From 6db9587c2810cc33e0ba37be815be212d212b65a Mon Sep 17 00:00:00 2001
From: konstin <konstin@mailbox.org>
Date: Wed, 5 Jun 2019 11:32:46 +0200
Subject: [PATCH] Use existing fields and methods before calling custom
__getattr__
Previously, defining `__getattr__` would override all existing fields and methods. This changes it to behave like a `__getattr__` method defined in python, i.e. the custom method is only called if there isn't a field or method of that name
---
CHANGELOG.md | 1 +
src/class/basic.rs | 37 +++++++++++++++++++++++++++++++------
2 files changed, 32 insertions(+), 6 deletions(-)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index beb3e35d02d..fe366d975dc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
### Added
* `module` argument to `pyclass` macro. [#499](https://github.com/PyO3/pyo3/pull/499)
+ * Use existing fields and methods before calling custom __getattr__.
## [0.7.0] - 2018-05-26
diff --git a/src/class/basic.rs b/src/class/basic.rs
index ed71e2d9d73..a23c271801a 100644
--- a/src/class/basic.rs
+++ b/src/class/basic.rs
@@ -207,12 +207,37 @@ where
T: for<'p> PyObjectGetAttrProtocol<'p>,
{
fn tp_getattro() -> Option<ffi::binaryfunc> {
- py_binary_func!(
- PyObjectGetAttrProtocol,
- T::__getattr__,
- T::Success,
- PyObjectCallbackConverter
- )
+ #[allow(unused_mut)]
+ unsafe extern "C" fn wrap<T>(
+ slf: *mut ffi::PyObject,
+ arg: *mut ffi::PyObject,
+ ) -> *mut ffi::PyObject
+ where
+ T: for<'p> PyObjectGetAttrProtocol<'p>,
+ {
+ let _pool = crate::GILPool::new();
+ let py = Python::assume_gil_acquired();
+
+ // Behave like python's __getattr__ (as opposed to __getattribute__) and check
+ // for existing fields and methods first
+ let existing = ffi::PyObject_GenericGetAttr(slf, arg);
+ if existing == std::ptr::null_mut() {
+ // PyObject_HasAttr also tries to get an object and clears the error if it fails
+ ffi::PyErr_Clear();
+ } else {
+ return existing;
+ }
+
+ let slf = py.mut_from_borrowed_ptr::<T>(slf);
+ let arg = py.from_borrowed_ptr::<crate::types::PyAny>(arg);
+
+ let result = match arg.extract() {
+ Ok(arg) => slf.__getattr__(arg).into(),
+ Err(e) => Err(e.into()),
+ };
+ crate::callback::cb_convert(PyObjectCallbackConverter, py, result)
+ }
+ Some(wrap::<T>)
}
}