additional **kwargs are copied in the returned dictionary

				Good:

				additional \**kwargs are copied in the returned dictionary

				Code cross-references
				+++++++++++++++++++++

				Backquotes are not enough to cross-reference a Python entity
				(class, function, module, etc.); you need to use
				`Sphinx domains <http://www.sphinx-doc.org/en/stable/domains.html>`_ for that,
				and in particular the `Python domain <http://www.sphinx-doc.org/en/stable/domains.html#the-python-domain>`_

				Bad::

				see the `do_something` function and the `swh.useless` module
				for more information

				Good::

				see the :func:`do_something` function and the :mod:`swh.useless` module
				for more information

				Good::

				you can avoid a long, fully-qualified anchor setting an
				:func:`explicit label <swh.long.namespace.function>` for a link

				See also: the `list of Python roles <http://www.sphinx-doc.org/en/stable/domains.html#cross-referencing-python-objects>`_
				that you can use to cross-reference Python objects.
				Note that you can (and should) omit the <code>:py:</code> prefix,
				as Python is the default domain.

				Note also that when building Sphinx documentation
				for individual Software Heritage modules in isolation,
				cross-references to other modules will not be resolvable.
				But they will be resolvable when building the unified documentation
				from ``swh-docs``

				Napoleon
				--------

				Docstring sections
				++++++++++++++++++

				See the `list of docstring sections <http://www.sphinx-doc.org/en/stable/ext/napoleon.html#docstring-sections>`_
				supported by Napoleon.
				Everything else will not be typeset with a dedicated heading,
				you will have to do so explicitly using reStructuredText markup.

				Args
				++++

				Entries in Args section do not start with bullets, but just with argument names (as any other Napoleon section).
				Continuation lines should be indented.

				Bad::

				Args:
				- foo (int): first argument
				- bar: second argument
				- baz (bool): third argument

				Good::

				Args:
				foo (int): first argument
				bar: second argument, which happen to have a fairly
				long description of what it does
				baz (bool): third argument

				Returns
				+++++++

				In Returns section you need to use ":" carefully as, if present, it will be interpreted as a separator between return type and description. Also, the description of return value should not start on the same line of "Returns:", but on the subsequent one, indented.

				Bad::

				Returns:
				this does not work (colon will be interpreted as type/desc separator), a dict with keys:

				- foo
				- bar

				Good::

				Returns:
				this works (there is no colon) a dict with keys

				- foo
				- bar

				Good::

				Returns:
				dict: this works again (first colon identifies the type) a dict with keys:

				- foo
				- bar

				Bad::

				Returns: this is not good either, you need to start a paragraph

				Raises
				++++++

				You need a ":" separator between exception names and their description.

				Bad::

				Raises:
				ValueError if you botched it
				RuntimeError if we botched it


				Good::

				Raises:
				ValueError: if you botched it
				RuntimeError: if we botched it

				See also
				--------

				* :ref:`python-style-guide`