From cedac43dbb90b191a6233d52493610ae521d8a14 Mon Sep 17 00:00:00 2001
From: David Hewitt <mail@davidhewitt.dev>
Date: Wed, 20 Mar 2024 12:52:09 +0000
Subject: [PATCH] add Bound::as_unbound (#3973)

* add Bound::as_unbound

* Update src/instance.rs
---
 src/instance.rs | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/src/instance.rs b/src/instance.rs
index 024a9fe5..5f054d0d 100644
--- a/src/instance.rs
+++ b/src/instance.rs
@@ -465,6 +465,13 @@ impl<'py, T> Bound<'py, T> {
         unsafe { Py::from_non_null(non_null) }
     }
 
+    /// Removes the connection for this `Bound<T>` from the GIL, allowing
+    /// it to cross thread boundaries, without transferring ownership.
+    #[inline]
+    pub fn as_unbound(&self) -> &Py<T> {
+        &self.1
+    }
+
     /// Casts this `Bound<T>` as the corresponding "GIL Ref" type.
     ///
     /// This is a helper to be used for migration from the deprecated "GIL Refs" API.
@@ -521,11 +528,11 @@ impl<'py, T> Borrowed<'_, 'py, T> {
     /// # fn main() -> PyResult<()> {
     /// Python::with_gil(|py| -> PyResult<()> {
     ///     let tuple = PyTuple::new_bound(py, [1, 2, 3]);
-    ///     
+    ///
     ///     // borrows from `tuple`, so can only be
     ///     // used while `tuple` stays alive
     ///     let borrowed = tuple.get_borrowed_item(0)?;
-    ///     
+    ///
     ///     // creates a new owned reference, which
     ///     // can be used indendently of `tuple`
     ///     let bound = borrowed.to_owned();
@@ -1960,8 +1967,8 @@ impl PyObject {
 mod tests {
     use super::{Bound, Py, PyObject};
     use crate::types::any::PyAnyMethods;
-    use crate::types::PyCapsule;
     use crate::types::{dict::IntoPyDict, PyDict, PyString};
+    use crate::types::{PyCapsule, PyStringMethods};
     use crate::{ffi, Borrowed, PyAny, PyNativeType, PyResult, Python, ToPyObject};
 
     #[test]
@@ -2161,6 +2168,20 @@ a = A()
         });
     }
 
+    #[test]
+    fn test_bound_py_conversions() {
+        Python::with_gil(|py| {
+            let obj: Bound<'_, PyString> = PyString::new_bound(py, "hello world");
+            let obj_unbound: &Py<PyString> = obj.as_unbound();
+            let _: &Bound<'_, PyString> = obj_unbound.bind(py);
+
+            let obj_unbound: Py<PyString> = obj.unbind();
+            let obj: Bound<'_, PyString> = obj_unbound.into_bound(py);
+
+            assert_eq!(obj.to_cow().unwrap(), "hello world");
+        });
+    }
+
     #[test]
     fn bound_from_borrowed_ptr_constructors() {
         // More detailed tests of the underlying semantics in pycell.rs