Backported PyCapsule from 3.1, and converted most uses of

CObject to PyCapsule.

Include/Python.h

@@ -107,6 +107,7 @@
 #include "classobject.h"
 #include "fileobject.h"
 #include "cobject.h"
+#include "pycapsule.h"
 #include "traceback.h"
 #include "sliceobject.h"
 #include "cellobject.h"

Include/cStringIO.h

@@ -18,9 +18,12 @@ extern "C" {
   This would typically be done in your init function.
 
 */
+
+#define PycStringIO_CAPSULE_NAME "cStringIO.cStringIO_CAPI"
+
 #define PycString_IMPORT \
-  PycStringIO = (struct PycStringIO_CAPI*)PyCObject_Import("cStringIO", \
-                                                           "cStringIO_CAPI")
+  PycStringIO = ((struct PycStringIO_CAPI*)PyCapsule_Import(\
+    PycStringIO_CAPSULE_NAME, 0))
 
 /* Basic functions to manipulate cStringIO objects from C */
 

Include/cobject.h

@@ -6,6 +6,8 @@
    to other extension modules, so that extension modules can use the
    Python import mechanism to link to one another.
 
+   DEPRECATED - Use PyCapsule objects instead.
+                CObject will be removed in 2.8 (if there is one).
 */
 
 #ifndef Py_COBJECT_H

Include/datetime.h

@@ -158,6 +158,8 @@ typedef struct {
 
 } PyDateTime_CAPI;
 
+#define PyDateTime_CAPSULE_NAME "datetime.datetime_CAPI"
+
 
 /* "magic" constant used to partially protect against developer mistakes. */
 #define DATETIME_API_MAGIC 0x414548d5
@@ -186,15 +188,7 @@ typedef struct {
 static PyDateTime_CAPI *PyDateTimeAPI = NULL;
 
 #define PyDateTime_IMPORT \
-        PyDateTimeAPI = (PyDateTime_CAPI*) PyCObject_Import("datetime", \
-                                                            "datetime_CAPI")
-
-/* This macro would be used if PyCObject_ImportEx() was created.
-#define PyDateTime_IMPORT \
-        PyDateTimeAPI = (PyDateTime_CAPI*) PyCObject_ImportEx("datetime", \
-                                                            "datetime_CAPI", \
-                                                            DATETIME_API_MAGIC)
-*/
+        PyDateTimeAPI = (PyDateTime_CAPI *)PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)
 
 /* Macros for type checking when not building the Python core. */
 #define PyDate_Check(op) PyObject_TypeCheck(op, PyDateTimeAPI->DateType)

Include/py_curses.h

@@ -80,6 +80,9 @@ typedef struct {
 
 #define PyCursesWindow_Check(v)	 (Py_TYPE(v) == &PyCursesWindow_Type)
 
+#define PyCurses_CAPSULE_NAME "_curses._C_API"
+
+
 #ifdef CURSES_MODULE
 /* This section is used when compiling _cursesmodule.c */
 
@@ -94,16 +97,8 @@ static void **PyCurses_API;
 #define PyCursesInitialisedColor {if (! ((int (*)(void))PyCurses_API[3]) () ) return NULL;}
 
 #define import_curses() \
-{ \
-  PyObject *module = PyImport_ImportModuleNoBlock("_curses"); \
-  if (module != NULL) { \
-    PyObject *module_dict = PyModule_GetDict(module); \
-    PyObject *c_api_object = PyDict_GetItemString(module_dict, "_C_API"); \
-    if (PyCObject_Check(c_api_object)) { \
-      PyCurses_API = (void **)PyCObject_AsVoidPtr(c_api_object); \
-    } \
-  } \
-}
+    PyCurses_API = (void **)PyCapsule_Import(PyCurses_CAPSULE_NAME, 1);
+
 #endif
 
