#1087741: make mmap.mmap the type of mmap objects, not a

factory function. Allow it to be subclassed.

3 files changed, 39 insertions, 27 deletions

diff --git a/Doc/library/mmap.rst b/Doc/library/mmap.rst
index cdc761c..7034457 100644
--- a/Doc/library/mmap.rst
+++ b/Doc/library/mmap.rst
@@ -15,7 +15,7 @@ substring by assigning to a slice: ``obj[i1:i2] = '...'``.  You can also read
 and write data starting at the current file position, and :meth:`seek` through
 the file to different positions.
 
-A memory-mapped file is created by the :func:`mmap` function, which is different
+A memory-mapped file is created by the :class:`mmap` constructor, which is different
 on Unix and on Windows.  In either case you must provide a file descriptor for a
 file opened for update. If you wish to map an existing Python file object, use
 its :meth:`fileno` method to obtain the correct value for the *fileno*
@@ -23,7 +23,7 @@ parameter.  Otherwise, you can open the file using the :func:`os.open` function,
 which returns a file descriptor directly (the file still needs to be closed when
 done).
 
-For both the Unix and Windows versions of the function, *access* may be
+For both the Unix and Windows versions of the constructor, *access* may be
 specified as an optional keyword parameter. *access* accepts one of three
 values: :const:`ACCESS_READ`, :const:`ACCESS_WRITE`, or :const:`ACCESS_COPY` to
 specify readonly, write-through or copy-on-write memory respectively. *access*
@@ -39,11 +39,14 @@ not update the underlying file.
    To map anonymous memory, -1 should be passed as the fileno along with the
    length.
 
+.. versionchanged:: 2.6
+   mmap.mmap has formerly been a factory function creating mmap objects. Now 
+   mmap.mmap is the class itself.
 
-.. function:: mmap(fileno, length[, tagname[, access[, offset]]])
+.. class:: mmap(fileno, length[, tagname[, access[, offset]]])
 
    **(Windows version)** Maps *length* bytes from the file specified by the file
-   handle *fileno*, and returns a mmap object.  If *length* is larger than the
+   handle *fileno*, and creates a mmap object.  If *length* is larger than the
    current size of the file, the file is extended to contain *length* bytes.  If
    *length* is ``0``, the maximum length of the map is the current size of the
    file, except that if the file is empty Windows raises an exception (you cannot
@@ -61,12 +64,12 @@ not update the underlying file.
    *offset* must be a multiple of the ALLOCATIONGRANULARITY.
 
 
-.. function:: mmap(fileno, length[, flags[, prot[, access[, offset]]]])
+.. class:: mmap(fileno, length[, flags[, prot[, access[, offset]]]])
    :noindex:
 
    **(Unix version)** Maps *length* bytes from the file specified by the file
    descriptor *fileno*, and returns a mmap object.  If *length* is ``0``, the
-   maximum length of the map will be the current size of the file when :func:`mmap`
+   maximum length of the map will be the current size of the file when :class:`mmap`
    is called.
 
    *flags* specifies the nature of the mapping. :const:`MAP_PRIVATE` creates a
@@ -87,7 +90,7 @@ not update the underlying file.
    be relative to the offset from the beginning of the file. *offset* defaults to 0.
    *offset* must be a multiple of the PAGESIZE or ALLOCATIONGRANULARITY.
    
-   This example shows a simple way of using :func:`mmap`::
+   This example shows a simple way of using :class:`mmap`::
 
       import mmap
 
diff --git a/Misc/NEWS b/Misc/NEWS
index e608478..2150ac1 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -368,6 +368,8 @@ Core and builtins
 
 Library
 -------
+- #1087741: mmap.mmap is now a class, not a factory function. It is also 
+  subclassable now.
 
 - #1269: fix a bug in pstats.add_callers() and add a unit test file for
   pstats.
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index e82014b..dfbc8fc 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -974,6 +974,9 @@ static PyBufferProcs mmap_as_buffer = {
 	(charbufferproc)mmap_buffer_getcharbuffer,
 };
 
