I see - so, IIUC, the problem you are trying to solve really is the *replacement* of an existing config setting with an altogether new config setting?
In that case, I suppose, the proposed additional info may be used *if* we are required to ensure backward compatibility, although, I'm not sure if that is a mandatory requirement across major release updates (unless, of course, we encounter a need to make this sort of change across a minor release update?). > On Nov 21, 2016, at 2:18 PM, Alan Carroll <solidwallofc...@yahoo-inc.com> > wrote: > > Sorry, A, B, and C are config variables, such as > "proxy.config.quick_filter.mask", "proxy.config.quick_filter.mask_in", > "proxy.config.quick_filter.mask_out". > > > On Monday, November 21, 2016 4:15 PM, Sudheer Vinukonda > <sudheervinuko...@yahoo.com.INVALID> wrote: > > > Huh, I'm totally confused..Are "A", "B", "C" different config *settings* or > different *values* for a *given* setting? Your original reply seemed to > indicate (at least, the initial part of the reply) that they were *values* > for a given setting, but, the latest seems to indicate the opposite :-/ > "The use case is providing backwards compatibility. Suppose a plugin uses > config value A. A newer version, in order to support additional features, > uses values B and C. It would be nice to be able to detect that neither B nor > C were explicitly set by the administrator in records.config and therefore > the plugin should fall back and use A. It is also required to *not* fall back > to A if the administrator explicitly set B or C to the default value. > Therefore checking the retrieved value against the default value is > insufficient. One might use a bogus default value then, but now there's a > problem if none of A,B, or C was set." > > > PS: I am only trying to understand the use case or need/benefits of having > this additional new info being proposed - not opposing the need for it! > > > From: Alan Carroll <solidwallofc...@yahoo-inc.com.INVALID> > > To: "dev@trafficserver.apache.org" <dev@trafficserver.apache.org> > Sent: Monday, November 21, 2016 1:55 PM > Subject: Re: Config variable source values > > Let's say the default for B is "Sudheer". There are two cases I want to treat > differently. > 1) No mention of B is in records.config. Fall back to A.2) In records.config, > the value for B is set to "Sudheer" by the administrator. Use this value, do > not look at A. > > > On Monday, November 21, 2016 3:32 PM, Sudheer Vinukonda > <sudheervinuko...@yahoo.com.INVALID> wrote: > > > Hmm..what do you mean by "the administrator explicitly set B or C to the > default value"? > > > > > >