 /* general error messages */

Include/pycapsule.h

@@ -0,0 +1,148 @@
+
+/* Capsule objects let you wrap a C "void *" pointer in a Python
+   object.  They're a way of passing data through the Python interpreter
+   without creating your own custom type.
+
+   Capsules are used for communication between extension modules.
+   They provide a way for an extension module to export a C interface
+   to other extension modules, so that extension modules can use the
+   Python import mechanism to link to one another.
+
+   For more information, please see "c-api/capsule.html" in the
+   documentation.
+*/
+
+#ifndef Py_CAPSULE_H
+#define Py_CAPSULE_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+PyAPI_DATA(PyTypeObject) PyCapsule_Type;
+
+typedef void (*PyCapsule_Destructor)(PyObject *);
+
+#define PyCapsule_CheckExact(op) (Py_TYPE(op) == &PyCapsule_Type)
+
+
+PyAPI_FUNC(PyObject *) PyCapsule_New(
+    void *pointer,
+    const char *name,
+    PyCapsule_Destructor destructor);
+
+PyAPI_FUNC(void *) PyCapsule_GetPointer(PyObject *capsule, const char *name);
+
+PyAPI_FUNC(PyCapsule_Destructor) PyCapsule_GetDestructor(PyObject *capsule);
+
+PyAPI_FUNC(const char *) PyCapsule_GetName(PyObject *capsule);
+
+PyAPI_FUNC(void *) PyCapsule_GetContext(PyObject *capsule);
+
+PyAPI_FUNC(int) PyCapsule_IsValid(PyObject *capsule, const char *name);
+
+PyAPI_FUNC(int) PyCapsule_SetPointer(PyObject *capsule, void *pointer);
+
+PyAPI_FUNC(int) PyCapsule_SetDestructor(PyObject *capsule, PyCapsule_Destructor destructor);
+
+PyAPI_FUNC(int) PyCapsule_SetName(PyObject *capsule, const char *name);
+
+PyAPI_FUNC(int) PyCapsule_SetContext(PyObject *capsule, void *context);
+
+PyAPI_FUNC(void *) PyCapsule_Import(const char *name, int no_block);
+
+
+#define PYTHON_USING_CAPSULE
+
+#define PYCAPSULE_INSTANTIATE_DESTRUCTOR(name, destructor) \
+static void pycapsule_destructor_ ## name(PyObject *ptr) \
+{ \
+	void *p = PyCapsule_GetPointer(ptr, name); \
+	if (p) { \
+		destructor(p); \
+	} \
+} \
+
+#define PYCAPSULE_NEW(pointer, name) \
+	(PyCapsule_New(pointer, name, capsule_destructor_ ## name))
+
+#define PYCAPSULE_ISVALID(capsule, name) \
+  (PyCapsule_IsValid(capsule, name))
+
+#define PYCAPSULE_DEREFERENCE(capsule, name) \
+  (PyCapsule_GetPointer(capsule, name))
+
+#define PYCAPSULE_SET(capsule, name, value) \
+  (PyCapsule_IsValid(capsule, name) && PyCapsule_SetPointer(capsule, value))
+
+/* module and attribute should be specified as string constants */
+#define PYCAPSULE_IMPORT(module, attribute) \
+  (PyCapsule_Import(module "." attribute, 0))
+
+
+/* begin public-domain code */
+/* 
+** This code was written by Larry Hastings, 
+** and is dedicated to the public domain. 
+** It's designed to make it easy to switch 
+** from CObject to Capsule objects without losing 
+** backwards compatibility with prior versions 
+** of CPython.  You're encouraged to copy this code 
+** (including this documentation) into your 
+** Python C extension.
+** 
+** To use: 
+**    * #define a name for the pointer you store in
+**      the CObject.  If you make the CObject available
+**      as part of your module's API, this name should
+**      be "modulename.attributename", and it should be
+**      considered part of your API (so put it in your
+**      header file).
+**    * Specify a PYCAPSULE_INSTANTIATE_DESTRUCTOR(), in
+**      every C file that creates these CObjects.  This
+**      is where you specify your object's destructor.
+**    * Change all calls to CObject_FromVoidPtr()
+**      and CObject_FromVoidPointerAndDesc() into
+**      PYCAPSULE_NEW() calls.
+**    * Change all calls to PyCObject_AsVoidPtr()
+**      into PYCAPSULE_DEREFERENCE() calls.
+**    * Change all calls to PyCObject_SetVoidPtr()
+**      into PYCAPSULE_SET() calls.
+**    * Change all calls to PyCObject_Import()
+**      into PYCAPSULE_IMPORT() calls.  Note that
+**      the two arguments to PYCAPSULE_IMPORT()
+**      should both be string constants; that is,
+**      you should call
+**      PYCAPSULE_IMPORT("modulename", "attributename"),
+**      not PYCAPSULE_IMPORT(charstar1, charstar2).
+*/
+#ifndef PYTHON_USING_CAPSULE
+
+#define PYCAPSULE_INSTANTIATE_DESTRUCTOR(name, destructor) \
+static void pycapsule_destructor_ ## name(void *ptr) \
+{ \
+	destructor(p); \
+} \
+
+#define PYCAPSULE_NEW(pointer, name) \
+	(PyCObject_FromVoidPtr(pointer, pycapsule_destructor_ ## name))
+
+#define PYCAPSULE_ISVALID(capsule, name) \
+  (PyCObject_Check(capsule))
+
+#define PYCAPSULE_DEREFERENCE(capsule, name) \
+  (PyCObject_AsVoidPtr(capsule))
+
+#define PYCAPSULE_SET(capsule, name, value) \
+  (PyCObject_SetVoidPtr(capsule, value))
+
+/* module and attribute should be specified as string constants */
+#define PYCAPSULE_IMPORT(module, attribute) \
+  (PyCObject_Import(module, attribute))
+
+#endif /* PYTHON_USING_CAPSULE */
+/* end public-domain code */
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_CAPSULE_H */

Include/pyexpat.h

@@ -4,6 +4,7 @@
 /* note: you must import expat.h before importing this module! */
 
 #define PyExpat_CAPI_MAGIC  "pyexpat.expat_CAPI 1.0"
+#define PyExpat_CAPSULE_NAME "pyexpat.expat_CAPI"
 
 struct PyExpat_CAPI 
 {

Include/ucnhash.h

@@ -6,7 +6,9 @@
 extern "C" {
 #endif
 
-/* revised ucnhash CAPI interface (exported through a PyCObject) */
+/* revised ucnhash CAPI interface (exported through a "wrapper") */
+
+#define PyUnicodeData_CAPSULE_NAME "unicodedata.ucnhash_CAPI"
 
 typedef struct {