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Thu, 1 Oct 2020 10:52:31 +0200 (CEST) From: Markus Armbruster To: John Snow Subject: Re: [PATCH v4 04/46] qapi: modify docstrings to be sphinx-compatible References: <20200930043150.1454766-1-jsnow@redhat.com> <20200930043150.1454766-5-jsnow@redhat.com> <87wo0bejmy.fsf@dusky.pond.sub.org> <96ba9e08-9806-baa3-62d2-2df84a666e62@redhat.com> Date: Thu, 01 Oct 2020 10:52:31 +0200 In-Reply-To: <96ba9e08-9806-baa3-62d2-2df84a666e62@redhat.com> (John Snow's message of "Wed, 30 Sep 2020 13:22:13 -0400") Message-ID: <87blhm49bk.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/01 04:25:37 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.469, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Thomas Huth , Eduardo Habkost , qemu-devel@nongnu.org, Cleber Rosa , Alex =?utf-8?Q?Benn=C3=A9e?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" John Snow writes: > On 9/30/20 4:47 AM, Markus Armbruster wrote: >> John Snow writes: >> >>> I did not say "sphinx beautiful", just "sphinx compatible". They will >>> not throw errors when parsed and interpreted as ReST. >> "Bang on the keyboard until Sphinx doesn't throw errors anymore" >> might >> be good enough for a certain kind of mathematician, but a constructive >> solution needs a bit more direction. Is there a specification to >> follow? Other useful resources? >> > > I don't know if you are asking this question rhetorically, or in good faith. I ask to make sure I understand goals and limitations of your doc string work in this series. Also, even a passing to Sphinx becomes more useful when accompanied by a link to relevant documentation. > Let me preface this by saying: This series, and these 119 patches, are > not about finding a style guide for our docstring utilization or about > proposing one. It is also not about rigorously adding such > documentation or about finding ways to meaningfully publish it with > e.g. Sphinx, or the styling of such pages. > > Why bother to add docstrings at all, then? Because I needed them for > my own sake when learning this code and I felt it would be a waste to > just delete them, and I am of sound mind and able body and believe > that some documentation was better than none. They are useful even > just as plaintext. > > Having said that, let's explore the actual style I tend to use. > > I mentioned before in response to a review comment that there isn't > really any standard for docstrings. There are a few competing > "styles", but none of which are able to be programmatically checked > and validated. > > The primary guide for docstrings is PEP 257, of which I follow some > but not all of the recommendations. > > https://www.python.org/dev/peps/pep-0257/ I find PEP 257 frustrating. It leaves me with more questions than answers. > In general, > > - Always use triple-double quotes (unenforced) > - Modules, classes, and functions should have docstrings (pylint) > - No empty lines before or after the docstring (unenforced) > - Multi-line docstrings should take the form (unenforced): > > """ > single-line summary of function. > > Additional prose if needed describing the function. > > :param x: Input such that blah blah. > :raises y: When input ``x`` is unsuitable because blah blah. > :returns: A value that blah blah. This paragraph is already not PEP 257. > """ > > PEP257 suggests a form where the single-line summary appears on the > same line as the opening triple quotes. I don't like this, and prefer > symmetry. PEP257 *also* suggests that writing it my way is equivalent > to their way, because any docstring processor should trim the first > line. I take this as tacit admission that my way is acceptable and has > merit. I prefer the symmetric form myself. > What about the syntax or markup inside the docstring itself? there is > *absolutely no standard*, but Sphinx autodoc recognizes a few field > lists as significant in its parsing, so I prefer using them: Doc link? > :param x: Denotes the parameter X. Do not use type information in the > string, we rely on mypy for that now. > > :raises y: explains a case in which an Exception type y may be raised > either directly by this code or anticipated to be allowed to be raised > by a helper call. (There's no standard here that I am aware of. I use > my judgment. Always document direct raise calls, but use your judgment > for sub-calls.) > > :returns: explains the semantics of the return value. > > That said, literally any sphinx/ReST markup is OK as long as it passes > make sphinxdocs. Some sphinx markup is prohibited, like adding new > full-throated sections. You can use arbitrary field lists, definition > lists, pre-formatted text, examples, code blocks, whatever. > > In general, you are not going to find the kind of semantic validation > you want to ensure that