NOTES_ON_PORT.md

Notes on porting to zbus

Plan: start a section of code that will be easy convert to zbus, while keeping dbus dependency. I think that this would be Item, which is a "leaf" struct (meaning it doesn't create other dbus-connected structs). This way I only have to worry about any data being received, and not so much data being returned.

Plan, revised: I should still start with Item. However, the place where I'll slide zbus in is a little different then I had thought. This is because my code currently is structured:

• With an Interface (which should actually be called a proxy that talks to the interface) that is a very low-level implementation of basics like method calls.
• And then all the details of talking to the service interface are handled directly in Item's methods.

With zbus, I would instead have:

• A derived dbus_proxy, which would set up all the boilerplate for talking to a an interface, and then
• Methods in Item would generally just be calling the derived dbus_proxy.
• This means that with zbus, I should be able to get rid of Interface.

So, my first step should be to replace usage of the Item proxy.

First Pass

Creating proxy was nice, and removed a lot of my boilerplate.

One issue was lifetimes for using a path in creating a new proxy. I had wanted to store the proxy in the Item struct, but I needed to borrow the item_path, which wouldn't live long enough. I ended up instantiating a new proxy on each Item method, which didn't feel as good.

Now, getting some test errors. One is that session doesn't exist.

Second Pass

First finished creating all the proxies.

I found Proxy::new_for_owned which removed the instantiation of a proxy per-method, now the Proxy can be saved in the struct.

There's a weird issue where on a derived property it allows ObjectPath in the return, but on methods it requires OwnedObjectPath. Seems to work ok, oh well.

Looks like SecretStruct needs to be wrapped in another struct in order to fit the dbus signature, not sure what that's about.

Otherwise pretty straightforward. Removing the low-level details of creating dbus types allowed me to refactor much more easily.