Add autogeneration of perlmodlib.pod and the new perlnewmod.pod,

both from Simon Cozens.

p4raw-id: //depot/cfgperl@6161

1 files changed, 282 insertions, 0 deletions

diff --git a/pod/perlnewmod.pod b/pod/perlnewmod.pod
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+=head1 NAME
+
+perlnewmod - preparing a new module for distribution
+
+=head1 DESCRIPTION
+
+This document gives you some suggestions about how to go about writing
+Perl modules, preparing them for distribution, and making them available
+via CPAN.
+
+One of the things that makes Perl really powerful is the fact that Perl
+hackers tend to want to share the solutions to problems they've faced,
+so you and I don't have to battle with the same problem again.
+
+The main way they do this is by abstracting the solution into a Perl
+module. If you don't know what one of these is, the rest of this
+document isn't going to be much use to you. You're also missing out on
+an awful lot of useful code; consider having a look at L<perlmod>,
+L<perlmodlib> and L<perlmodinstall> before coming back here.
+
+When you've found that there isn't a module available for what you're
+trying to do, and you've had to write the code yourself, consider
+packaging up the solution into a module and uploading it to CPAN so that
+others can benefit.
+
+=head2 Warning
+
+We're going to primarily concentrate on Perl-only modules here, rather
+than XS modules. XS modules serve a rather different purpose, and
+you should consider different things before distributing them - the
+popularity of the library you are gluing, the portability to other
+operating systems, and so on. However, the notes on preparing the Perl
+side of the module and packaging and distributing it will apply equally
+well to an XS module as a pure-Perl one.
+
+=head2 What should I make into a module?
+
+You should make a module out of any code that you think is going to be
+useful to others. Anything that's likely to fill a hole in the communal
+library and which someone else can slot directly into their program. Any
+part of your code which you can isolate and extract and plug into
+something else is a likely candidate.
+
+Let's take an example. Suppose you're reading in data from a local
+format into a hash-of-hashes in Perl, turning that into a tree, walking
+the tree and then piping each node to an Acme Transmogrifier Server.
+
+Now, quite a few people have the Acme Transmogrifier, and you've had to
+write something to talk the protocol from scratch - you'd almost
+certainly want to make that into a module. The level at which you pitch
+it is up to you: you might want protocol-level modules analogous to
+L<Net::SMTP|Net::SMTP> which then talk to higher level modules analogous
+to L<Mail::Send|Mail::Send>. The choice is yours, but you do want to get
+a module out for that server protocol.
+
+Nobody else on the planet is going to talk your local data format, so we
+can ignore that. But what about the thing in the middle? Building tree
+structures from Perl variables and then traversing them is a nice,
+general problem, and if nobody's already written a module that does
+that, you might want to modularise that code too.
+
+So hopefully you've now got a few ideas about what's good to modularise.
+Let's now see how it's done.
+
+=head2 Step-by-step: Preparing the ground
+
+Before we even start scraping out the code, there are a few things we'll
+want to do in advance.
+
+=over 3
+
+=item Look around
+
+Dig into a bunch of modules to see how they're written. I'd suggest
+starting with L<Text::Tabs|Text::Tabs>, since it's in the standard
+library and is nice and simple, and then looking at something like
+L<Time::Zone|Time::Zone>, L<File::Copy|File::Copy> and then some of the
+C<Mail::*> modules if you're planning on writing object oriented code.
+
+These should give you an overall feel for how modules are laid out and
+written.
+
+=item Check it's new
+
+There are a lot of modules on CPAN, and it's easy to miss one that's
+similar to what you're planning on contributing. Have a good plough
+through the modules list and the F<by-module> directories, and make sure
+you're not the one reinventing the wheel!
+
+=item Discuss the need
+
+You might love it. You might feel that everyone else needs it. But there
+might not actually be any real demand for it out there. If you're unsure
+about the demand you're module will have, consider sending out feelers
+on the C<comp.lang.perl.modules> newsgroup, or as a last resort, ask the
+modules list at C<modules@perl.org>. Remember that this is a closed list
+with a very long turn-around time - be prepared to wait a good while for
+a response from them.
+
+=item Choose a name
+
+Perl modules included on CPAN have a naming hierarchy you should try to
+fit in with. See L<perlmodlib> for more details on how this works, and
+browse around CPAN and the modules list to get a feel of it. At the very
+least, remember this: modules should be title capitalised, (This::Thing)
+fit in with a category, and explain their purpose succinctly.
+
+=item Check again
+
+While you're doing that, make really sure you haven't missed a module
+similar to the one you're about to write.
+
+When you've got your name sorted out and you're sure that your module is
+wanted and not currently available, it's time to start coding.
+
+=back
+
+=head2 Step-by-step: Making the module
+
+=over 3
+
+=item Start with F<h2xs>
+
+Originally a utility to convert C header files into XS modules,
+L<h2xs|h2xs> has become a useful utility for churning out skeletons for
+Perl-only modules as well. If you don't want to use the
+L<Autoloader|Autoloader> which splits up big modules into smaller
+subroutine-sized chunks, you'll say something like this:
+
+    h2xs -AX -n Net::Acme
+
+The C<-A> omits the Autoloader code, C<-X> omits XS elements, and C<-n>
+specifies the name of the module.
+
+=item Use L<strict|strict> and L<warnings|warnings>