the parameter names are correct, or that you > spelled :param: right, or that you didn't miss a parameter or an > exception. None of that tooling exists for Python. > > Thus, it's all rather subjective. No right answers, no validation > tools. Just whatever seems reasonable to a human eye until such time > we actually decide to pursue publishing the API docs in the > development manual, if indeed we ever do so at all. > > That series sounds like a great opportunity to hash this all out. That > is when I would like to remove --missing-docstring, too. There will > absolutely be a "docstring series" in the future, but I am insisting > stubbornly it happen after strict typing. Okay. Nevertheless, I'd prefer a bit more information in the commit message. Here's my try: qapi: Modify docstrings to be sphinx-compatible I did not say "sphinx beautiful", just "sphinx compatible". They will not throw errors when parsed and interpreted as ReST. Finding a comprehensive style guide for our docstring utilization is left for another day. For now, use field lists recognized by Sphinx autodoc. FIXME link to their documentation > >>> >>> Signed-off-by: John Snow >>> --- >>> scripts/qapi/gen.py | 6 ++++-- >>> scripts/qapi/parser.py | 9 +++++---- >>> 2 files changed, 9 insertions(+), 6 deletions(-) >>> >>> diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py >>> index ca66c82b5b8..fc19b2aeb9b 100644 >>> --- a/scripts/qapi/gen.py >>> +++ b/scripts/qapi/gen.py >>> @@ -154,9 +154,11 @@ def _bottom(self): >>> @contextmanager >>> def ifcontext(ifcond, *args): >>> - """A 'with' statement context manager to wrap with start_if()/end_if() >>> + """ >>> + A 'with' statement context manager that wraps with `start_if` and `end_if`. >> Sadly, the fact that start_if() and end_if() are functions isn't >> immediately obvious anymore. >> I've seen :func:`start_if` elsewhere. Is this something we should >> or >> want to use? >> > > We *could*. > > `start_if` relies on the default role, which I have provisionally set > to "any" here, so this is shorthand for :any:`start_if`. > > The :any: role means: "cross-reference any type of thing." If there is > not exactly one thing that matches, it results in an error during the > documentation build. > > I like this, because it's nice short-hand syntax that I think > communicates effectively to the reader that this is a symbol of some > kind without needing a premium of ReST-ese. > > CONSTANTS are capitalized, Classes are title cased, and functions are > lower_case. `lower_case` references can be assumed to be functions, `lower_case` could also refer to an attribute, variable, or parameter. > but I will admit that this is not enforced or necessarily true as we > add more cross reference types in the future. > > (I am trying to add QMP cross-reference syntax!) > > I still prefer `start_if` to :func:`start_if` simply because it's less > markup and is easier to read in plaintext contexts. You're right, it > doesn't look like a function anymore. Yes, :func:`start_if` is rather heavy. I asked because I wanted to understand what :func: buys us. Not meant as endorsement. GDK-Doc seems smart enough to recognize start_if(). Sphinx isn't, because it's built around reST syntax. We put our money on the Sphinx horse, so... > I'm not sure if another annotations would work -- `start_if`() or > `start_if()`. Both seem kind of clunky to me, to be honest. Personal > feeling is "not really worth the hassle." You later reported the latter works. I prefer `start_if()` to `start_if`. Matter of taste. > >>> - *args: any number of QAPIGenCCode >>> + :param ifcond: List of conditionals >>> + :param args: any number of `QAPIGenCCode`. >>> Example:: >>> diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py >>> index 9d1a3e2eea9..02983979965 100644 >>> --- a/scripts/qapi/parser.py >>> +++ b/scripts/qapi/parser.py >>> @@ -381,10 +381,11 @@ def append(self, line): >>> The way that the line is dealt with depends on which >>> part of >>> the documentation we're parsing right now: >>> - * The body section: ._append_line is ._append_body_line >>> - * An argument section: ._append_line is ._append_args_line >>> - * A features section: ._append_line is ._append_features_line >>> - * An additional section: ._append_line is ._append_various_line >>> + >>> + * The body section: ._append_line is ._append_body_line >>> + * An argument section: ._append_line is ._append_args_line >>> + * A features section: ._append_line is ._append_features_line >>> + * An additional section: ._append_line is ._append_various_line >>> """ >>> line = line[1:] >>> if not line: >> I understand why you insert a blank line (reST wants blank lines >> around >> lists), I don't understand why you indent. Can you explain? > > I was mistaken about it needing the indent! Easy enough to tidy up :)