script.txt

1. Alien Basics
   * Teaser
       - Greetings
       - I can see your dilema already
       - You're sitting down tow write a Perl module
       - And you have some external dependencies
       - Maybe it's a C library
       - It could be a rust crate
       - Possibly some old Fortran library
       - It could even be something new and shiney written in Go
       - Either way you need this thing to install from CPAN for your users
       - Without causing them any trouble
       - You want the dependencies to just work
       - What are you going to do?
       - I'll tell you what you are going to do,
       - You are going to use some Alien Technology Now
       - *TAG*
   * Define Alien
       - [slides]
   * Why Alien?
       - [slides]
   * Alien Flowchart
       - [slides]
   * Alien Dependency
       - [slides]
   * Demo: create Alien::libarchive

       * We're going to start by installing libffi and libarchive.
       * These can be installed as Aliens without the system packages,
       * But this will speed things up.

       - sudo apt-get update && sudo apt-get install libffi-dev libarchive-dev

       * Next we're going to install Task::AlienDev, which will include
       * The Alien::Build framework, and a number of development tools
       * For creating Aliens.

       - cpanm -n Task::AlienDev

       * It takes a little time, but
       * Our development environment is now ready

       ## CUT ##

       * I realize it is contraversial, but I am going to recommend using Dist::Zilla
       * For Alien development.

       * This is because the Alien Dist::Zilla plugins handle a number of tricky edge cases
       * And will help you avoid common pitfalls.

       * You can create Aliens without Dist::Zilla and that is supported by
       * The Alien::Build framework
       * But for simplicity, I am going to use dzil in this demo.

       * We can mint a brand new Alien dist using the dzil new command,
       * And the AlienBuild minting profile.

       - dzil new -P AlienBuild Alien::libarchive

       * This will prompt for the URL to the tarball of the alienized package
       + http://libarchive.org/downloads/libarchive-3.5.2.tar.gz
       * The minting plugin will download the tarball from the internet and use it to guess a number of settings
       * We're going to mostly use the defaults.
       
       - cd Alien-libarchive

       * Now lets take a look at what has been created for us.

       - ls

       * The main Perl module doesn't contain any of its own code.
       * All of the heavy lifting is done in the base class Alien::Base.

       - less lib/Alien/libarchive.pm

       * The other generated file that is interesting is the alienfile.
       * This is a recipe for how to probe or install the alienized package.
       * For a well behaved autoconf or cmake project you may not have to make any changes at all.

       - less alienfile

       * Now lets test our newly minted dist.

       - dzil test

       * As you can see the Alien was able to find the system libarchive
       * And the test script displayed the compiler and linker flags
       * We will need a more complete test to ensure that the Alien works with both XS and FFI

       my $xs = <<EOF;
       #include "EXTERN.h"
       #include "perl.h"
       #include "XSUB.h"
       #include <archive.h>

       MODULE = main PACKAGE = main

       const char *
       archive_version_string()
       EOF

       xs_ok $xs, with_subtest {
         my $version = archive_version_string();
         ok $version;
         note $version;
       };

       ffi_ok { symbols => ['archive_version_string'] }, with_subtest {
         my($ffi) = @_;
         my $get_version = $ffi->function( archive_version_string => [] => 'string' );
         my $version = $get_version->();
         ok $version;
         note $version;
       };

       * We want to also make sure that it works as a share install
       * So we can use the environment variable ALIEN_INSTALL_TYPE to force a share install.

       - env ALIEN_INSTALL_TYPE=share dzil test

       * This takes a bit longer since we have to build from source,
       * But when complete,
       * We can see the test script display the compiler and linker flags
       * This time using the share location.

       * Next time we will cover how you can use your
       * Shiny new Alien.
   * Conclusion
       - Now you are an expert on Perl's Alien Technology
       - Tell me what Aliens are you going to write and contribute to CPAN
       - Please let us know by commenting in the section below
       - If you have any questions about Perl's Awesome Alien Technology
       - Please join us on pound native channel on irc.perl.org
       - If something goes wrong,
       - Don't panic,
       - Just open a ticket on our GitHub
       - Until next time, I will see you later.