MultiValueKeyMaker not supported with the remote backend

[Olly Betts]

We don't support user subclassed KeyMaker functions, which is a fair bit of work. Adding a special case to support just MultiValueKeyMaker wouldn't be as hard though.

(Son of #384)

[Olly Betts]

Probably suitable for 1.2.x.

[Olly Betts]

More suitable for 1.3 series now, as it would require at least a minor version bump, and I've not seen anyone asking about this.

[Olly Betts]

Still not seen any user requests, so shouldn't block 1.4.0.

[German M. Bravo]

We do use custom KeyMakers; not only MultiValue. In our case, we were thinking about somehow registering key makers and have xapian pass the KeyMaker's registered name to the remote database. The remote database would have to have the same KeyMaker registered to be available.

[German M. Bravo]

How could this be implemented? Particularly I use something like a Multi_MultiValueKeyMaker (which is essentially a multi-typed MultiValueKeyMaker)

[Olly Betts]

Hmm, did I answer this on IRC before or something? Sorry if I just failed to respond at all previously.

For the general case, it ought to follow the pattern of MatchSpy, PostingSource, etc with serialise(), unserialise(), clone() and name() virtual methods which subclasses implement, and registering with a Registry object on the remote side.

Updating milestone - this is probably not 1.4.x material at this point in the release cycle.

[Olly Betts]

Working on a patch (to support user subclasses, not just MultiValueKeyMaker).

[Olly Betts]

Fixed in git master by 53fbb5dd8441e141858bed81750daab9f82e9cef. This requires incompatible remote protocol changes, so can't easily be backported to 1.4.x.