On 23/02/11 07:05, Luke Kanies wrote:
> I thought this design point would be interesting, assuming I can make
> it sufficiently clearly.
>
> I just did a refactor of my Interfaces work - previously, I had a
> base class of Puppet::Interface, and all interfaces were subclasses
> of that class.
>
> However, once Dan Bode asked for a separation between interfaces that
> used the Indirector and those that didn't, I suddently had the base
> class, a new Puppet::Interface::Indirector class, and then subclasses
> of each. Then the code smell showed up.
>
> Basically, I had to mark the Indirector class as 'abstract', because
> it's not actually an interface, it's just another base class. Then I
> recognized the pattern that I've been trying to get away from - a
> base class heirarchy, then an instance class heirarchy, with almost
> no instance functionality in the whole chain.
>
> So, I converted the whole thing - Interface is still the base class,
> and Indirector is still a subclass, but all interfaces are just
> instances of one of those two (or any other subclass). It works
> essentially identically, other than initialization:
>
> Puppet::Interface.new :plugin do action :download do .... end end
>
> But I'm also defining all of the appropriate constants, so adding
> actions can be done the same way:
>
> Puppet::Interface::Plugin.action :foo { ... }
So that means each interface instance is essentially a singleton, is
that right?
> As to benefits, primarily it's about general code maintainability.
> It was nearly impossible to determine if a given method was base
> class functionality, subclass functionality, instance functionality,
> or what. Here, it's all very clear and very simple.
I guess I should read the code, beacuse it doesn't look clear and simple
from here :)
> There are a few other places that need this same refactor -- notably
> Puppet::Type. Hopefully some day. :)
So, when will this be merged in the core (and will it be)?
I'm currently polishing my puppet instrumentation patch, which would
greatly benefit from using this interface layer for controlling the
instrumentation plugins. But I don't think I can send here a puppet core
patch that at the same time depends on external code (or could I?).
Thanks,
--
Brice Figureau
My Blog: http://www.masterzen.fr/
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