Merge pull request #6 from rjaduthie/add_traceback

Add clear backtrace on PyO3 error during main.py initialisation

Author: marcomq

src/error.rs

@@ -4,7 +4,7 @@
 //  git clone https://github.com/marcomq/tauri-plugin-python
 
 #[cfg(feature = "pyo3")]
-use pyo3::PyErr;
+use pyo3::{prelude::*, PyErr};
 use serde::{ser::Serializer, Serialize};
 
 pub type Result<T> = std::result::Result<T, Error>;
@@ -63,9 +63,95 @@ impl From<rustpython_vm::PyRef<rustpython_vm::builtins::PyBaseException>> for Er
 #[cfg(feature = "pyo3")]
 impl From<PyErr> for Error {
     fn from(error: PyErr) -> Self {
-        let msg = error.to_string();
-        println!("error: {}", &msg);
-        Error::String(msg)
+        let error_msg = match pyo3::Python::with_gil(|py| -> Result<Vec<String>> {
+            let traceback_module = py.import("traceback")?;
+            let traceback_object = error
+                .traceback(py)
+                .ok_or(pyo3::exceptions::PyWarning::new_err("No traceback found."))?;
+            let extract_traceback = traceback_module.getattr("extract_tb")?;
+
+            // Get the formatted traceback lines
+            let result = extract_traceback.call1((traceback_object,)).and_then(|r| {
+                match r.extract::<Vec<PyObject>>() {
+                    Ok(v) => {
+                        let mut formatted_lines = Vec::new();
+                        for arg in v.iter() {
+                            let frame = arg.bind(py);
+
+                            // Extract filename
+                            let filename = match frame.getattr("filename") {
+                                Ok(f) => match f.extract::<String>() {
+                                    Ok(s) if s == "<string>".to_string() => {
+                                        // Special handling for <string>
+                                        frame.setattr("filename", "main.py")?;
+                                        let lineno = frame.getattr("lineno")?.extract::<usize>()?;
+                                        frame.setattr("lineno", lineno - 2)?;
+                                        "main.py".to_string()
+                                    }
+                                    Ok(s) => s,
+                                    Err(_) => "<unknown>".to_string(),
+                                },
+                                Err(_) => "<unknown>".to_string(),
+                            };
+
+                            // Extract line number
+                            let lineno = match frame.getattr("lineno") {
+                                Ok(l) => match l.extract::<usize>() {
+                                    Ok(n) => n,
+                                    Err(_) => 0,
+                                },
+                                Err(_) => 0,
+                            };
+
+                            // Extract function name
+                            let name = match frame.getattr("name") {
+                                Ok(n) => match n.extract::<String>() {
+                                    Ok(s) => s,
+                                    Err(_) => "<unknown>".to_string(),
+                                },
+                                Err(_) => "<unknown>".to_string(),
+                            };
+
+                            // Extract line content (if available)
+                            let line = match frame.getattr("line") {
+                                Ok(l) => match l.extract::<Option<String>>() {
+                                    Ok(Some(s)) => format!("\t{}", s),
+                                    _ => "".to_string(),
+                                },
+                                Err(_) => "".to_string(),
+                            };
+
+                            // Format the line like requested
+                            let formatted_line = format!(
+                                "File \"{}\", line {}, in {}\n{}",
+                                filename, lineno, name, line
+                            );
+
+                            formatted_lines.push(formatted_line);
+                        }
+
+                        Ok(formatted_lines)
+                    }
+                    Err(_) => Err(PyErr::new::<pyo3::exceptions::PyValueError, _>(
+                        "Failed to extract traceback",
+                    )),
+                }
+            })?;
+
+            // Add traceback header
+            let mut full_traceback = vec!["Traceback (most recent call last):".to_string()];
+            full_traceback.extend(result);
+
+            // Add error type and message
+            full_traceback.push(error.to_string());
+
+            Ok(full_traceback)
+        }) {
+            Ok(formatted) => formatted.join("\n"),
+            Err(_) => error.to_string(), // Fall back to simple error message
+        };
+
+        Error::String(error_msg)
     }
 }
 

src/lib.rs

@@ -107,7 +107,7 @@ sys.path = sys.path + [{}]
         code
     );
     py_lib::run_python_internal(path_import, "main.py".into())
-        .unwrap_or_else(|e| panic!("Error '{e}' initializing main.py"));
+        .unwrap_or_else(|e| panic!("Error initializing main.py:\n\n{e}\n"));
 }
 
 /// Initializes the plugin.