Pod::Manual Starring in the Timeless Classic "It's a Wonderful PDF"
Pod::Manual Starring in the Timeless Classic "It's a Wonderful PDF"
(Apologies for the truly terrible blog entry title. The Holiday season's tv programmation is somewhat corrupting me.)
Pod::Manual was born a little bit more than three years ago (three years? Egad, times does fly...), and because of a severe lack of tuit, kind of lingered in alpha-land ever since. But now, thanks to the Holidays and a long vacation stretch, I had the opportunity to return to the project and do terrible things to it. The code is even more alpha than it was before, and it's now in a post-hack shamble, but at least it has been moosified and (or so I hope) pushed in the right direction.
Good sir, it's been 3 years. We could use a recap.
Oh yes, right.
Pod::Manual was created of my wish to print out nice manuals
out of the POD of big projects like Moose or
Catalyst. To do that, two big
steps are involved: gathering the raw material and transmutate it into
something that can be printed.
Step 1: Gather the manuscripts
Perl's POD system serves us well for the one module = one manpage model, but for bigger distributions having quite a few documentation pieces, it has its weaknesses. To wit:
- No order or hierarchy between documents
- This is no problem for distributions that have a mere handful of modules, but
a first glance at, say, Moose is more daunting. Which
documentation should I read first? Which one is important for a user? For
someone who want to play with the guts of the system? Usually, the problem is
solved by having a
Foo::TableOfContentpod document thrown in the mix, but it'd be nice to have a way to physically gather together the different documents into a big one (or several big ones aimed at different audiences).
- Repetitive sections
While it makes sense to have the
COPYRIGHTsections present in the documentation of every module of a distribution, they sure become great paper-wasters when they are printed out. Wouldn't be great, for a paper version of the PODs, to just skip over sections that we don't care about (say the
VERSIONthat is being printed on the cover page anyway)? And for sections that we do care about, but that don't change between PODs of a same distribution, maybe it would make sense to print it only once, in an appendix?
- No table of content
- Unfortunately, paper doesn't offer full-text searches. In consequences, if a POD results in more than 40 printed pages, I usually find myself craving a table of content, with page number references. And, likewise, I want my pages numbered, with titles and stuff in the headers and footers.
Building the manual
And that's where
Pod::Manual fits in. Let's say that I want to build a
manual for Dist::Zilla. Then I could do:
Let's go over that again, in a more detailed fashion.
What I did was to first create the
Pod::Manual::DistZilla that inherits from
Pod::Manual. (Mind you,
creating a subclass is not strictly necessary, but it helps re-use and, as
we'll see in a few lines, allows for a nifty trick with
use Module::Pluggable search_path => ['Dist::Zilla::Plugin'];
Then, because we're using a class, I'm grabbing the singleton instance for it.
my $manual = PACKAGE->master;
I assign the title of the manual.
I don't want to see the
$manual->ignore( ['VERSION'] );
And I want to have one instance of the
COPYRIGHT AND LICENSE section
punted to the appendix (with the rest being ignored).
$manual->moveoneto_appendix( ['COPYRIGHT AND LICENSE'] );
That done, I can now add the main
Dist::Zilla modules I want to see in the manual.
$manual->add_module( [ qw/ Dist::Zilla Dist::Zilla::Tutorial / ] );
Because I can't resist being a cleaver monkey, I used
Module::Pluggable to throw in all the
Dist::Zilla::Plugin::* modules that I have installed on my
machine. But since those modules might be coming from other
distributions than the core
Dist::Zilla, I don't want to ignore
COPYRIGHT sections for them.
$manual->ignore(  ); $manual->moveoneto_appendix(  );
$manual->add_module( [ $manual->plugins ] );
Finally, we drop a
$manual; as a last piece of cleverness. As
true, our code can be used as a normal module:
my $manual = Pod::Manual::DistZilla->master;
or used with
do if we don't want to install the module or play with
my $manual = do 'path/to/DistZilla.pm';
(That's going to be useful later on to make the command-line interface as supple as possible.)
Step 2: Warm up the printing press
At the core: DocBook
Now we have our manual object, but we still have to output it in some
Pod::Manual is using
DocBook as its base format, and we can
get to it by doing:
Or, if we have a
css file that we want to associate to the resulting
print $manual->as_docbook( css => '/path/to/file.css' );
DocBook is nice as a starting point, but let's not forget that our
end-goal is to have something printable, like a
The tricky part with that, though, is that not only the roads to get
XSLT stylesheets and transformation engines,
LaTeX, etc) that
might or might not be present on any given machine.
Trying to implement a single transformation method would probably doom
Pod::Manual to work only on my own system. So I decided to take the plugin
approach instead. Manual formatters are roles that can be slapped on
Pod::Manual classes, and should provide a
as_format and/or a
saveasformat method. That way we can let the user who want
to generate the manual pick himself the roles he'll need to get there.
To be nice, we can even provide a little command-line utility script
that can do that for us:
A first PDF formatter using Prince
For a first way to get to the golden
Prince is not free,
they do offer a free version of it for non-commercial uses which
add a little icon on the first page -- something I can quite live with.
Its main appeal -- beside the gorgeous output it produces -- is the
css stylesheet is required
and the little translation engine does all the magic.
So what I did was to encapsulate the work in
And now, provided that
prince is installed on our machine, we can generate
$ podmanual --formatter=PDFPrince \ --as=pdf \ --output=dist-zilla-prince.pdf examples/dist-zilla.pl creating d.pdf... done
PDF the good ol' Knuth fashioned way
For those who prefer good old
LaTeX processing, I'm also
working on upgrading the powerful, but slightly eldritch
That's a topic for another blog entry, but once I'm done, we'll be able to get
LaTeX output by doing
$ podmanual --formatter=LaTeX --as=latex \ --output=dist-zilla.latex examples/dist-zilla.pl
and use it to generate the
$ podmanual --formatter=LaTeX,PDFLaTeX --as=pdf \ --output=dist-zilla.pdf examples/dist-zilla.pl
What Lies Ahead
A heck of a lot of work lies ahead. The hardest part if to juggle through the different formats. In some cases (cough LaTeX cough), I have to get reacquinted with it as it's been a very long while since I last used it. And then there's fiddling with the code such that doesn't look too much like the logic wasteland it currently is. Oh yes, and there's that documentation thing I should also do at some point.
Buuut I wanted to share the work of the last few days, just to let the people
that have been looking around for a fresher copy of the
manuals I'd generated the first time around know that there's reason to hope
that a new version of those should be available in a not-so-distant future.