Keep type definitions in lockstep with DBus XML descriptions, with zbus.
This provides means to match the signature of <T as zvariant::Type>::signature() with a corresponding signature from a DBus XML file.
zbus-lockstep prevents definitions from drifting apart by offering means to retrieve and assert that the signature of a type
corresponds to signature in the currently valid XML.
To ensure that a type's implementation matches a signature in an external XML DBus description.
In the context of IPC over DBus - especially where are multiple implementations of servers and/or clients - it is necessary for each implementation to match what others expect.
The XML descriptions may act as a shared overarching frame of reference or "single source of all truth". Having a single point of reference helps all implementers meet expectations on protocol conformance.
Add zbus-lockstep to Cargo.toml's dev-dependencies:
toml
[dev-dependencies]
zbus-lockstep = "0.1.0"
Consider the followwing XML description,
an interface with a single, simple signal in the Cache.xml file:
```XML
<signal name="RemoveNode">
<arg name="nodeRemoved" type="(so)"/>
</signal>
```
The type in our implementation might look like this:
```rust
struct Node { name: String, path: OwnedObjectPath, } ```
The derive macro in this example implements the zvariant::Type.
This means we can now call <Node as Type::signature(), which will return a zvariant::Signature of the type.
The test below shows how zbus-lockstep may be used given what we know about the type.
```rust use zbus_lockstep;
#[test]
fn test_get_signature_of_cache_remove_accessible() {
let xml = PathBuf::from("xml/Node.xml");
let iface = "org.example.Node";
let member = "RemoveNode";
let signature = get_signal_body_type(xml, iface, member, None).unwrap();
assert_eq!(signature, Node::signature());
}
```
Obviously, the user here needs to take care to ensure that the XML descriptions that are in use,
are indeed currently valid and the most recent available.
```rust
pub struct ActivateEvent { event: String, serial: u32, // } ```
Caveat: Requires a sub-crate.
This crate started out as a fork from Tait Hoyem's zbus-xml-match.
MIT