{"id":1648,"date":"2011-08-22T00:11:45","date_gmt":"2011-08-21T23:11:45","guid":{"rendered":"http:\/\/t-machine.org\/?p=1648"},"modified":"2015-12-31T18:35:10","modified_gmt":"2015-12-31T17:35:10","slug":"entity-system-rdbms-beta-a-new-example-with-source","status":"publish","type":"post","link":"http:\/\/new.t-machine.org\/index.php\/2011\/08\/22\/entity-system-rdbms-beta-a-new-example-with-source\/","title":{"rendered":"Entity System: RDBMS-Beta (a new example with source)"},"content":{"rendered":"

I’ve just added a new, improved Entity System design<\/a> to the wiki. I’ve also created a github project for it<\/a> where I’m about to check-in working source.<\/p>\n

The only source I’ve provided is Java – but it’s an evolution upon the old “RDBMS with Code in Systems” type<\/a>, that already has full source for Java and Objective-C – so you could easily upgrade the obj-c version to this new type (hint, hint).<\/p>\n

What’s new?<\/h3>\n

Three major changes:<\/p>\n

    \n
  1. Included a bunch of sensible java-specific improvements, based on the forks other people had done of the previous Java implementation\n
  2. Added a bunch of FANTASTICALLY USEFUL methods to the EntityManager – things you definitely need when writing a game\n
  3. Added a new concept: the Meta Entity\n<\/ol>\n

    The first one is obvious, the second is obvious when you look at what’s added (e.g. a “removeComponent” method; why wasn’t it there originally? Solely because it wasn’t necessary to show “the simplest possible implementation”).<\/p>\n

    The interesting one is number three: the Meta Entity<\/p>\n

    What’s a MetaEntity?<\/h3>\n

    A while back, in the first Java\/Android ES I wrote about<\/a>, I mentioned that I was using a fake Entity class.<\/p>\n

    I made a big fuss about how this was NOT being used to store any game data – but was instead an OOP trick to make it easier to write code.<\/p>\n

    Thinking about this later, I realised that there was really no need for that class to be named “Entity” – and calling it that ran the risk of tempting people into using OOP for their core data \/ components (Remember: Never do that!). Instead, looking back at a couple of example ES’s I’d written, I saw that every method – and all data – in this class was a “meta method”.<\/p>\n

    For the methods, you need to read the source AND the javadocs to see this.<\/p>\n

    For the data, it’s a lot more obvious: the only data that a MetaEntity has is:<\/p>\n