+static PyObject *
+new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict);
+
 PyDoc_STRVAR(mmap_doc,
 "Windows: mmap(fileno, length[, tagname[, access[, offset]]])\n\
 \n\
@@ -999,7 +1002,7 @@ To map anonymous memory, pass -1 as the fileno (both versions).");
 
 
 static PyTypeObject mmap_object_type = {
-	PyVarObject_HEAD_INIT(0, 0) /* patched in module init */
+	PyVarObject_HEAD_INIT(NULL, 0)
 	"mmap.mmap",				/* tp_name */
 	sizeof(mmap_object),			/* tp_size */
 	0,					/* tp_itemsize */
@@ -1019,16 +1022,26 @@ static PyTypeObject mmap_object_type = {
 	PyObject_GenericGetAttr,		/*tp_getattro*/
 	0,					/*tp_setattro*/
 	&mmap_as_buffer,			/*tp_as_buffer*/
-	Py_TPFLAGS_HAVE_GETCHARBUFFER,		/*tp_flags*/
+	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GETCHARBUFFER,		/*tp_flags*/
 	mmap_doc,				/*tp_doc*/
 	0,					/* tp_traverse */
 	0,					/* tp_clear */
 	0,					/* tp_richcompare */
 	0,					/* tp_weaklistoffset */
-	0,					/* tp_iter */
-	0,					/* tp_iternext */
+	0,		                        /* tp_iter */
+	0,		                        /* tp_iternext */
 	mmap_object_methods,			/* tp_methods */
-
+	0,					/* tp_members */
+	0,					/* tp_getset */
+	0,					/* tp_base */
+	0,					/* tp_dict */
+	0,					/* tp_descr_get */
+	0,					/* tp_descr_set */
+	0,					/* tp_dictoffset */
+	0,                                      /* tp_init */
+	PyType_GenericAlloc,			/* tp_alloc */
+	new_mmap_object,			/* tp_new */
+	PyObject_Del,                           /* tp_free */
 };
 
 
@@ -1060,7 +1073,7 @@ _GetMapSize(PyObject *o, const char* param)
 
 #ifdef UNIX
 static PyObject *
-new_mmap_object(PyObject *self, PyObject *args, PyObject *kwdict)
+new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict)
 {
 #ifdef HAVE_FSTAT
 	struct stat st;
@@ -1128,7 +1141,7 @@ new_mmap_object(PyObject *self, PyObject *args, PyObject *kwdict)
 		}
 	}
 #endif
-	m_obj = PyObject_New(mmap_object, &mmap_object_type);
+	m_obj = (mmap_object *)type->tp_alloc(type, 0);
 	if (m_obj == NULL) {return NULL;}
 	m_obj->data = NULL;
 	m_obj->size = (size_t) map_size;
@@ -1182,7 +1195,7 @@ new_mmap_object(PyObject *self, PyObject *args, PyObject *kwdict)
 
 #ifdef MS_WINDOWS
 static PyObject *
-new_mmap_object(PyObject *self, PyObject *args, PyObject *kwdict)
+new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict)
 {
 	mmap_object *m_obj;
 	PyObject *map_size_obj = NULL, *offset_obj = NULL;
@@ -1250,7 +1263,7 @@ new_mmap_object(PyObject *self, PyObject *args, PyObject *kwdict)
 		lseek(fileno, 0, SEEK_SET);
 	}
 
-	m_obj = PyObject_New(mmap_object, &mmap_object_type);
+	m_obj = (mmap_object *)type->tp_alloc(type, 0);
 	if (m_obj == NULL)
 		return NULL;
 	/* Set every field to an invalid marker, so we can safely
@@ -1364,13 +1377,6 @@ new_mmap_object(PyObject *self, PyObject *args, PyObject *kwdict)
 }
 #endif /* MS_WINDOWS */
 
-/* List of functions exported by this module */
-static struct PyMethodDef mmap_functions[] = {
-	{"mmap",	(PyCFunction) new_mmap_object,
-	 METH_VARARGS|METH_KEYWORDS, mmap_doc},
-	{NULL,		NULL}	     /* Sentinel */
-};
-
 static void
 setint(PyObject *d, const char *name, long value)
 {
@@ -1381,14 +1387,14 @@ setint(PyObject *d, const char *name, long value)
 }
 
 PyMODINIT_FUNC
-	initmmap(void)
+initmmap(void)
 {
 	PyObject *dict, *module;
 
-	/* Patch the object type */
-	Py_TYPE(&mmap_object_type) = &PyType_Type;
+	if (PyType_Ready(&mmap_object_type) < 0)
+		return;
 
-	module = Py_InitModule("mmap", mmap_functions);
+	module = Py_InitModule("mmap", NULL);
 	if (module == NULL)
 		return;
 	dict = PyModule_GetDict(module);
@@ -1396,6 +1402,7 @@ PyMODINIT_FUNC
 		return;
 	mmap_module_error = PyExc_EnvironmentError;
 	PyDict_SetItemString(dict, "error", mmap_module_error);
+	PyDict_SetItemString(dict, "mmap", (PyObject*) &mmap_object_type);
 #ifdef PROT_EXEC
 	setint(dict, "PROT_EXEC", PROT_EXEC);
 #endif