Rust::com Field APIs design and example of usage by bharatGoswami8 · Pull Request #700 · eclipse-score/communication

bharatGoswami8 · 2026-07-14T05:41:49Z

edit -

Since the Field and Method changes are closely related, and the Field implementation also uses the Method interface while both share the same macro for the interface and type-state pattern, I believe it would be better to review the overall design in a single PR. This will help ensure that any suggestions or feedback can be addressed more effectively and consistently across both implementations.
Therefore, I am closing this PR. Please review the PR - #818

Added field-based publish/subscribe with field get/set and asynchronous field subscriptions.
Extended interface macros to support field members and generated producer/consumer and compile-time offer API enable.
Added a new example demonstrating offered field producers and consumer field updates.

#579

darkwisebear

I mainly reviewed the concept part; I think we need to nail that part before it makes sense to look at the rest.

darkwisebear · 2026-07-27T08:41:37Z

+    // Must register handlers and initialize all fields before offer() is available
+    let offered = producer
+        .init_field()
+        .register_set_handler_left_tire(move |val: &Tire| {


I wonder whether &Tire is correct. Why not hand over ownership to the callable? This way, the implementer wouldn't have to clone the value in the likely case the value is written somewhere.

Updated callable with Fn(T)

darkwisebear · 2026-07-27T08:43:52Z

+            println!("Received exhaust update");
+        })
+        .expect("Failed to register set handlers")
+        .update_left_tire(&initial_tire_value)


Why by-reference? This forces cloning as the implementation most likely has to clone the value to send it across the network. It might be a corner case, though.

Agreed, i was trying to match with C++ semantic but this will add additional clone, will go with same approach of send for Event.

darkwisebear · 2026-07-27T08:47:35Z

+use std::fmt::Debug;
+use std::future::Future;
+
+#[allow(dead_code)]


Why is this dead code?

Updated example app.

darkwisebear · 2026-07-27T09:15:36Z

+#[allow(dead_code)]
+// Temp for build test
+// We will remove this once memory layout of same created in rust side like SamplePtr.
+#[repr(C)]


Doesn't this trigger an "improper_ctypes" lint? Result isn't #[repr(C)], so it cannot be used here properly.

This is temporary placeholder of MethodReturnTypePtr of C++ like SamplePtr for Event.

Now we are using method interface to create Field's method (set and get), so this is removed.

darkwisebear · 2026-07-27T09:21:50Z

+// or by default we will enable for user,
+// -> we can keep it default enable as of now,
+// and later we can add tag based mechanism if required because Interface side we need to check how we can do this
+// 2. We are offering get method after subscrption async but before subscription it is sync,


Just turn the one before subscription into async. Or is there anything that prevents you from doing so?

Now we are using method interface to create Field's method (set and get), so this is removed but
We have another issue consumer partially moved when we call subscribe on field because it take self by value.

darkwisebear · 2026-07-27T09:24:17Z

+// we will create a module which will have common trait for event and field which will be used by both event and field as a super trait and
+// for this we need to create marker trait for event.
+
+use crate::*;


Please import specific types. Yes, it's tedious, but being explicit here also saves some headaches.

darkwisebear · 2026-07-27T09:33:59Z

+    /// # Returns
+    /// Return the result of `Result<()>` which contains the status of the register operation.
+    // TODO: Do we need to make callback lifetime 'static or we keep same as field publisher lifetime.
+    fn register_set_handler<'a>(&self, callback: impl Fn(&T) + Send + 'a) -> Result<()>;


There is no equivalent method for registering the get handler. It may sound weird, but the C++ counterpart has that, since mw::com treats set and get as ordinary methods.

darkwisebear · 2026-07-27T09:34:59Z

+    /// # Returns
+    /// Return the result of `Result<()>` which contains the status of the register operation.
+    // TODO: Do we need to make callback lifetime 'static or we keep same as field publisher lifetime.
+    fn register_set_handler<'a>(&self, callback: impl Fn(&T) + Send + 'a) -> Result<()>;


TO me this feels as if we're treating ordinary methods and field methods in a distinct way. Maybe we should think about getting methods ready first and then incorporate them as the foundation of set and get here.

