<div class="blog">
<h1 id="NAME">
-Why I will be sticking to CPAN
+The Build Process of SDL Perl
</h1>
<div class="CONTENT">
-<div style="text-align: right;"><i>sculpted in clay,</i></div><div style="text-align: right;"><i>then fired to glass.<br /></i><i><br /></i></div><br />Recently there was really long <a href="http://www.nntp.perl.org/group/perl.sdl.devel/2009/09/msg1424.html">discussion </a>on sdl-devel@perl.org about providing packages for SDL perl rather than focusing on CPAN releases. The gists of the argument was that SDL perl should be making platform specific packages for end users. I agree with this idea but I do have to face the truth. <br /><br />The truth is there are very few developers currently working on SDL Perl. The truth is CPAN provides several tools that which currently drives development for SDL Perl. There are people interested in packaging SDL Perl (<a href="http://rt.cpan.org/Ticket/Display.html?id=49003">kmx</a>, <a href="http://www.nntp.perl.org/group/perl.sdl.devel/2009/09/msg1433.html">jean</a> and Jerome Quelin). The truth is there are other very <a href="http://rt.cpan.org/Ticket/Display.html?id=49084">critical areas</a> we can focus on. <br /><br />If there are people looking to package SDL Perl for their platform please contact us at sdl-devel@perl.org.<div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/3102167581424744259-6565605958523853965?l=yapgh.blogspot.com'/></div></div></div>
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+<p>A while ago I had a long chat with mst on why SDL uses Module::Build rather then Make. I told him it is a simple matter of code inertia. The existing Module::Build system has worked well for us so far. Never the less, he convinced me that switching to Make will improve debugging the Build system. But to be able to switch we will need to completely replace the Build system. I am not prepared to do that so I will just present the requirements so mst or someone else can at least attempt to switch.</p><br />
+<br />
+<h3>The Build Process </h3><br />
+<b> Alien::SDL </b><br />
+<br />
+<p>SDL Perl depends on a few C libraries for a complete install. This is handled by Alien::SDL. First we look for existing SDL libraries and dependencies by doing a <a href="http://github.com/kthakore/Alien_SDL/blob/master/inc/My/Utility.pm#L581">File::Find</a> for headers. If these headers are found we present and option for the user to use those. We then store these locations in Alien::SDL->config options 'cflags', 'prefix' and 'libs'. If we do not have libraries available even for a minimum SDL installed ( SDL.h is not found). We provide several platform specific options. </p><br />
+<p>For windows we have a simpler process. We download<a href="http://github.com/kthakore/Alien_SDL/blob/master/inc/My/Utility.pm#L7"> prebuilt </a>binaries ( and checksum ) based on the user's selection and just copy them in to the right location. Again the 'prefix', 'cflags', and 'libs' is saved in Alien::SDL->config. </p><br />
+<p>For *nix/MacOSX we download sources and attempt to compile them. To be able to do this we download several other dependencies like libpng, jpeg and pango. You can see how we do this using hashes <a href="http://github.com/kthakore/Alien_SDL/blob/master/inc/My/Utility.pm#L404">here</a>. During the compile process we also apply patches as needed for the <a href="http://github.com/kthakore/Alien_SDL/blob/master/inc/My/Utility.pm#L430">sources</a>. Once this is done we can head to SDL Build.PL </p><br />
+<b> SDL Perl dependency resolution </b><br />
+<br />
+SDL's Build is responsible for linking the right libraries to the correct XS. If libraries are missing it will disable the component (not put it in SDL->config). <br />
+<br />
+<p>For example to build <a href="http://github.com/kthakore/SDL_perl/blob/master/Build.PL#L342">Image.xs</a> we require libsdl, libsdl_image and lib[jpg|png|tiff]. So we would check for these headers in the prefix provided by Alien::SDL->config. If they are not provided we will disable the SDL::Image module. </p><br />
+<p>More over the availability of each library is specified as a -DMACRO to the gcc compiler. This way we can prevent XS failures due to missing libraries using #DEFINES. Here the SDL_image macro is <a href="http://github.com/kthakore/SDL_perl/blob/master/Build.PL#L422">defined</a> and <a href="http://github.com/kthakore/SDL_perl/blob/master/src/Image.xs#L13">used</a>. The availability of the module is then available from <a href="http://github.com/kthakore/SDL_perl/blob/master/t/image.t#L20">SDL::Config->has()</a> <br />
+<br />
+<br />
+<b> Conclusion </b> <br />
+<p>This is a high level overview of our Build process, because frankly I hate traumatizing my brain with this again. Credits have to go to FROGGS and kmx for helping with this Build scheme. Hopefully my post have helped people at the very least appreciate the problem scope of this Build system. That said I believe a fresh written build system, with these requirements in mind, will be more then welcome.<br />
+</p><div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/3102167581424744259-4514794130108689562?l=yapgh.blogspot.com' alt='' /></div>
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