Ship EHP Evaluator – The making of

As stated in my last post, making this tool was both easier and more difficult than I was expecting. I thought I’d explain that, and shed a little light on a couple of libraries that made this oh so much easier than originally expected.

The libraries in question are LibDogma and PHP-Dogma. These libraries meant that I didn’t have to think about what any modules did. I just tell them ‘This ship, these skills, these modules and rigs’ and I get back an answer saying ‘this hp, these resists’.

This is the core of any fitting tool, and what makes writing fitting tools so much, umm, fun. So many little caveats, the various stacking rules, and so on, and so on. Libdogma takes care of all of it. php-dogma lets me access libdogma from inside a php page.

With that out of the way, it was a straight run home, tying it into the code I’d already written for the evaluator to parse the input. And just a little for calculating and outputting the EHP. That’s the ‘Easier than expected’ bit.

The more difficult than expected comes from the expectations that I had, when I found libdogma. I’m using a Centos 6 server, which comes with gcc 3.4.4. That won’t compile libdogma. So I found an updated rpm and tried that. No dice.

Eventually I downloaded and compiled clang (the latest version) from source. That built libdogma fine, and it passed all the tests.

At which point php-dogma refused to compile. It appears to have been a problem with php 5.3.27, as after an upgrade to 5.4, it all worked fine. And the first time I tried, I’d forgotten to set PKG_CONFIG_PATH, so it didn’t find libdogma. Took me a little time to run that one to ground.

Short sentences, to cover quite a lot of time banging on things, and hoping they’d work.

Anyway, as php-dogma is agpl, I’ve released the code on github under the agpl as well. Short version, if you don’t know the license: Add it to what you want, but if you let people use it, then you have to let them have access to the source, including if it’s as a service. Obviously, IANAL, so you’ll want to look at the license in more detail, if you’re not happy releasing your code.