How do I start a new Perl module distribution?

Question

I'm trying to set up a large-ish project, written in Perl. The IBM MakeMaker tutorial has been very helpful so far, but I don't understand how to link all the modules into the main program. In my project root, I have MANIFEST, Makefile.PL, README, a bin directory, and a lib directory. In my bin directory, I have my main script (Main.pl). In the lib directory, I have each of my modules, divided up into their own respective directories (i.e. Utils::Util1 and Utils::Utils2 in the utils directory, etc). In each module directory, there is also a t directory, containing tests

My MANIFEST file has the following:

bin/Main.pl
lib/Utils/Util1.pm
lib/Utils/Util2.pm
lib/Utils/t/Utils1.t
lib/Utils/t/Utils2.t
Makefile.PL
MANIFEST
README

Makefile.PL is the following:

use ExtUtils::MakeMaker;
WriteMakefile(
    'NAME'=>'Foo',
    'VERSION_FROM'=>'bin/Main.pl',
    'PREREQ_PM'=>{
    "XML::Simple"=> 2.18}, #The libraries that we need and their
             #minimum version numbers
    'EXE_FILES' =>[("bin/Main.pl")]
);

After I make and run, the program crashes, complaining that it cannot find Utils::Util1, and when I run 'make test, it says no tests defined. Can anyone make any suggestions? I have never done a large scale project like this in perl, and I will need to add many more modules

Answer 1

By default, tests are looked for in a top-level t directory (or a test.pl file, but that has some limitations, so should be avoided).

You say "After I make and run"...make puts things into a blib directory structure ready to be installed, but doesn't do anything special to make running a script access them. (make test is special; it does add appropriate paths from blib to perl's @INC to be able to run the tests.) You will need to do a "make install" to install the modules where your script will find them (or use a tool like PAR to package them together with your script).

Answer 2

Try this structure:

bin/Main.pl
lib/Utils/Util1.pm
lib/Utils/Util2.pm
Makefile.PL
MANIFEST
README
t/Utils1.t
t/Utils2.t

As ysth said, make does not install your modules, it just builds them in a blib directory. (In your case it just copies them there, but if you had XS code, it would be compiled with a C compiler.) Use make install to install your modules for regular scripts to use.

If you want to run your script between make and make install, you can do:

perl -Mblib bin/Main.pl

The -Mblib instructs perl to temporarily add the appropriate directories to the search path, so you can try out an uninstalled module. (make test does that automatically.)

Answer 3

Might I also suggest module-starter? It'll automatically create a skeleton project which "Just Works". I learned what little I know about Perl modules organization by reading the generated skeleton files. It's all well-documented, and quite easy to use as a base for growing a larger project in. You can check out the getting-started docs to see what it gives you.

Running module-starter will give you a Perl distribution, consisting of a number of modules (use the command line option --module, such as:

module-starter --distro=Project --module=Project::Module::A,Project::Module::B [...]

to create multiple modules in a single distribution). It's then up to you whether you'd prefer to organize your project as a single distribution consisting of a number of modules working together, or as a number of distributions which can be released separately but which depend on each other (as configured in your Build or Makefile.PL file) to provide a complete system.

Answer 4

If you are just starting to create Perl modules (which is also Perl's equivalent of a project), don't use Makemaker. Module::Build is the way to go, and it's now part of the standard library. Makemaker is for us old salts who haven't converted to Module::Build yet. :)

You should never start off a Perl project by trying to create the structure yourself. It's too much work and you'll always forget something. For your first go, try something like Module::Starter, but if you are doing to do this quite a bit, you might then convert that to Distribution::Cooker so you can customize your files and contents.