Add anyhow-integration feature which implements From<anyhow::Error> for PyErr

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Add `PyAny::py()` as a convenience for `PyNativeType::py()`. [#1751](https://github.com/PyO3/pyo3/pull/1751)
 - Add implementation of `std::ops::Index<usize>` for `PyList`, `PyTuple` and `PySequence`. [#1825](https://github.com/PyO3/pyo3/pull/1825)
 - Add range indexing implementations of `std::ops::Index` for `PyList`, `PyTuple` and `PySequence`. [#1829](https://github.com/PyO3/pyo3/pull/1829)
+- Add `anyhow` feature which provides `impl From<anyhow::Error> for PyErr`. [#1822](https://github.com/PyO3/pyo3/pull/1822)
 
 ### Changed
 

Cargo.toml

@@ -29,6 +29,7 @@ unindent = { version = "0.1.4", optional = true }
 hashbrown = { version = ">= 0.9, < 0.12", optional = true }
 indexmap = { version = ">= 1.6, < 1.8", optional = true }
 serde = {version = "1.0", optional = true}
+anyhow = { version = "1.0", optional = true }
 
 [dev-dependencies]
 assert_approx_eq = "1.1.0"

guide/src/features.md

@@ -109,3 +109,7 @@ struct User {
     permissions: Vec<Py<Permission>>
 }
 ```
+
+### `anyhow`
+
+This feature makes it possible to return [`anyhow::Result<T>`](https://docs.rs/anyhow/1.0.43/anyhow/type.Result.html) from functions and methods exposed to Python. It does so by adding `impl From<anyhow::Error> for PyErr`. Currently, the conversion simply stringifies the `anyhow::Error` and shoves it into a `PyRuntimeError`. As a consequence, there is no way to convert a `PyErr` back to the original `anyhow::Error`. It is mostly intended as a developer convenience.

src/conversions/anyhow.rs

@@ -0,0 +1,41 @@
+use crate::exceptions::PyRuntimeError;
+use crate::PyErr;
+
+impl From<anyhow::Error> for PyErr {
+    fn from(err: anyhow::Error) -> Self {
+        PyRuntimeError::new_err(format!("{:?}", err))
+    }
+}
+
+#[cfg(test)]
+mod test_anyhow {
+    use crate::proc_macro::pyfunction;
+    use crate::py_run;
+    use crate::wrap_pyfunction;
+    use crate::{Python, ToPyObject};
+
+    #[pyfunction]
+    fn produce_ok_result() -> anyhow::Result<String> {
+        Ok(String::from("OK buddy"))
+    }
+
+    #[pyfunction]
+    fn produce_err_result() -> anyhow::Result<String> {
+        anyhow::bail!("error time")
+    }
+
+    #[test]
+    fn test_anyhow_py_function_ok_result() {
+        Python::with_gil(|py| {
+            let func = wrap_pyfunction!(produce_ok_result)(py).unwrap();
+
+            py_run!(
+                py,
+                func,
+                r#"
+            func()
+            "#
+            );
+        });
+    }
+}

src/conversions/mod.rs

@@ -6,3 +6,5 @@ mod array;
 pub mod indexmap;
 mod osstr;
 mod path;
+#[cfg(feature = "anyhow")]
+pub mod anyhow;