+
+A module's code has to be warning and strict-clean, since you can't
+guarantee the conditions that it'll be used under. Besides, you wouldn't
+want to distribute code that wasn't warning or strict-clean anyway,
+right?
+
+=item Use L<Carp|Carp>
+
+The L<Carp|Carp> module allows you to present your error messages from
+the caller's perspective; this gives you a way to signal a problem with
+the caller and not your module. For instance, if you say this:
+
+    warn "No hostname given";
+
+the user will see something like this:
+
+    No hostname given at /usr/local/lib/perl5/site_perl/5.6.0/Net/Acme.pm
+    line 123.
+
+which looks like your module is doing something wrong. Instead, you want
+to put the blame on the user, and say this:
+
+    No hostname given at bad_code, line 10.
+
+You do this by using L<Carp|Carp> and replacing your C<warn>s with
+C<carp>s. If you need to C<die>, say C<croak> instead. However, keep
+C<warn> and C<die> in place for your sanity checks - where it really is
+your module at fault.
+
+=item Use L<Exporter|Exporter> - wisely!
+
+C<h2xs> provides stubs for L<Exporter|Exporter>, which gives you a
+standard way of exporting symbols and subroutines from your module into
+the caller's namespace. For instance, saying C<use Net::Acme qw(&frob)>
+would import the C<frob> subroutine.
+
+The package variable C<@EXPORT> will determine which symbols will get
+exported when the caller simply says C<use Net::Acme> - you will hardly
+ever want to put anything in there. C<@EXPORT_OK>, on the other hand,
+specifies which symbols you're willing to export. If you do want to
+export a bunch of symbols, use the C<%EXPORT_TAGS> and define a standard
+export set - look at L<Exporter> for more details.
+
+=item Use L<plain old documentation|perlpod>
+
+The work isn't over until the paperwork is done, and you're going to
+need to put in some time writing some documentation for your module.
+C<h2xs> will provide a stub for you to fill in; if you're not sure about
+the format, look at L<perlpod> for an introduction. Provide a good
+synopsis of how your module is used in code, a description, and then
+notes on the syntax and function of the individual subroutines or
+methods. Use Perl comments for developer notes and POD for end-user
+notes.
+
+=item Write tests
+
+You're encouraged to create self-tests for your module to ensure it's
+working as intended on the myriad platforms Perl supports; if you upload
+your module to CPAN, a host of testers will build your module and send
+you the results of the tests. Again, C<h2xs> provides a test framework
+which you can extend - you should do something more than just checking
+your module will compile.
+
+=item Write the README
+
+If you're uploading to CPAN, the automated gremlins will extract the
+README file and place that in your CPAN directory. It'll also appear in
+the main F<by-module> and F<by-category> directories if you make it onto
+the modules list. It's a good idea to put here what the module actually
+does in detail, and the user-visible changes since the last release.
+
+=back
+
+=head2 Step-by-step: Distributing your module
+
+=over 3
+
+=item Get a CPAN user ID
+
+Every developer publishing modules on CPAN needs a CPAN ID. See the
+instructions at C<http://www.cpan.org/modules/04pause.html> (or
+equivalent on your nearest mirror) to find out how to do this.
+
+=item C<perl Makefile.PL; make test; make dist>
+
+Once again, C<h2xs> has done all the work for you. It produces the
+standard C<Makefile.PL> you'll have seen when you downloaded and
+installs modules, and this produces a Makefile with a C<dist> target.
+
+Once you've ensured that your module passes its own tests - always a
+good thing to make sure - you can C<make dist>, and the Makefile will
+hopefully produce you a nice tarball of your module, ready for upliad.
+
+=item Upload the tarball
+
+The email you got when you received your CPAN ID will tell you how to
+log in to PAUSE, the Perl Authors Upload SErver. From the menus there,
+you can upload your module to CPAN.
+
+=item Announce to the modules list
+
+Once uploaded, it'll sit unnoticed in your author directory. If you want
+it connected to the rest of the CPAN, you'll need to tell the modules
+list about it. The best way to do this is to email them a line in the
+style of the modules list, like this:
+
+    Net::Acme bdpO  Interface to Acme Frobnicator servers         FOOBAR
+    ^         ^^^^  ^                                             ^
+    |         ||||  Module description                            Your ID
+    |         ||||
+    |         |||\- Interface: (O)OP, (r)eferences, (h)ybrid, (f)unctions
+    |         |||
+    |         ||\-- Language: (p)ure Perl, C(+)+, (h)ybrid, (C), (o)ther
+    |         ||
+    Module    |\--- Support: (d)eveloper, (m)ailing list, (u)senet, (n)one
+    Name      |
+              \---- Maturity: (i)dea, (c)onstructions, (a)lpha, (b)eta,
+                              (R)eleased, (M)ature, (S)tandard
+
+plus a description of the module and why you think it should be
+included. If you hear nothing back, that means your module will
+probably appear on the modules list at the next update. Don't try
+subscribing to C<modules@perl.org>; it's not another mailing list. Just
+have patience.
+
+=item Announce to clpa
+
+If you have a burning desire to tell the world about your release, post
+an announcement to the moderated C<comp.lang.perl.announce> newsgroup.
+
+=item Fix bugs!
+
+Once you start accumulating users, they'll send you bug reports. If
+you're lucky, they'll even send you patches. Welcome to the joys of
+maintaining a software project...
+
+=back
+
+=head1 AUTHOR
+
+Simon Cozens, C<simon@cpan.org>
+
+=head1 SEE ALSO
+
+L<perlmod>, L<perlmodlib>, L<perlmodinstall>, L<h2xs>, L<strict>,
+L<Carp>, L<Exporter>, L<perlpod>, L<Test>, L<ExtUtils::MakeMaker>,
+http://www.cpan.org/