Merge pull request #57 from tmiasko/conversion

Use object class to hold partially converted python objects.

docs/reference.rst

@@ -59,7 +59,7 @@ Without reference counting
 
     Creates a :class:`handle` from the given raw Python object pointer.
 
-.. function:: PyObject * handle::ptr()
+.. function:: PyObject * handle::ptr() const
 
     Return the ``PyObject *`` underlying a :class:`handle`.
 
@@ -167,6 +167,12 @@ With reference counting
     Move constructor; steals the object from ``other`` and preserves its
     reference count.
 
+.. function:: PyObject* object::release()
+
+    Release ownership of underlying ``PyObject *``. Returns raw Python object
+    pointer without decreasing its reference count and resets handle to
+    ``nullptr``-valued pointer.
+
 .. function:: object::~object()
 
     Constructor, which automatically calls :func:`handle::dec_ref()`.

include/pybind11/cast.h

@@ -398,16 +398,15 @@ public:
     }
 
     static PyObject *cast(const type &src, return_value_policy policy, PyObject *parent) {
-        PyObject *o1 = type_caster<typename decay<T1>::type>::cast(src.first, policy, parent);
-        PyObject *o2 = type_caster<typename decay<T2>::type>::cast(src.second, policy, parent);
-        if (!o1 || !o2) {
-            Py_XDECREF(o1);
-            Py_XDECREF(o2);
+        object o1(type_caster<typename decay<T1>::type>::cast(src.first, policy, parent), false);
+        object o2(type_caster<typename decay<T2>::type>::cast(src.second, policy, parent), false);
+        if (!o1 || !o2)
             return nullptr;
-        }
         PyObject *tuple = PyTuple_New(2);
-        PyTuple_SetItem(tuple, 0, o1);
-        PyTuple_SetItem(tuple, 1, o2);
+        if (!tuple)
+            return nullptr;
+        PyTuple_SetItem(tuple, 0, o1.release());
+        PyTuple_SetItem(tuple, 1, o2.release());
         return tuple;
     }
 
@@ -502,25 +501,19 @@ protected:
 
     /* Implementation: Convert a C++ tuple into a Python tuple */
     template <size_t ... Indices> static PyObject *cast(const type &src, return_value_policy policy, PyObject *parent, index_sequence<Indices...>) {
-        std::array<PyObject *, size> results {{
-            type_caster<typename decay<Tuple>::type>::cast(std::get<Indices>(src), policy, parent)...
+        std::array<object, size> results {{
+            object(type_caster<typename decay<Tuple>::type>::cast(std::get<Indices>(src), policy, parent), false)...
         }};
-        bool success = true;
-        for (auto result : results)
-            if (result == nullptr)
-                success = false;
-        if (success) {
-            PyObject *tuple = PyTuple_New(size);
-            int counter = 0;
-            for (auto result : results)
-                PyTuple_SetItem(tuple, counter++, result);
-            return tuple;
-        } else {
-            for (auto result : results) {
-                Py_XDECREF(result);
-            }
+        for (const auto & result : results)
+            if (!result)
+                return nullptr;
+        PyObject *tuple = PyTuple_New(size);
+        if (!tuple)
             return nullptr;
-        }
+        int counter = 0;
+        for (auto & result : results)
+            PyTuple_SetItem(tuple, counter++, result.release());
+        return tuple;
     }
 
 protected:
@@ -600,26 +593,20 @@ template <> inline void handle::cast() const { return; }
 
 template <typename... Args> inline object handle::call(Args&&... args_) {
     const size_t size = sizeof...(Args);
-    std::array<PyObject *, size> args{
-        { detail::type_caster<typename detail::decay<Args>::type>::cast(
-            std::forward<Args>(args_), return_value_policy::reference, nullptr)... }
+    std::array<object, size> args{
+        { object(detail::type_caster<typename detail::decay<Args>::type>::cast(
+            std::forward<Args>(args_), return_value_policy::reference, nullptr), false)... }
     };
-    bool fail = false;
-    for (auto result : args)
-        if (result == nullptr)
-            fail = true;
-    if (fail) {
-        for (auto result : args) {
-            Py_XDECREF(result);
-        }
+    for (const auto & result : args)
+        if (!result)
+            throw cast_error("handle::call(): unable to convert input arguments to Python objects");
+    object tuple(PyTuple_New(size), false);
+    if (!tuple)
         throw cast_error("handle::call(): unable to convert input arguments to Python objects");
-    }
-    PyObject *tuple = PyTuple_New(size);
     int counter = 0;
-    for (auto result : args)
-        PyTuple_SetItem(tuple, counter++, result);
-    PyObject *result = PyObject_CallObject(m_ptr, tuple);
-    Py_DECREF(tuple);
+    for (auto & result : args)
+        PyTuple_SetItem(tuple.ptr(), counter++, result.release());
+    PyObject *result = PyObject_CallObject(m_ptr, tuple.ptr());
     if (result == nullptr && PyErr_Occurred())
         throw error_already_set();
     return object(result, false);

