use last segment of module name (path) when adding to parent

newsfragments/5375.fixed.md

@@ -0,0 +1 @@
+Fixed `PyModuleMethods::add_submodul()` to use the last segment of the submodule name as the attribute name on the parent module instead of using the full name.

src/types/module.rs

@@ -35,7 +35,8 @@ pub struct PyModule(PyAny);
 pyobject_native_type_core!(PyModule, pyobject_native_static_type_object!(ffi::PyModule_Type), #checkfunction=ffi::PyModule_Check);
 
 impl PyModule {
-    /// Creates a new module object with the `__name__` attribute set to `name`.
+    /// Creates a new module object with the `__name__` attribute set to `name`.  When creating
+    /// a submodule pass the full path as the name such as `top_level.name`.
     ///
     /// # Examples
     ///
@@ -514,7 +515,11 @@ impl<'py> PyModuleMethods<'py> for Bound<'py, PyModule> {
     }
 
     fn add_submodule(&self, module: &Bound<'_, PyModule>) -> PyResult<()> {
-        let name = module.name()?;
+        let name = module
+            .name()?
+            .call_method1("rpartition", (".",))?
+            .get_item(2)?
+            .downcast_into::<PyString>()?;
         self.add(name, module)
     }
 

tests/test_module.rs

@@ -285,10 +285,10 @@ fn superfunction() -> String {
 #[pymodule]
 fn supermodule(module: &Bound<'_, PyModule>) -> PyResult<()> {
     module.add_function(wrap_pyfunction!(superfunction, module)?)?;
-    let module_to_add = PyModule::new(module.py(), "submodule")?;
+    let module_to_add = PyModule::new(module.py(), "supermodule.submodule")?;
     submodule(&module_to_add)?;
     module.add_submodule(&module_to_add)?;
-    let module_to_add = PyModule::new(module.py(), "submodule_with_init_fn")?;
+    let module_to_add = PyModule::new(module.py(), "supermodule.submodule_with_init_fn")?;
     submodule_with_init_fn(&module_to_add)?;
     module.add_submodule(&module_to_add)?;
     Ok(())
@@ -316,6 +316,36 @@ fn test_module_nesting() {
             supermodule,
             "supermodule.submodule_with_init_fn.subfunction() == 'Subfunction'"
         );
+
+        // submodule dunder name and attribute name
+        py_assert!(
+            py,
+            supermodule,
+            "supermodule.submodule.__name__ == 'supermodule.submodule'"
+        );
+        py_assert!(py, supermodule, "'submodule' in supermodule.__dict__");
+        py_assert!(
+            py,
+            supermodule,
+            "'supermodule.submodule' not in supermodule.__dict__"
+        );
+
+        // submodule_with_init_fn dunder name and attribute name
+        py_assert!(
+            py,
+            supermodule,
+            "supermodule.submodule_with_init_fn.__name__ == 'supermodule.submodule_with_init_fn'"
+        );
+        py_assert!(
+            py,
+            supermodule,
+            "'submodule_with_init_fn' in supermodule.__dict__"
+        );
+        py_assert!(
+            py,
+            supermodule,
+            "'supermodule.submodule_with_init_fn' not in supermodule.__dict__"
+        );
     });
 }