Something doesn't have to be in Java to be universal (as SLF4J really is), and conversely, something being in Java doesn't make the world instantly catch up (eg YodaTime vs J8+).
Adding the nop logger as a dep seems like the wrong thing to do and will (IIRC) cause a warning/error at runtime if there's another one present. Leaving it out (IIRC) falls back to that anyway with a warning given. IE, I don't think adding that does any good whatsoever. IIRCs because it's been a long time since I had this misconfigured :-) On Tue, Aug 16, 2016 at 4:47 AM, Christopher <ctubb...@apache.org> wrote: > On Mon, Aug 15, 2016 at 2:37 AM Michael Osipov <micha...@apache.org> > wrote: > > > Am 2016-08-14 um 23:21 schrieb Christopher: > > > On Sun, Aug 14, 2016 at 4:31 PM Michael Osipov <micha...@apache.org> > > wrote: > > > > > >> Am 2016-08-12 um 23:48 schrieb Christopher: > > >>> Hi, > > >>> > > >>> I use a plugin which has a runtime dependency on an slf4j > > implementation, > > >>> but the plugin itself is built without declaring one in its pom. ( > > >>> https://github.com/koraktor/mavanagaiata/issues/43) > > >>> > > >>> In some versions of Maven, I get a warning about slf4j not finding an > > >>> implementation. In other versions, it is silent. > > >>> > > >>> Was an slf4j implementation provided in newer versions to the > execution > > >> of > > >>> plugins? > > >>> > > >>> Will there be a multiple-binding conflict if the plugin itself > provides > > >> one > > >>> of its own to get rid of the warning on certain versions of maven > which > > >>> result in that warning (I didn't see one when I tried)? > > >>> > > >>> If there is a risk of a conflict, which implementation would be > > preferred > > >>> in order to converge on one provided by Maven? > > >>> > > >>> Is there another solution the plugin should seek? > > >>> > > >>> In general, what dependencies are plugins expected to provide, and > what > > >>> dependencies are expected to be provided by Maven, and how are > > conflicts > > >>> resolved in the architecture? > > >>> > > >>> Feel free to comment on the GitHub issue directly, or here. I'll be > > >>> watching both. > > >> > > >> I will cite what I have written on Stack Overflow > > >> (http://stackoverflow.com/a/7107934/696632) five years ago and it > still > > >> holds true: > > >> > > >> You *never* provide a log implementation. The client application has > to > > >> do so. Otherwhise this would be a violation of separation of concerns. > > >> Don't do any assumptions about an unknown client. > > >> > > >> > > > I agree with that sentiment...generally. But this is a maven plugin, so > > I'm > > > trying to figure out what Maven is going to provide it when it > executes. > > If > > > it's not going to provide an implementation, then the plugin has to. If > > you > > > have answers to the specific questions I asked above, I think it might > > help. > > > > It should not matter to you what Maven provides. It will always provide > > some backend. Otherwise Maven won't be able to log itself. Even if > > Maven would not provide anything. It is not your task to force some > > implementation. It is a several failure of the client to do so. > > > > Michael > > > > That would make more sense to me if there were a universally agreed upon > logging API, and all clients were guaranteed to provide *some* backend for > that standard logging API. Unfortunately, no logging API seems to be > universal, and the one provided in Java itself is awful. I'm not even sure > what Maven uses underneath, and it may not use SLF4J at all (which means it > has no reason to provide an implementation). > > This is actually a pretty unfortunate circumstance in the first place... > Maven plugins should only be logging to the provided Maven logger itself, > and the plugin shouldn't care what backend Maven is using for that logger. > This > particular plugin is doing the right thing... using the Maven logger and > relying on Maven for the backend. Unfortunately, it seems the > org.eclipse.jgit dependency does its own logging, and that's outside this > plugin's control. > > Until there is a universal logging framework, these heuristics about what > the "right" thing to do are not going to be perfect. Ideals like "rely on > the client to provide the implementation" aren't going to fully match > reality. Personally, I'd like to see an slf4j-like API make its way into > Java itself. Then, perhaps these kinds of issues wouldn't come up as often. >
