fenics team mailing list archive

[Kristian Ølgaard <k.b.oelgaard@xxxxxxxxx>]

On 26 August 2010 19:51, Anders Logg <logg@xxxxxxxxx> wrote:
> On Thu, Aug 26, 2010 at 07:42:35PM +0200, Kristian Ølgaard wrote:
>> On 26 August 2010 18:22, Anders Logg <logg@xxxxxxxxx> wrote:
>> > I've thought some more on how to organize/synchronize the FEniCS
>> > documentation (in fenics-doc) with the documentation we have in the
>> > code.
>> >
>> > I think it is important that
>> >
>> > (1) the strings we have in the code are the same as those that appear
>> > on in the HTML documentation (which we write in Sphinx).
>> >
>> > (2) the strings we have in the code are short (so they don't clutter
>> > up the code)
>>
>> I disagree. The whole idea of the documentation effort was to document
>> in one place
>> (using carefully handwritten and elaborate explanations including
>> examples and links to demos etc.) and code in another.
>> The comments in the code should be very short and precise such that
>> together with the class/function definition and type info the
>> developer can complete the task without looking elsewhere. These kind
>> of comments, I expect, will look weird when put next to an elaborate
>> explanation on how the class/function works including all the bells
>> and whistles.
>>
>> > If we look at these two, it seems that (1) implies that we should
>> > write the documentation as part of the code and then extract it using
>> > some tool.
>> >
>> > But (2) prevents that since we don't want to constrain the
>> > documentation for all functions to be very short.
>> >
>> > How about the following solution.
>> >
>> > * Write short docstrings in the code
>> >
>> > * Auto-generate all the .rst input files for the Programmer's
>> >  Reference using a simple Python script that looks for '///'
>> >
>> > * The script looks at the code to generate the signature of the
>> >  function and the text that comes immediately after.
>>
>> This might be possible for a simple
>> 'change-order-of-comment-and-function' script where you manipulate the
>> output manually afterwards, but if you want to run this more than once
>> you will have to pick up nested class/struct definitions templates and
>> all kinds of crap.
>> I tried to write a parser like this to check if all classes and
>> functions were documented, but gave up and let Doxygen do the dirty
>> work. (But do we want to do this just to generate 20 characters of
>> docstring automatically?)
>>
>> >  But it also looks in a hand-written .rst file that contains any
>> >  additional stuff we want to put below.
>> >
>> > So for the code example in the style manual, the things that get
>> > picked up from the code are
>> >
>> >  // Return the cell which is closest to the given point
>> >  uint closest_cell(const Point & point) const
>> >
>> > which gets converted to
>> >
>> > .. cpp:function:: uint closest_cell(const Point & point) const
>> >
>> >    Return the cell which is closest to the given point
>> >
>> > The script also looks in a file for "closest_cell" below which we have
>> > written all the *Arguments* stuff that will be thrown in below.
>> >
>> > Will that work?
>>
>> Yes, but the work flow is getting complex, and you'll need to know
>> what you get from the source code so you don't repeat yourself.
>> It is much easier to have the documentation in one place.
>>
>> > Another solution would be to just write everything as part of the
>> > code, and just add some settings to our editors that will fold the
>> > extra stuff away so we don't need to see it. Maybe that is the most
>> > robust solution?
>>
>> The general consensus the last time this issue came up was not to
>> clutter the code with documentation markup.
>>
>> Kristian
>
> I agree it's good to have the documentation in one place, but it would
> be good if we found a way to keep it in sync. Helper scripts can do
> some of that work, but we probably won't be able to pick up things
> like having
>
>  "Compute the number of neighbors"
>
> in one place and
>
>  "Return the number of neighbors"
>
> in other places. Things like this will creep in over time. It might
> not be a big issue but I find it a bit annoying.

I see. A simpler approach, rather than generating docstrings would be
to have a script that
simply looks for '///' comments in dolfin/mesh/Mesh.h and check if the
EXACT same strings are present in
programmers-reference/cpp/mesh/Mesh.rst, if not crash test and let
user figure out manually why it failed and which comment/docstring
should be changed.
This won't be completely bulletproof, but much much simpler than
parsing a C++ library.
I currently check if the docstrings of the documentation for the
Python interface is equal to the docstrings of the DOLFIN module after
import so that sort of works in the same way, only in this case I know
that the docstring I check belongs to function 'bar' of class 'foo'.

Then we use the stub-generator that you have know to give us the first
set of *.rst files and then add the '///' comments check to the
verify_cpp_documentation.py script.

Kristian

> Won't we always have the documentation string (in .rst) start with a
> simple thing like this? "Return this or that", or "Compute foo based
> on...". Then a more elaborate explanation follows.

Probably, I just copied the docstrings which were already there.

Kristian

> --
> Anders
>