Genesis is the next version of archgenxml . I used to call it agx 2.0, but I've since been cured of my evils :-)
Daniel Nouri stirred up the conversation on the archetypes development mailinglist this afternoon, prompting me to finally write down the architecture a bit. Good thing he did it.
Genesis has two basic steps: reading and writing. Reading the input UML file and putting it into an internal model. And secondly writing out the actual product from that internal model to the filesystem. Simple, huh?
There are some configuration possibilities to steer this process. Of course some commandline or config file parameters for setting some global options. More directly important are the profiles and the generator.
You can define your UML stereotypes and tagged values in a profile. Such a profile of course forces you to document those items, so that we won't ever have the bad undocumented days back! It is possible to mix profiles, so you can have a plone 2.1 profile plus a Membrane profile.
The stereotypes defined in your profile(s) change the classes in the
internal model. Instead of only providing an
interface, they now also provide, say, a
interface. This will be used by the subsequent generator step.
Did I mention that you can make your own profiles? You've got to add support for it in the generator, too. This gives you previously unknown customisation possibilities :-)
For a certain profile, say plone 2.1, there are a number of fixed
files and directories that need to be generated. The generator tries
to create them and actively pulls information from the internal
model. An adapter for the main model element might be best
here. This gives you the
Extensions/install.py for instance.
The second step is for the internal model to push all items to the
generator and have the generator slug it out. There has to be a
configuration file that tells the generator that for every incoming
IPloneClass, there should be an archetypes class, possibly a
template in the skins directory and so on.
All those little things like an
__init__.py file in every
directory are handled by creating it on every incoming
IPackage. The adapter itself can of course query the package for
contained items and calling an appropriate adapter that gives back
an import line.
The great thing here is that if you've got a certain class of item in the package for which you don't want an import line then you just need to provide an adapter for that interface that keeps quiet when asked for an import line.
So: genesis reads a file into an internal model, using one or more profiles. Those profiles customise the base genesis to your needs. It then uses a generator (which you again configure) to create your product.
Profiles, the generator configuration and adapters look set to making this pretty adaptable, maintainable and elegant.
The current code is nowhere near finished. About half of it is in the state that we left it when running for the train after September's castle sprint. I've done some work on a few parts. The parts that start to look a bit decent:
I've only recently started trying to wire it all together a bit, so stay tuned for more improvements. Jean-Paul Ladage plans on sitting with me for half a day a week to push it forward to get some basic functionality going before the golden roof sprint .
My name is Reinout van Rees and I work a lot with Python (programming language) and Django (website framework). I live in The Netherlands and I'm happily married to Annie van Rees-Kooiman.
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