fix: implement is_exact_type_of to check dtype and shape for PyArray

src/array.rs

@@ -134,6 +134,10 @@ unsafe impl<T: Element, D: Dimension> PyTypeInfo for PyArray<T, D> {
     fn is_type_of(ob: &Bound<'_, PyAny>) -> bool {
         Self::extract::<IgnoreError>(ob).is_ok()
     }
+
+    fn is_exact_type_of(ob: &Bound<'_, PyAny>) -> bool {
+        Self::extract::<IgnoreError>(ob).is_ok()
+    }
 }
 
 impl<T: Element, D: Dimension> PyArray<T, D> {

tests/array.rs

@@ -251,6 +251,26 @@ fn is_instance() {
     });
 }
 
+#[test]
+fn cast_exact_checks_dtype_and_shape() {
+    Python::attach(|py| {
+        let arr_f64 = PyArray2::<f64>::zeros(py, [3, 5], false);
+        let arr_f32 = PyArray2::<f32>::zeros(py, [3, 5], false);
+        let arr_f64_3d = PyArray::<f64, _>::zeros(py, [3, 5, 7], false);
+
+        // cast_exact should succeed when dtype and shape both match
+        assert!(arr_f64.as_any().cast_exact::<PyArray2<f64>>().is_ok());
+        assert!(arr_f32.as_any().cast_exact::<PyArray2<f32>>().is_ok());
+
+        // cast_exact should fail when dtype does not match
+        assert!(arr_f64.as_any().cast_exact::<PyArray2<f32>>().is_err());
+        assert!(arr_f32.as_any().cast_exact::<PyArray2<f64>>().is_err());
+
+        // cast_exact should fail when dimensionality does not match
+        assert!(arr_f64_3d.as_any().cast_exact::<PyArray2<f64>>().is_err());
+    });
+}
+
 #[test]
 fn from_vec2() {
     Python::attach(|py| {