Update properties whihout setter

[gnulux]

Hi ,

I'm testing this code in order to update a readonly property from service. But my offset property does not seam to update as expected.
Can you help ?

use tokio::{task, time::Duration};
use zbus::names::InterfaceName;
use zbus::{connection, interface, SignalContext};
use zbus::fdo::PropertiesProxy;
use zbus::{Connection, Result, zvariant};
use zvariant::{OwnedValue};



#[derive(Clone)] 
struct Greeter {
    offset: i32,
}


#[interface(name = "org.example.TestInterface")]
impl Greeter {
 
    /// A "GreeterName" property.
    #[zbus(property)]
    async fn offset(&self) -> i32 {
        self.offset
    }
    
    //#[zbus(property)]
    async fn  set_offset(&mut self, o: i32) {
        self.offset = o;
        println!("Update offset is called with value : {o}");
    }

}


#[tokio::main]
async fn main() -> Result<(),> {

    let mut greeter = Greeter {
        offset: 23
    };

    let _conn = connection::Builder::session()?
        .name("org.example.TestServer")?
        .serve_at("/org/example/TestServer", greeter.clone())?
        .build()
        .await?;
  
    let connect = Connection::session().await?;

    tokio::time::sleep(Duration::from_secs(4)).await;
   
    let path = zbus::zvariant::ObjectPath::try_from("/org/example/TestServer")?;

    connect
    .object_server()
    .at(path.clone(), greeter)
    .await?;
    
    let iface_ref = connect
        .object_server()
        .interface::<_, Greeter>(path).await?;

    let mut iface = iface_ref.get_mut().await;

    iface.offset = 120;
    let _ = iface.offset_changed(iface_ref.signal_context()).await;

    let _ = task::spawn(async move {
        let mut v:i32 = 0;

        loop {

            println!("offset = {v}");
            
            tokio::time::sleep(Duration::from_secs(2)).await;
            v+=1;
        }

    }).await;


    Ok(())
}

[zeenix]

    let mut iface = iface_ref.get_mut().await;

This is probably your issue: You shouldn't keep mutable reference to the interface around, as documented in the method docs:

WARNINGS: Since the ObjectServer will not be able to access the interface in question until the return value of this method is dropped, it is highly recommended that the scope of the interface returned is restricted.

Also:

• You're needlessly creating 2 connections and 2 instances of your interface. Looking at your code, it doesn't seem like that's what you want.
• If you are only going to await on it, you probably also don't want to spawn a task. You can directly do:

    async move {
        let mut v:i32 = 0;

        loop {

            println!("offset = {v}");
            
            tokio::time::sleep(Duration::from_secs(2)).await;
            v+=1;
        }

    }.await;

[gnulux]

Hi zeenix,

you were right the scope was the issue it works now . a big thank to you

use tokio::{task, time::Duration};
use zbus::names::InterfaceName;
use zbus::{connection, interface, SignalContext};
use zbus::fdo::PropertiesProxy;
use zbus::{Connection, Result, zvariant};
use zvariant::{OwnedValue};



#[derive(Clone)] 
struct Greeter {
    offset: i32,
}


#[interface(name = "org.example.TestInterface")]
impl Greeter {
 
    /// A "GreeterName" property.
    #[zbus(property)]
    async fn offset(&self) -> i32 {
        self.offset
    }
    
    //#[zbus(property)]
    async fn  set_offset(&mut self, o: i32) {
        self.offset = o;
        println!("Update offset is called with value : {o}");
    }

}


#[tokio::main]
async fn main() -> Result<(),> {

    let mut greeter = Greeter {
        offset: 23
    };

    // let mut g = greeter.clone();

    let _conn = connection::Builder::session()?
        .name("org.example.TestServer")?
        .serve_at("/org/example/TestServer", greeter.clone())?
        .build()
        .await?;
 
    let path = zbus::zvariant::ObjectPath::try_from("/org/example/TestServer")?;

    _conn
    .object_server()
    .at(path.clone(), greeter)
    .await?;
    
    let iface_ref = _conn
        .object_server()
        .interface::<_, Greeter>(path).await?;

    async move {
        let mut v:i32 = 0;

        loop {

            println!("offset = {v}");
            {
                let mut iface = iface_ref.get_mut().await;
                iface.offset= v;
                let _= iface.offset_changed(iface_ref.signal_context()).await;
            }
            tokio::time::sleep(Duration::from_secs(2)).await;
            v+=1;
        }

    }.await;


    Ok(())
}