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Fix overriding static properties in derived classes

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Fixes #775.

Assignments of the form `Type.static_prop = value` should be translated to
`Type.static_prop.__set__(value)` except when `isinstance(value, static_prop)`.
This commit is contained in:
Dean Moldovan 2017-04-06 23:45:12 +02:00
parent db200955b9
commit e0e2ea3378
3 changed files with 28 additions and 2 deletions
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10
include/pybind11/class_support.h
View File

@ -124,8 +124,15 @@ extern "C" inline int pybind11_meta_setattro(PyObject* obj, PyObject* name, PyOb
// descriptor (`property`) instead of calling `tp_descr_get` (`property.__get__()`).
PyObject *descr = _PyType_Lookup((PyTypeObject *) obj, name);
// The following assignment combinations are possible:
// 1. `Type.static_prop = value` --> descr_set: `Type.static_prop.__set__(value)`
// 2. `Type.static_prop = other_static_prop` --> setattro: replace existing `static_prop`
// 3. `Type.regular_attribute = value` --> setattro: regular attribute assignment
const auto static_prop = (PyObject *) get_internals().static_property_type;
const auto call_descr_set = descr && PyObject_IsInstance(descr, static_prop)
&& !PyObject_IsInstance(value, static_prop);
if (call_descr_set) {
// Call `static_property.__set__()` instead of replacing the `static_property`.
if (descr && PyObject_IsInstance(descr, (PyObject *) get_internals().static_property_type)) {
#if !defined(PYPY_VERSION)
return Py_TYPE(descr)->tp_descr_set(descr, obj, value);
#else
@ -137,6 +144,7 @@ extern "C" inline int pybind11_meta_setattro(PyObject* obj, PyObject* name, PyOb
}
#endif
} else {
// Replace existing attribute.
return PyType_Type.tp_setattro(obj, name, value);
}
}

12
tests/test_methods_and_attributes.cpp
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@ -75,6 +75,13 @@ struct TestProperties {
int TestProperties::static_value = 1;
struct TestPropertiesOverride : TestProperties {
int value = 99;
static int static_value;
};
int TestPropertiesOverride::static_value = 99;
struct SimpleValue { int value = 1; };
struct TestPropRVP {
@ -219,6 +226,11 @@ test_initializer methods_and_attributes([](py::module &m) {
[](py::object cls) { return cls; },
[](py::object cls, py::function f) { f(cls); });
py::class_<TestPropertiesOverride, TestProperties>(m, "TestPropertiesOverride")
.def(py::init<>())
.def_readonly("def_readonly", &TestPropertiesOverride::value)
.def_readonly_static("def_readonly_static", &TestPropertiesOverride::static_value);
py::class_<SimpleValue>(m, "SimpleValue")
.def_readwrite("value", &SimpleValue::value);

6
tests/test_methods_and_attributes.py
View File

@ -110,6 +110,12 @@ def test_static_properties():
assert Type.def_readwrite_static == 2
assert instance.def_readwrite_static == 2
# It should be possible to override properties in derived classes
from pybind11_tests import TestPropertiesOverride as TypeOverride
assert TypeOverride().def_readonly == 99
assert TypeOverride.def_readonly_static == 99
def test_static_cls():
"""Static property getter and setters expect the type object as the their only argument"""