> -----Original Message----- > From: Parsons, David [mailto:[EMAIL PROTECTED] > Sent: Tuesday, February 03, 2004 8:57 PM > To: '[EMAIL PROTECTED]' > Subject: handling cyclic dependencies > > > We are building a system in which the dependencies among logical > components > may form cycles. I am trying to devise a clean way to build and test this > using maven. The basic idea is to break at least one component from each > cycle into multiple artifacts. E.g. if A depends on B and B > depends on A, I > can break the B component into two projects: one for the interfaces and > object factories (which don't depend on A) and another for the > implementations (which do). Then the build dependencies are: A depends on > B-interface; and B-impl depends on both A and B-interface. > > Using these dependencies, I have succeeded in getting the maven reactor to > build the jars in the correct order, i.e. B-interface; A; B-impl. > In order > to do so, however, I had to suppress the unit tests for component A from > running. This is because they require that the B-impl classes be on the > classpath, which is not described in the dependencies (and cannot > be, since > that would reintroduce a cycle). > > So basically, it seems I need to do a 2-pass build, first to > build the jars > and then to run the tests. The first pass requires that unit testing be > suppressed. The second pass requires that an additional > dependency be added > (or that, in some other way unknown to me, the classpath be > extended during > the JUnit run). How can this be done? > > More generally, is there a standard maven-centric way to deal > with issues of > cyclic dependencies? BTW I am a maven newbie so the usual pleas > apply about > not beating me up if this is already documented somewhere. > > Many thanks in advance - David Parsons >
All "smart books" and "theoretical studies" I know are clarly saying that cyclic dependencies are evil and should be avoided by all means. I haven't yet seen a situation when you reallly need to have them. There is always a clean solution which leads to acyclic graphs of dependencies. Maven just that it helps you to understand desing problems and is refusing to work with cycles. If you have cyclic dependencies that __always__ means that there is something wrong with your modules. Either split them or merge them. Michal --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
