[snip] > > > > > >> > Hi devs, > > > > > >> > > > > > > >> > Right now our strategy is for script services and script APIs in > > > > > >> > general > > > > > >> > to catch exceptions, store them and offer a getLastError() > > > > > >> > method to get > > > > > >> > them (see > > > > > >> > http://extensions.xwiki.org/xwiki/bin/view/Extension/Script+Module#HBestPractices > > > > > >> > ) > > > > > >> > > > > > > >> > However it would be much nicer to: > > > > > >> > * Let our script services generate exceptions > > > > > >> > * Offer a velocity script service to get the last exception > > > > > >> > raised by a > > > > > >> > java call from velocity > > > > > >> > * Implement this uberspector to catch the exceptions and to set > > > > > >> > them in > > > > > >> > the execution context > > > > > >> > > > > > > >> > That should be quite easy to implement IMO. > > > > > >> > > > > > > >> > WDYT? > > > > > >> > > > > > > >> > > > > > >> +1, it's a pain to call setLastError() everywhere there can be an > > > > > >> exception > > > > > >> thrown, and we almost always forget to do it (for this reason). > > > > > >> > > > > > >> Note that we also have the #try() directive now. > > > > > > > > > > > > Yes, I should have mentioned that there’s indeed also this > > > > > > possibility: > > > > > > * Have script API throw Exceptions > > > > > > * Force velocity script users to wrap their code with the try > > > > > > directive when they need to catch exceptions > > > > > > > > > > > > I still believe that the use of the Exception-catching uberspector > > > > > > is better. > > > > > > > > > > > > WDYT? > > > > > > > > > > Does it mean you plan to get rid of new #try directive ? Because it > > > > > will be broken with this new uberspector. > > > > > > > > That’s a good point, I had not thought about the implementation at this > > > > stage. > > > > > > > > I think this could still work. When the #try directive is used I’d just > > > > have to setup some flag somewhere in Velocity and in the uberspector I > > > > could check if this flag is set and if so then don’t catch the > > > > exception. > > > > > > > > > Actually, thinking more, I think you’re right and that the #try directive > > > plays exactly the same role as an Exception-catching uberspector and I > > > don’t see the need for the #try directive if we provide an uberspector. > > > > > > So I’m proposing to deprecate it but still keep it for backward > > > compatibility for now (probably a full cycle). > > > > > > WDYT? > > > > Note that I’d like to change a bit the proposal and instead of making the > > exception available from a script service, I’d prefer to make it available > > as a known velocity binding such as $lastException. There’s no reason to > > use a script service since that would mean it would work for all scripts > > and in this case we only want it to work for Velocity. > > > > Since there’s no way to get the Velocity Context from within an > > uberspector, I’ll get it by using our Component Manager and get the > > VelocityManager component and call getVelocityContext()… If you know a > > better way, let me know. > > hmm… this would mean that I’d need to put this new uberspector in > xwiki-platform since VelocityManager is in platform ATM… (@Thomas: our > discussion of yesterday ;)).
There’s an alternative, which is to modify our implementation of VelocityEngine.evaluate() and decorate the source with a #try() directive so that it’s always called (and make sure that calling it nested won’t affect it for backward compat). This could be simpler to implement and doesn’t force us to move some velocity code to platform. WDYT? Thanks -Vincent [snip] _______________________________________________ devs mailing list devs@xwiki.org http://lists.xwiki.org/mailman/listinfo/devs