Method Design is ready - #777
Working on Combined Field and Method changes.

darkwisebear · 2026-07-27T09:36:08Z

@@ -329,18 +342,10 @@ where
 ///
 /// # Type Parameters
 /// * `T` - The relocatable event data type
-pub trait SampleMut<T>: DerefMut<Target = T> + Debug
+pub trait EventSampleMut<T>: SampleMut<T>


Is this just because of update vs send (aka naming)?

Yes, because of that SampleMut is just marker trait and then we have feature specific trait which provide the API like send and update.

* Created field interface APIs * Updated SampleMut to use in field as well

* Lola Runtime placeholder implementaion for field producer and consumer * Mock Runtime placeholder implementation

* Create proc macro for field init and set handler validation before offer call

* Updated example file with Field APIs usage

* Method and field both code generation added on macros

bharatGoswami8 · 2026-07-30T11:25:24Z

@darkwisebear , I will create a separate PR based on the Method Design PR, and all review feedback will be addressed in that PR.

bharatGoswami8 · 2026-07-31T09:42:52Z

Hi @darkwisebear , @rpreddyhv ,

I have created PR #818 for field design based on Method design interface.

I already addressed most of the review comment on this PR.

Request for review mentioned PR.

Closing this PR.

bharatGoswami8 requested review from LittleHuba, bemerybmw, castler, crimson11, hoe-jo and limdor as code owners July 14, 2026 05:41

github-project-automation Bot added this to COM - Communication FT Jul 14, 2026

github-project-automation Bot moved this to Backlog in COM - Communication FT Jul 14, 2026

bharatGoswami8 self-assigned this Jul 14, 2026

bharatGoswami8 requested review from darkwisebear and pawelrutkaq July 14, 2026 05:42

bharatGoswami8 force-pushed the Rust_Field_APIs_Desing_and_Example branch 2 times, most recently from 70fbb6e to f7cd859 Compare July 14, 2026 05:45

bharatGoswami8 commented Jul 14, 2026

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Comment thread score/mw/com/rust/score_com_concept/interface_macros.rs Outdated

bharatGoswami8 force-pushed the Rust_Field_APIs_Desing_and_Example branch 3 times, most recently from 6faaa6c to 21d958d Compare July 14, 2026 06:23

bharatGoswami8 added the rust-api label Jul 14, 2026

bharatGoswami8 force-pushed the Rust_Field_APIs_Desing_and_Example branch from 30e0af1 to 8589c65 Compare July 19, 2026 08:53

anmittag moved this from Backlog to In Progress in COM - Communication FT Jul 21, 2026

rpreddyhv reviewed Jul 24, 2026

View reviewed changes

Comment thread score/mw/com/example/com-api-example/basic-consumer-producer.rs Outdated

Comment thread score/mw/com/example/com-api-example/basic-consumer-producer.rs Outdated

Comment thread score/mw/com/example/com-api-example/basic-consumer-producer.rs Outdated

darkwisebear suggested changes Jul 27, 2026

View reviewed changes

bharatGoswami8 added 4 commits July 29, 2026 11:36

Rust::com Create the Field APIs

058e74f

* Created field interface APIs * Updated SampleMut to use in field as well

Rust::com Runtime placeholder Implementation for Field

f971a9a

* Lola Runtime placeholder implementaion for field producer and consumer * Mock Runtime placeholder implementation

Rust::com Create type state macro for field Init

14f8257

* Create proc macro for field init and set handler validation before offer call

Rust::com Update the example app with Field APIs usage

3d76ef9

* Updated example file with Field APIs usage

bharatGoswami8 force-pushed the Rust_Field_APIs_Desing_and_Example branch from 8589c65 to 3d76ef9 Compare July 29, 2026 08:31

Rust::com Interface and type state macro optimization

8e26653

* Method and field both code generation added on macros

bharatGoswami8 closed this Jul 31, 2026

github-project-automation Bot moved this from In Progress to Done in COM - Communication FT Jul 31, 2026

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bharatGoswami8 commented Jul 30, 2026

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bharatGoswami8 commented Jul 14, 2026 •

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