include/pybind11/pytypes.h

@@ -29,8 +29,7 @@ public:
     handle() : m_ptr(nullptr) { }
     handle(const handle &other) : m_ptr(other.m_ptr) { }
     handle(PyObject *ptr) : m_ptr(ptr) { }
-    PyObject *ptr() { return m_ptr; }
-    const PyObject *ptr() const { return m_ptr; }
+    PyObject *ptr() const { return m_ptr; }
     void inc_ref() const { Py_XINCREF(m_ptr); }
     void dec_ref() const { Py_XDECREF(m_ptr); }
     int ref_count() const { return (int) Py_REFCNT(m_ptr); }
@@ -60,6 +59,12 @@ public:
     object(object &&other) { m_ptr = other.m_ptr; other.m_ptr = nullptr; }
     ~object() { dec_ref(); }
 
+    PyObject * release() {
+      PyObject *tmp = m_ptr;
+      m_ptr = nullptr;
+      return tmp;
+    }
+
     object& operator=(object &other) {
         Py_XINCREF(other.m_ptr);
         Py_XDECREF(m_ptr);

include/pybind11/stl.h

@@ -43,17 +43,17 @@ public:
     }
 
     static PyObject *cast(const type &src, return_value_policy policy, PyObject *parent) {
-        PyObject *list = PyList_New(src.size());
+        object list(PyList_New(src.size()), false);
+        if (!list)
+          return nullptr;
         size_t index = 0;
         for (auto const &value: src) {
-            PyObject *value_ = value_conv::cast(value, policy, parent);
-            if (!value_) {
-                Py_DECREF(list);
+            object value_ (value_conv::cast(value, policy, parent), false);
+            if (!value_)
                 return nullptr;
-            }
-            PyList_SET_ITEM(list, index++, value_); // steals a reference
+            PyList_SET_ITEM(list.ptr(), index++, value_.release()); // steals a reference
         }
-        return list;
+        return list.release();
     }
     PYBIND11_TYPE_CASTER(type, detail::descr("list<") + value_conv::name() + detail::descr(">"));
 };
@@ -77,17 +77,15 @@ public:
     }
 
     static PyObject *cast(const type &src, return_value_policy policy, PyObject *parent) {
-        PyObject *set = PySet_New(nullptr);
+        object set(PySet_New(nullptr), false);
+        if (!set)
+          return nullptr;
         for (auto const &value: src) {
-            PyObject *value_ = value_conv::cast(value, policy, parent);
-            if (!value_ || PySet_Add(set, value_) != 0) {
-                Py_XDECREF(value_);
-                Py_DECREF(set);
+            object value_(value_conv::cast(value, policy, parent), false);
+            if (!value_ || PySet_Add(set.ptr(), value_.ptr()) != 0)
                 return nullptr;
-            }
-            Py_DECREF(value_);
         }
-        return set;
+        return set.release();
     }
     PYBIND11_TYPE_CASTER(type, detail::descr("set<") + value_conv::name() + detail::descr(">"));
 };
@@ -116,20 +114,16 @@ public:
     }
 
     static PyObject *cast(const type &src, return_value_policy policy, PyObject *parent) {
-        PyObject *dict = PyDict_New();
+        object dict(PyDict_New(), false);
+        if (!dict)
+          return nullptr;
         for (auto const &kv: src) {
-            PyObject *key   = key_conv::cast(kv.first, policy, parent);
-            PyObject *value = value_conv::cast(kv.second, policy, parent);
-            if (!key || !value || PyDict_SetItem(dict, key, value) != 0) {
-                Py_XDECREF(key);
-                Py_XDECREF(value);
-                Py_DECREF(dict);
+            object key(key_conv::cast(kv.first, policy, parent), false);
+            object value(value_conv::cast(kv.second, policy, parent), false);
+            if (!key || !value || PyDict_SetItem(dict.ptr(), key.ptr(), value.ptr()) != 0)
                 return nullptr;
-            }
-            Py_DECREF(key);
-            Py_DECREF(value);
         }
-        return dict;
+        return dict.release();
     }
 
     PYBIND11_TYPE_CASTER(type, detail::descr("dict<") + key_conv::name() + detail::descr(", ") + value_conv::name() + detail::descr(">"));