Handling runtime tree modifications

[agrover]

Object paths supported by a tree may come and go. Tree has an add() but lacks remove(). It's easy to add a remove() that just removes it from self.paths, but it looks like we also need to call c.unregister_object_path...but only if after set_registered() has been called. So basically I'm thinking to enable adding/removing object paths at runtime we need to either pass c to add() & remove() and register/unregister within those functions, but then we don't really need set_registered() any more? But then maybe we want to unregister any remaining paths from Drop?

Wanted to get your thoughts on what it would take to properly enable this.

[agrover]

Or maybe, moving the Connection from TreeServer to Tree might be the right thing to do? A bigger change, though.

[diwic]

A basic workaround for this is to add and remove trees rather than paths in the tree. You can have one tree for every path, if you like.

[diwic]

Or maybe, moving the Connection from TreeServer to Tree might be the right thing to do? A bigger change, though.

No, that'll break some use case someone else had, which was "send message to tree in another thread, do lengthy processing without blocking main thread, send result over to main thread and send reply"

A basic workaround for this is to add and remove trees rather than paths in the tree. You can have one tree for every path, if you like.

On second thought, this will only work for paths that are not children of paths in another tree, because that'll break introspection, GetManagedObjects etc, because they won't find its children if they are in another tree.

[diwic]

The idea of having a tree.remove() function that allows you to modify your object path and then put it back in is appealing. Perhaps tree.add() and tree.remove() could take an additional Option<&Connection> that would optionally auto-register/unregister? (Or have tree.add_and_register() / tree.remove_and_unregister() functions.)

[diwic]

This won't fix sending out org.freedesktop.DBus.ObjectManager.InterfacesAdded if you remove an object path, add an interface to it, and then put it back in, but perhaps that's a separate problem we can think of some other time.

[diwic]

Fixed in v0.3.3 (at least removing object paths from a tree - maybe want to remove interfaces from object paths, methods from interfaces etc etc in the future)