functional: support bound methods
If a bound std::function is invoked with a bound method, the implicit
bound self is lost because we use `detail::get_function` to unbox the
function. This commit amends the code to use py::function and only
unboxes in the special is-really-a-c-function case. This makes bound
methods stay bound rather than unbinding them by forcing extraction of
the c function.
diff --git a/include/pybind11/functional.h b/include/pybind11/functional.h
index a99ee73..ab9e1c3 100644
--- a/include/pybind11/functional.h
+++ b/include/pybind11/functional.h
@@ -22,14 +22,15 @@
using function_type = Return (*) (Args...);
public:
- bool load(handle src_, bool) {
- if (src_.is_none())
+ bool load(handle src, bool) {
+ if (src.is_none())
return true;
- src_ = detail::get_function(src_);
- if (!src_ || !PyCallable_Check(src_.ptr()))
+ if (!isinstance<function>(src))
return false;
+ auto func = reinterpret_borrow<function>(src);
+
/*
When passing a C++ function as an argument to another C++
function via Python, every function call would normally involve
@@ -38,8 +39,8 @@
stateless (i.e. function pointer or lambda function without
captured variables), in which case the roundtrip can be avoided.
*/
- if (PyCFunction_Check(src_.ptr())) {
- auto c = reinterpret_borrow<capsule>(PyCFunction_GET_SELF(src_.ptr()));
+ if (auto cfunc = func.cpp_function()) {
+ auto c = reinterpret_borrow<capsule>(PyCFunction_GET_SELF(cfunc.ptr()));
auto rec = (function_record *) c;
if (rec && rec->is_stateless && rec->data[1] == &typeid(function_type)) {
@@ -49,10 +50,9 @@
}
}
- auto src = reinterpret_borrow<object>(src_);
- value = [src](Args... args) -> Return {
+ value = [func](Args... args) -> Return {
gil_scoped_acquire acq;
- object retval(src(std::forward<Args>(args)...));
+ object retval(func(std::forward<Args>(args)...));
/* Visual studio 2015 parser issue: need parentheses around this expression */
return (retval.template cast<Return>());
};
diff --git a/include/pybind11/pytypes.h b/include/pybind11/pytypes.h
index b7317df..26f5ae4 100644
--- a/include/pybind11/pytypes.h
+++ b/include/pybind11/pytypes.h
@@ -355,6 +355,7 @@
#if PY_MAJOR_VERSION >= 3
if (PyInstanceMethod_Check(value.ptr()))
value = PyInstanceMethod_GET_FUNCTION(value.ptr());
+ else
#endif
if (PyMethod_Check(value.ptr()))
value = PyMethod_GET_FUNCTION(value.ptr());
@@ -1133,10 +1134,13 @@
class function : public object {
public:
PYBIND11_OBJECT_DEFAULT(function, object, PyCallable_Check)
- bool is_cpp_function() const {
+ handle cpp_function() const {
handle fun = detail::get_function(m_ptr);
- return fun && PyCFunction_Check(fun.ptr());
+ if (fun && PyCFunction_Check(fun.ptr()))
+ return fun;
+ return handle();
}
+ bool is_cpp_function() const { return (bool) cpp_function(); }
};
class buffer : public object {
diff --git a/tests/test_callbacks.cpp b/tests/test_callbacks.cpp
index f89cc1c..4111008 100644
--- a/tests/test_callbacks.cpp
+++ b/tests/test_callbacks.cpp
@@ -179,4 +179,9 @@
f(x); // lvalue reference shouldn't move out object
return x.valid; // must still return `true`
});
+
+ struct CppBoundMethodTest {};
+ py::class_<CppBoundMethodTest>(m, "CppBoundMethodTest")
+ .def(py::init<>())
+ .def("triple", [](CppBoundMethodTest &, int val) { return 3 * val; });
});
diff --git a/tests/test_callbacks.py b/tests/test_callbacks.py
index f94e7b6..a5109d0 100644
--- a/tests/test_callbacks.py
+++ b/tests/test_callbacks.py
@@ -27,6 +27,21 @@
assert f(number=43) == 44
+def test_bound_method_callback():
+ from pybind11_tests import test_callback3, CppBoundMethodTest
+
+ # Bound Python method:
+ class MyClass:
+ def double(self, val):
+ return 2 * val
+
+ z = MyClass()
+ assert test_callback3(z.double) == "func(43) = 86"
+
+ z = CppBoundMethodTest()
+ assert test_callback3(z.triple) == "func(43) = 129"
+
+
def test_keyword_args_and_generalized_unpacking():
from pybind11_tests import (test_tuple_unpacking, test_dict_unpacking, test_keyword_args,
test_unpacking_and_keywords1, test_unpacking_and_keywords2,