PoC in Node

Cargo.lock

@@ -2144,7 +2144,6 @@ name = "derive"
 version = "0.1.0"
 dependencies = [
  "proc-macro2",
- "pyo3",
  "quote",
  "quote_into",
  "syn 1.0.109",
@@ -2457,6 +2456,7 @@ name = "dora-node-api-python"
 version = "0.3.4"
 dependencies = [
  "arrow",
+ "derive",
  "dora-node-api",
  "dora-operator-api-python",
  "dora-ros2-bridge-python",

Cargo.toml

@@ -67,6 +67,7 @@ dora-coordinator = { version = "0.3.4", path = "binaries/coordinator" }
 dora-ros2-bridge = { path = "libraries/extensions/ros2-bridge" }
 dora-ros2-bridge-msg-gen = { path = "libraries/extensions/ros2-bridge/msg-gen" }
 dora-ros2-bridge-python = { path = "libraries/extensions/ros2-bridge/python" }
+derive = { path = "derive" }
 arrow = { version = "52" }
 arrow-schema = { version = "52" }
 arrow-data = { version = "52" }

apis/python/node/Cargo.toml

@@ -25,6 +25,7 @@ arrow = { workspace = true, features = ["pyarrow"] }
 pythonize = { workspace = true }
 futures = "0.3.28"
 dora-ros2-bridge-python = { workspace = true }
+derive = { workspace = true }
 
 [lib]
 name = "dora"

apis/python/node/src/lib.rs

@@ -24,6 +24,7 @@ use pyo3::types::{PyBytes, PyDict};
 /// ```
 ///
 #[pyclass]
+#[derive(derive::DirHelper)]
 pub struct Node {
     events: Events,
     node: DoraNode,
@@ -197,6 +198,13 @@ impl Node {
 
         Ok(())
     }
+
+    // TODO: We should only list fields which are at least readableby Python users, right?
+    
+    /// Get a list of the fields of this Node. 
+    pub fn __dir__(&self) -> Vec<String> {
+        self.fields()
+    }
 }
 
 enum Events {

derive/Cargo.toml

@@ -8,7 +8,6 @@ syn = "1.0"
 quote = "1.0"
 proc-macro2 = "1.0"
 quote_into = "0.2.0"
-pyo3 = { workspace = true, features = ["eyre", "abi3-py37"] }
 
 [lib]
 proc-macro = true

derive/src/lib.rs

@@ -1,9 +1,15 @@
+//! Derive macros for dora
+
 extern crate proc_macro;
 use proc_macro::TokenStream;
 use quote::quote;
 use syn::{parse_macro_input, Data, DeriveInput, Fields};
 
-/// Add a Python `__dir__`` method to the struct.
+/// Add a `fields` method to the struct.
+/// 
+/// Because we cannot have multiple `#[pymethods]` impls, this macro
+/// produces a function called `fields` which should be called from the
+/// PyO3 impl.
 #[proc_macro_derive(DirHelper)]
 pub fn dir_helper_derive(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
@@ -31,9 +37,8 @@ pub fn dir_helper_derive(input: TokenStream) -> TokenStream {
                         }
                     }];);
                     quote! {
-                        #[pyo3::prelude::pymethods]
                         impl #name {
-                            pub fn __dir__(&self) -> Vec<String> {
+                            pub fn fields(&self) -> Vec<String> {
                                 let mut names = Vec::new();
                                 #assigner
                                 names
@@ -44,9 +49,8 @@ pub fn dir_helper_derive(input: TokenStream) -> TokenStream {
                 Fields::Unit => {
                     // If the struct has no fields
                     quote! {
-                        #[pyo3::prelude::pymethods]
                         impl #name {
-                            pub fn __dir__(&self) -> Vec<String> {
+                            pub fn fields(&self) -> Vec<String> {
                                 Vec::new()
                             }
                         }

derive/tests/functional.rs

@@ -1,8 +1,6 @@
 use derive::DirHelper;
-use pyo3::pyclass;
 
 #[derive(DirHelper)]
-#[pyclass]
 #[allow(dead_code)]
 struct WithFields {
     hello: (),
@@ -19,7 +17,7 @@ fn test_with_fields() {
         my: "".to_string(),
         name: 0.0,
     }
-    .__dir__();
+    .fields();
     assert_eq!(
         vec![
             "hello".to_string(),
@@ -32,12 +30,11 @@ fn test_with_fields() {
 }
 
 #[derive(DirHelper)]
-#[pyclass]
 #[allow(dead_code)]
 struct UnitNoFields;
 
 #[test]
 fn test_no_fields() {
-    let fields: Vec<String> = UnitNoFields.__dir__();
+    let fields: Vec<String> = UnitNoFields.fields();
     assert_eq!(Vec::<String>::new(), fields);
 }