[cfe-dev] scan-build man page

David Röthlisberger david at rothlis.net
Thu May 10 03:36:13 PDT 2012

Hi James

Don't let yourself be discouraged by these people expecting some kind of "perfect" solution... it is far too hard to get even the smallest change in, but do persevere. :-)


On 7 May 2012, at 22:36, James K. Lowden wrote:
> On Mon, 07 May 2012 10:21:01 -0700
> Ted Kremenek <kremenek at apple.com> wrote:
> Hi Ted, 
>> The man page looks really great.  
> Thanks.  I'm glad to start a conversation with it.  
>> My main concern, however, is
>> supporting divergent documents.  Ideally we want the documentation
>> for scan-build, the man page, etc., to all be in sync.  
> Having maintained a 90-page user guide for 10 years, I understand that
> concern.  I want to suggest, though, that "keeping it in sync" not as
> big a deal as most people think.  Documentation is not very redundant
> because it's labor-intensive, and labor, as you know, is scarce.
> Therefore overlap is inherently self-limiting.  
> Documentation is also not amenable to automation.  We want it to be; we
> want the code to be self-documenting.  And good code (by definition)
> is self-documenting.  But what we want from documentation isn't *in* the
> code (or shouldn't be).  It has to be written.  Asking for
> self-generating documentation is a bit like asking for self-generating
> code.  
> That said, the most tedious part of maintaining a reference manual is
> documenting all the options and ensuring 1) all options are documented
> and 2) all documented options are implemented.  Keeping the man page
> synchronized with the implementation can, in principle, be automated.
> But it doesn't follow that the man page must therefore be generated,
> even in part; it might be better simply to have a system that compared
> the two and reported on the differences.  For a small number of man
> pages, that "system" might be just eyeballs, and some vigilance when
> options are added/deleted.  
>> My main concern about having a separate man page file is that someone
>> is now responsible for keeping it up-to-date.  
> True.  Documentation even introduces bugs, because undocumented
> functionality never contradicted observed behavior.  ;-)
>> It's a bit of engineering, but I'd prefer we go in a direction where
>> the man page and the scan-build documentation on the website (or at
>> least part of it) were machine generated from some common description
> I would like to convince you that's both unnecessary and infeasible.  
> First, it's an optimization of labor with labor, right?  And the rule
> for optimization is to measure first.  How much do the man page and the
> website have in common?  I don't see much, nor need for more.  
> Even the obvious overlap -- command-line options -- doesn't warrant
> wholesale duplication.  A guide properly presents some of the
> options in an order chosen for ease of learning.  Rather than interrupt
> the text with an exhaustive list of every option and its synonym, a
> guide serves the user better by referring him to the reference manual
> for complete details.  As soon as you're selecting *some* options in a
> pedagogical order, you might as well just do it by hand.  The time
> spent getting that information into a back-end database and building
> the integration system will never be repaid.  
> Keep in mind Vint Cerf's dictum, too.  If you reject documentation
> because it's not in the "right" form, you restrict the number of
> contributors.  Not everyone willing and able to document will be
> interested in learning a specialized technology to do so.  
>> It sounds like you had a fairly mechanical process for generating the
>> man page (you took scan-build's output and manually post processed
>> it).  Do you think we could automate this with a script, so the man
>> page could just be a product of the build?  
> Mechnical, yes, but it can't be automated.  The text from scan-build
> lacks the very markers I added: the headings, that "model" is an
> argument, that [=title] is optional, and so on.  
> In principle the text could remain embedded in scan-build and extracted
> to generate a man page.  But you'd have to re-invent half of -mdoc in
> the process, without any improvement in the outcome.  Perldoc is a
> good example.  
>> Alternatively, since scan-build generates most of this text, maybe it
>> could generate the options part of the man page itself (as an option
>> to its output format), and have that output concatenated with some
>> common preamble.  What do you think?
> I would remove the help text from scan-build.  You don't need it
> anymore.  "man scan-build" is easier to use, and everyone knows how.
> Maintaining the man page is trivial next to the effort that goes into
> the scanner.  
> Besides, I'm allergic to so-called "help" that scrolls off my screen
> and destroys the 23 lines of context I had before it took over.  Be
> warned: for reasons science has been totally unable to explain, that
> allergy has been observed to be contagious.  I think I got it from
> Subversion.  
> Someone will be tempted to suggest that if the documentation is amid
> the code, the programmer will be more likely to keep it up to date.
> That proposition is contradicted by vast collective experience.  We both
> know huge projects with enviable (never perfect) documentation
> maintained as man pages.  I don't know of any that owe their
> documentation to how easy it is to maintain.  
> Again: I do think that reference documentation can and should be
> synchronized with the code.  Better tools could make that more
> convenient than anything available today by reducing redundancy, by not
> requiring, for instance, that function and argument names be restated.
> Clang promises to make that possible for C++.  It's one of the reasons
> I'm interested.  
> Regards, 
> --jkl
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