Conversion between chrono_tz::Tz and zoneinfo.ZoneInfo

Cargo.toml

@@ -35,6 +35,7 @@ inventory = { version = "0.3.0", optional = true }
 # crate integrations that can be added using the eponymous features
 anyhow = { version = "1.0", optional = true }
 chrono = { version = "0.4.25", default-features = false, optional = true }
+chrono-tz = { version = ">= 0.6, < 0.9", default-features = false, optional = true }
 either = { version = "1.9", optional = true }
 eyre = { version = ">= 0.4, < 0.7", optional = true }
 hashbrown = { version = ">= 0.9, < 0.15", optional = true }
@@ -47,7 +48,8 @@ smallvec = { version = "1.0", optional = true }
 
 [dev-dependencies]
 assert_approx_eq = "1.1.0"
-chrono = { version = "0.4.25" }
+chrono = "0.4.25"
+chrono-tz = ">= 0.6, < 0.9"
 # Required for "and $N others" normalization
 trybuild = ">=1.0.70"
 proptest = { version = "1.0", default-features = false, features = ["std"] }
@@ -108,6 +110,7 @@ full = [
     "macros",
     # "multiple-pymethods", # TODO re-add this when MSRV is greater than 1.62
     "chrono",
+    "chrono-tz",
     "num-bigint",
     "num-complex",
     "hashbrown",

guide/src/features.md

@@ -115,6 +115,12 @@ Adds a dependency on [chrono](https://docs.rs/chrono). Enables a conversion from
 - [NaiveTime](https://docs.rs/chrono/latest/chrono/naive/struct.NaiveTime.html) -> [`PyTime`]({{#PYO3_DOCS_URL}}/pyo3/types/struct.PyTime.html)
 - [DateTime](https://docs.rs/chrono/latest/chrono/struct.DateTime.html) -> [`PyDateTime`]({{#PYO3_DOCS_URL}}/pyo3/types/struct.PyDateTime.html)
 
+### `chrono-tz`
+
+Adds a dependency on [chrono-tz](https://docs.rs/chrono-tz).
+Enables conversion from and to [`Tz`](https://docs.rs/chrono-tz/latest/chrono_tz/enum.Tz.html).
+It requires at least Python 3.9.
+
 ### `either`
 
 Adds a dependency on [either](https://docs.rs/either). Enables a conversions into [either](https://docs.rs/either)’s [`Either`](https://docs.rs/either/latest/either/struct.Report.html) type.

newsfragments/3730.added.md

@@ -0,0 +1 @@
+`chrono-tz` feature allowing conversion between `chrono_tz::Tz` and `zoneinfo.ZoneInfo`

src/conversions/chrono.rs

@@ -9,8 +9,6 @@
 //!
 //! ```toml
 //! [dependencies]
-//! # change * to the latest versions
-//! pyo3 = { version = "*", features = ["chrono"] }
 //! chrono = "0.4"
 #![doc = concat!("pyo3 = { version = \"", env!("CARGO_PKG_VERSION"),  "\", features = [\"chrono\"] }")]
 //! ```
@@ -18,7 +16,7 @@
 //! Note that you must use compatible versions of chrono and PyO3.
 //! The required chrono version may vary based on the version of PyO3.
 //!
-//! # Example: Convert a `PyDateTime` to chrono's `DateTime<Utc>`
+//! # Example: Convert a `datetime.datetime` to chrono's `DateTime<Utc>`
 //!
 //! ```rust
 //! use chrono::{DateTime, Duration, TimeZone, Utc};

