How to Redistribute Non-core Modules in Perl?

Question

I am relatively new to Perl and I need some help with redistributing the non-core modules. Here's the whole story.

There are two non-core modules that were used in the Perl script: XML::Simple and SOAP::Lite. The version that I'm using (currently on Windows) is Strawberry Perl, so these two modules are already included. However, we don't know if the end users (Unix/Linux system) have these two modules as they might only have the standard version and so have only the core modules. My goal is to make the end users do as little configurations/installs as possible.

First, I tried to see if there's any core modules that's similar to XML::Simple and SOAP::Lite. Unfortunately, I didn't find any (Please correct me if I'm wrong).

So I guess now the only option is to redistribute the two modules. I checked and that these two modules allow redistribution. My problem right now is how to do it. I tried googling with keywords "perl redistribute" but didn't find anything useful. My guess is that we use the exporter tool to achieve this. but these two modules are rather complicated modules and they have several nested folders/pm files (and a whole bunch of other files like MAKE, pod, ini files) so I'm not sure what I should do. The examples I found using exporter are rather simple: They only have 1 pm file and 1 pl file and they are placed into one folder.

Also, I'm open to any other better ways to deal with the problem. The goal is just to make sure all end users can use my script with the least configuration/install efforts as we don't want them to run into a whole bunch of compatibility issues.

Any help would be appreciated. Thanks! =D

Answer 1

One of the best things about Perl is The CPAN, the Comprehensive Perl Archive Network. It's a mirroring service that since about the time Perl 5 originally came out has allowed people to share useful add-on modules, like XML::Simple or SOAP::Lite through a standard, common tool, the cpan client that comes with Perl. Almost all Perl distributions (such as Strawberry Perl and most Perl distributions that come with linux) have a CPAN client configured and included with them. This client lets people download and install modules from CPAN simply by knowing the name of the module.

Almost all module distributions on CPAN follow the exact same layout. They usually have a Makefile.PL file (if it uses ExtUtils::MakeMaker to generate the install script), Build.PL file (if it uses Module::Build to generate the install script), or both. These Perl scripts, once run, create a 'Makefile' or a 'Build' file that can let you install the module and verify that all prerequisites are met.

If you've never made a Perl distribution before, you can download any distribution you want from CPAN and take a look at how things are laid out. The folders and file locations are pretty intuitive once you've seen one. They are usually laid out with the install script and supporting files (like a readme) in the root directory, with the custom modules (modules you make) in the lib directory, and with unit tests in the t directory.

I'd recommend looking at the Build.PL based ones if you're a novice; these are pure Perl based install scripts. If you decide to make a Module.PL based distribution, it's really easy to specify that your module distribution needs XML::Simple and SOAP::Lite. First, create a basic Module::Build based install script. This looks something like:

use Module::Build;
my $build = Module::Build->new(
    module_name => 'Foo::Bar',
    license  => 'perl',
    requires => {
        'perl'          => '5.6.1',
        'Some::Module'  => '1.23',
        'Other::Module' => '>= 1.2, != 1.5, < 2.0',
    },
);
$build->create_build_script;

(This is taken right from the Module::Build::Authoring docs).

Then, specify the libraries you need and minimum versions of them. Zero (0) is an acceptable version if you don't care, but that means "anything" is good. I'd recommend specifying at least the version of the libraries installed on the machines you're testing with.

(Neat short cut: you can find out the version of any library that has a $VERSION package variable defined by doing:

perl -MSome::Lib -E "say Some::Lib->VERSION()"

.)

To install the module, the steps look something like this:

cd folder\where\my\lib\is
perl Build.PL
Build
Build test
Build install

This will create the install tool, prepare the folder for testing (usually just copying stuff to a build library area for simple modules), run all .t scripts in the t folder (the "tests", which usually use Test::More for unit testing of the module prior to install), and then finally, install your module to your PC's Perl site libraries.

The Build script, as part of the 'setting things up' phase, will look at your prerequisites, and warn you if you don't have them yet.

Then, as pointed out in ikegami's answer, if you use the cpanm client to install your library, the cpan client will automatically go out, download, test, and install your dependencies for you! Alternatively, Build.PL based installers also have the 'installdeps' option, which will do the same thing. Then any and all dependencies (and potentially recursive dependencies) are automatically downloaded, tested, and installed, even if they change in the future.

Answer 2

I want to elaborate a little bit on @ikegami said.

SOAP::Lite has a large number of CPAN dependencies, so the people installing your module are going to need CPAN access to get it to build, whether you provide it for them, or list it as a dependency. Otherwise, you'll need to provide your entire dependency tree, at which point, you end up using perlbrew, maybe carton, possibly local::lib, and then you might decide you need the next higher level and produce RPMs and DEBs.

Probably better to just provide your script, packaged as a CPAN module, list your dependencies within, and let the chips fall where they may.

Answer 3

Just state a dependency on the modules in your Makefile.PL or Build.PL, then give them the following installation instruction:

cpanm script.tar.gz