Can somebody explain @ObjectDependencies to me?

[bschmalhofer]

Apparently I can't wrap my head around @ObjectDependencies. My understanding is that the dependencies declaration is used in Kernel::System::ObjectsDiscard() for making sure that the modules that depend on the to be discarded module are discarded first. That makes sense. But let's take a look at a concrete example. Kernel::GenericInterface::Providerdeclares that it depends on Kernel::GenericInterface::Errorhandling. So when K::G::E is discarded, than K::G::P is discarded too. But why should K::G::P care when K::G::E has been discarded? Whenever K::G::P needs a K::G::E, it gets the singleton that has been constructed with the current object params. I see no need to discard K::G::P. It would be a different when the state of K::G::P would depend on K::G::E, e.g. when K::G::E were used in the constructor of K::G::P for setting attributes.

[svenoe]

Mostly as I understand it, it is, that objects are discarded at all. Just deleting $Self->{Objects}{K::G::P} in the OM wouldn't have any effect on $Self->{Objects}{K::G::E}. The order is important only in special cases, have a look at Kernel/System/Web/InterfaceAgent.pm e.g., where sub DESTROY would instantiate a new Kernel::System::Log, which for that reason has to be deleted after K::S::W::I. (Ok, it's a bad example, as the K::S::W::I isn't managed by the OM atm, and also, if it is gone, the whole session will likely be gone, but just for the principle.)

[bschmalhofer]

Still confused. Objects being recreated in DESTROY is an issue. But that is a fairly special case. It would not warrant that every object that is used somewhere be declared as a dependency.

As I see it this leaves us with two reasons for declaring a dependency:

• The state of an object depends on the previous state of another object.
• The DESTROY() method depends on another object.

I'm not sure about the latter point, as object recreation should be fine. The point being, that the constructor uses the new params.

[svenoe]

Taking everything back - I didn't properly read it. It is the state you mentioned, as we discussed. E.g. $Self->{ConfigObject} in Kernel/System/User/Preferences/DB.pm.

[bschmalhofer]

I now have a better idea of the use of the object dependencies. So, I propose to adapt the code policy, See https://github.com/RotherOSS/CodePolicy/issues/63. Closing this discussion.

[bschmalhofer]

This is the answer. Can I mark it as such?

[bschmalhofer]

Answer was found.