src/conversions/chrono_tz.rs

@@ -0,0 +1,113 @@
+#![cfg(all(Py_3_9, feature = "chrono-tz"))]
+
+//! Conversions to and from [chrono-tz](https://docs.rs/chrono-tz/)’s `Tz`.
+//!
+//! This feature requires at least Python 3.9.
+//!
+//! # Setup
+//!
+//! To use this feature, add this to your **`Cargo.toml`**:
+//!
+//! ```toml
+//! [dependencies]
+//! chrono-tz = "0.8"
+#![doc = concat!("pyo3 = { version = \"", env!("CARGO_PKG_VERSION"),  "\", features = [\"chrono-tz\"] }")]
+//! ```
+//!
+//! Note that you must use compatible versions of chrono, chrono-tz and PyO3.
+//! The required chrono version may vary based on the version of PyO3.
+//!
+//! # Example: Convert a `zoneinfo.ZoneInfo` to chrono-tz's `Tz`
+//!
+//! ```rust,no_run
+//! use chrono_tz::Tz;
+//! use pyo3::{Python, ToPyObject};
+//!
+//! fn main() {
+//!     pyo3::prepare_freethreaded_python();
+//!     Python::with_gil(|py| {
+//!         // Convert to Python
+//!         let py_tzinfo = Tz::Europe__Paris.to_object(py);
+//!         // Convert back to Rust
+//!         assert_eq!(py_tzinfo.extract::<Tz>(py).unwrap(), Tz::Europe__Paris);
+//!     });
+//! }
+//! ```
+use crate::exceptions::PyValueError;
+use crate::sync::GILOnceCell;
+use crate::types::PyType;
+use crate::{intern, FromPyObject, IntoPy, Py, PyAny, PyObject, PyResult, Python, ToPyObject};
+use chrono_tz::Tz;
+use std::str::FromStr;
+
+impl ToPyObject for Tz {
+    fn to_object(&self, py: Python<'_>) -> PyObject {
+        static ZONE_INFO: GILOnceCell<Py<PyType>> = GILOnceCell::new();
+        ZONE_INFO
+            .get_or_try_init_type_ref(py, "zoneinfo", "ZoneInfo")
+            .unwrap()
+            .call1((self.name(),))
+            .unwrap()
+            .into()
+    }
+}
+
+impl IntoPy<PyObject> for Tz {
+    fn into_py(self, py: Python<'_>) -> PyObject {
+        self.to_object(py)
+    }
+}
+
+impl FromPyObject<'_> for Tz {
+    fn extract(ob: &PyAny) -> PyResult<Tz> {
+        Tz::from_str(ob.getattr(intern!(ob.py(), "key"))?.extract()?)
+            .map_err(|e| PyValueError::new_err(e.to_string()))
+    }
+}
+
+#[cfg(all(test, not(windows)))] // Troubles loading timezones on Windows
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_frompyobject() {
+        Python::with_gil(|py| {
+            assert_eq!(
+                new_zoneinfo(py, "Europe/Paris").extract::<Tz>().unwrap(),
+                Tz::Europe__Paris
+            );
+            assert_eq!(new_zoneinfo(py, "UTC").extract::<Tz>().unwrap(), Tz::UTC);
+            assert_eq!(
+                new_zoneinfo(py, "Etc/GMT-5").extract::<Tz>().unwrap(),
+                Tz::Etc__GMTMinus5
+            );
+        });
+    }
+
+    #[test]
+    fn test_topyobject() {
+        Python::with_gil(|py| {
+            let assert_eq = |l: PyObject, r: &PyAny| {
+                assert!(l.as_ref(py).eq(r).unwrap());
+            };
+
+            assert_eq(
+                Tz::Europe__Paris.to_object(py),
+                new_zoneinfo(py, "Europe/Paris"),
+            );
+            assert_eq(Tz::UTC.to_object(py), new_zoneinfo(py, "UTC"));
+            assert_eq(
+                Tz::Etc__GMTMinus5.to_object(py),
+                new_zoneinfo(py, "Etc/GMT-5"),
+            );
+        });
+    }
+
+    fn new_zoneinfo<'a>(py: Python<'a>, name: &str) -> &'a PyAny {
+        zoneinfo_class(py).call1((name,)).unwrap()
+    }
+
+    fn zoneinfo_class(py: Python<'_>) -> &PyAny {
+        py.import("zoneinfo").unwrap().getattr("ZoneInfo").unwrap()
+    }
+}

src/conversions/mod.rs

@@ -2,6 +2,7 @@
 
 pub mod anyhow;
 pub mod chrono;
+pub mod chrono_tz;
 pub mod either;
 pub mod eyre;
 pub mod hashbrown;

src/lib.rs

@@ -82,6 +82,7 @@
 //! The following features enable interactions with other crates in the Rust ecosystem:
 //! - [`anyhow`]: Enables a conversion from [anyhow]’s [`Error`][anyhow_error] type to [`PyErr`].
 //! - [`chrono`]: Enables a conversion from [chrono]'s structures to the equivalent Python ones.
+//! - [`chrono-tz`]: Enables a conversion from [chrono-tz]'s `Tz` enum. Requires Python 3.9+.
 //! - [`either`]: Enables conversions between Python objects and [either]'s [`Either`] type.
 //! - [`eyre`]: Enables a conversion from [eyre]’s [`Report`] type to [`PyErr`].
 //! - [`hashbrown`]: Enables conversions between Python objects and [hashbrown]'s [`HashMap`] and
@@ -257,7 +258,9 @@
 //! [`Deserialize`]: https://docs.rs/serde/latest/serde/trait.Deserialize.html
 //! [`Serialize`]: https://docs.rs/serde/latest/serde/trait.Serialize.html
 //! [chrono]: https://docs.rs/chrono/ "Date and Time for Rust."
+//! [chrono-tz]: https://docs.rs/chrono-tz/ "TimeZone implementations for chrono from the IANA database."
 //! [`chrono`]: ./chrono/index.html "Documentation about the `chrono` feature."
+//! [`chrono-tz`]: ./chrono-tz/index.html "Documentation about the `chrono-tz` feature."
 //! [either]: https://docs.rs/either/ "A type that represents one of two alternatives."
 //! [`either`]: ./either/index.html "Documentation about the `either` feature."
 //! [`Either`]: https://docs.rs/either/latest/either/enum.Either.html