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Author: grtlr

crates/top/re_sdk/src/lenses.rs

@@ -121,6 +121,7 @@ mod op {
     use super::Error;
 
     /// Extracts a specific field from a struct component within a `ListArray`.
+    #[derive(Debug)]
     pub struct AccessField {
         pub(super) field_name: String,
     }
@@ -157,6 +158,7 @@ mod op {
     }
 
     /// Casts the `value_type` (inner array) of a `ListArray` to a different data type.
+    #[derive(Debug)]
     pub struct Cast {
         pub(super) to_inner_type: DataType,
     }
@@ -215,6 +217,16 @@ pub enum Op {
     Func(Box<dyn Fn(ListArray) -> Result<ListArray, Error> + Sync + Send>),
 }
 
+impl std::fmt::Debug for Op {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Op::AccessField(access_field) => f.debug_tuple("AccessField").field(field).finish(),
+            Op::Cast(cast) => f.debug_tuple("Cast").field(cast).finish(),
+            Op::Func(_) => f.debug_tuple("Func").field(&"<function>").finish(),
+        }
+    }
+}
+
 impl Op {
     /// Extracts a specific field from a `StructArray`.
     pub fn access_field(field_name: impl Into<String>) -> Self {
@@ -378,12 +390,19 @@ impl Lens {
 
             let mut list_array_result = list_array.clone();
             for op in &output.ops {
-                if let Ok(result) = op.call(list_array_result) {
-                    list_array_result = result;
-                } else {
-                    // TODO: context!
-                    re_log::error!("failed");
-                    return vec![];
+                match op.call(list_array_result) {
+                    Ok(result) => {
+                        list_array_result = result;
+                    }
+                    Err(err) => {
+                        re_log::error!(
+                            "Lens operation '{:?}' failed for output column '{}' on entity '{}': {err}",
+                            op,
+                            output.entity_path,
+                            output.component_descr.component
+                        );
+                        return vec![];
+                    }
                 }
             }
 

examples/rust/lenses/README.md

@@ -1,10 +1,8 @@
 <!--[metadata]
-title = "Transform recording stream example"
+title = "Lenses example"
 -->
 
-<!-- TODO: -->
-
-Demonstrates how to transform log messages before forwarding them to the sink the SDK.
+Demonstrates how to use lenses to transform log messages before forwarding them to an underlying sink.
 ```bash
 cargo run -p lenses
 ```