Excerpts from Zane Bitter's message of 2014-11-06 15:35:09 -0800: > On 06/11/14 20:44, Steven Hardy wrote: > > On Wed, Nov 05, 2014 at 02:46:43PM +0000, Lee, Alexis wrote: > >> I'm considering adding a function which takes a list and returns the > >> first > >> > >> non-null, non-empty value in that list. > >> > >> So you could do EG: > >> > >> some_thing: > >> > >> config: > >> > >> ControlVIP: > >> > >> first_nonnull: > >> > >> - {get_param: ControlVIP} > >> > >> - {get_attr: [ControlVirtualIP, fixed_ips, 0, > >> ip_address]}]} > >> > >> > >> I'm open to other names, EG "some", "or", "fallback_list" etc. > >> > >> Steve Hardy suggested building this into get_attr or Fn::Select. My > >> feeling is that those each do one job well right now, I'm happy to > >> take a steer though. > > > > Ah, from our IRC discussion I was thinking you wanted primarily list > > filtering of get_attr output, thus thinking an optional argument would make > > more sense than a new function. > > > > I see now that you're actually looking for something of a poor-mans > > conditional, so you choose either the ControlVIP parameter, or the > > ControlVirtualIP attribute, for which your proposal is probably cleaner - > > my concern is just that we avoid a proliferation of different list > > select/filter functions, when we could just have one. > > > Crazy thought: why not just implement conditionals? We had a proto-spec > for them started at one point... >
The coalesce/first_nonnull is just a shortcut for a common conditional problem. I'd agree that conditionals are useful as well, but they might be better served by more time to bake than this more narrow case. _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev