On Mon, Nov 18, 2013 at 1:58 PM, Christopher Armstrong <chris.armstr...@rackspace.com> wrote: > On Mon, Nov 18, 2013 at 3:00 PM, Dan Smith <d...@danplanet.com> wrote: >> >> Sorry for the delay in responding to this... >> >> > * Moved the _obj_classes registry magic out of ObjectMetaClass and >> > into >> > its own method for easier use. Since this is a subclass based >> > implementation, >> > having a separate method feels more appropriate for a >> > factory/registry >> > pattern. >> >> This is actually how I had it in my initial design because I like >> explicit registration. We went off on this MetaClass tangent, which buys >> us certain things, but which also makes certain things quite difficult. >> >> Pros for metaclass approach: >> - Avoids having to decorate things (meh) >> - Automatic to the point of not being able to create an object type >> without registering it even if you wanted to >> >> Cons for metaclass approach: >> - Maybe a bit too magical >> - Can make testing hard (see where we save/restore the registry >> between each test) >> - I think it might make subclass implementations harder >> - Definitely more complicated to understand >> >> Chris much preferred the metaclass approach, so I'm including him here. >> He had some reasoning that won out in the original discussion, although >> I don't really remember what that was. >> > > It's almost always possible to go without metaclasses without losing much > relevant brevity, and improving clarity. I strongly recommend against their > use. >
I think this is simple and to the point. ++ Metaclasses have their places, but it really makes it hard to clearly view what is going on in a straight forward manner. I would prefer to keep metaclass use limited (wherever possible) with the exception of abstract base classes (which are straightforward enough to understand). I think the plus of "avoiding decorating things" isn't really a huge win, and actually i think takes clarity away. --Morgan Fainberg _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
