PEP 227 implementation

A cell contains a reference to a single PyObject.  It could be
implemented as a mutable, one-element sequence, but the separate type
has less overhead.

diff --git a/Include/Python.h b/Include/Python.h
index 308655250de1e4cd7df842ab858cd28dab2a1f8d..b771c8cf702ef2644061c01254f6c5bc0d3d5dbf 100644 (file)
--- a/Include/Python.h
+++ b/Include/Python.h
@@ -81,6 +81,7 @@
 #include "cobject.h"
 #include "traceback.h"
 #include "sliceobject.h"
+#include "cellobject.h"
 
 #include "codecs.h"
 #include "pyerrors.h"

diff --git a/Include/cellobject.h b/Include/cellobject.h
new file mode 100644 (file)
index 0000000..cc4a159
--- /dev/null
+++ b/Include/cellobject.h
@@ -0,0 +1,28 @@
+/* Cell object interface */
+
+#ifndef Py_CELLOBJECT_H
+#define Py_CELLOBJECT_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct {
+       PyObject_VAR_HEAD
+       PyObject *ob_ref;
+} PyCellObject;
+
+extern DL_IMPORT(PyTypeObject) PyCell_Type;
+
+#define PyCell_Check(op) ((op)->ob_type == &PyCell_Type)
+
+extern DL_IMPORT(PyObject *) PyCell_New(PyObject *);
+extern DL_IMPORT(PyObject *) PyCell_Get(PyObject *);
+extern DL_IMPORT(int) PyCell_Set(PyObject *, PyObject *);
+
+#define PyCell_GET(op) (((PyCellObject *)(op))->ob_ref)
+#define PyCell_SET(op, v) (((PyCellObject *)(op))->ob_ref = v)
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_TUPLEOBJECT_H */

diff --git a/Makefile.pre.in b/Makefile.pre.in
index cd5436ff7bf52af271cac41176913232c4a9de1d..ce54e444bf6da3a0be17e2821c6b5bda4b66f5ff 100644 (file)
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -236,6 +236,7 @@ PYTHON_OBJS=        \
 OBJECT_OBJS=   \
                Objects/abstract.o \
                Objects/bufferobject.o \
+               Objects/cellobject.o \
                Objects/classobject.o \
                Objects/cobject.o \
                Objects/complexobject.o \

diff --git a/Objects/cellobject.c b/Objects/cellobject.c
new file mode 100644 (file)
index 0000000..d9ecfd7
--- /dev/null
+++ b/Objects/cellobject.c
@@ -0,0 +1,115 @@
+/* Cell object implementation */
+
+#include "Python.h"
+
+PyObject *
+PyCell_New(PyObject *obj)
+{
+       PyCellObject *op;
+
+       op = (PyCellObject *)PyObject_New(PyCellObject, &PyCell_Type);
+       op->ob_ref = obj;
+       Py_XINCREF(obj);
+
+       PyObject_GC_Init(op);
+       return (PyObject *)op;
+}
+
+PyObject *
+PyCell_Get(PyObject *op)
+{
+       if (!PyCell_Check(op)) {
+               PyErr_BadInternalCall();
+               return NULL;
+       }
+       Py_XINCREF(((PyCellObject*)op)->ob_ref);
+       return PyCell_GET(op);
+}
+
+int
+PyCell_Set(PyObject *op, PyObject *obj)
+{
+       if (!PyCell_Check(op)) {
+               PyErr_BadInternalCall();
+               return -1;
+       }
+       Py_XDECREF(((PyCellObject*)op)->ob_ref);
+       Py_XINCREF(obj);
+       PyCell_SET(op, obj);
+       return 0;
+}
+
+static void
+cell_dealloc(PyCellObject *op)
+{
+       PyObject_GC_Fini(op);
+       Py_XDECREF(op->ob_ref);
+       PyObject_Del(op);
+}
+
+static int
+cell_compare(PyCellObject *a, PyCellObject *b)
+{
+       if (a->ob_ref == NULL) {
+               if (b->ob_ref == NULL)
+                       return 0;
+               return -1;
+       } else if (b->ob_ref == NULL)
+               return 1;
+       return PyObject_Compare(a->ob_ref, b->ob_ref);
+}
+
+static PyObject *
+cell_repr(PyCellObject *op)
+{
+       char buf[256];
+
+       if (op->ob_ref == NULL)
+               sprintf(buf, "<cell at %p: empty>", op);
+       else
+               sprintf(buf, "<cell at %p: %.80s object at %p>",
+                       op, op->ob_ref->ob_type->tp_name, op->ob_ref);
+       return PyString_FromString(buf);
+}
+
+static int
+cell_traverse(PyCellObject *op, visitproc visit, void *arg)
+{
+       if (op->ob_ref)
+               return visit(op->ob_ref, arg);
+       return 0;
+}
+
+static int
+cell_clear(PyCellObject *op)
+{
+       op->ob_ref = NULL;
+       return 0;
+}
+
+PyTypeObject PyCell_Type = {
+       PyObject_HEAD_INIT(&PyType_Type)
+       0,
+       "cell",
+       sizeof(PyCellObject) + PyGC_HEAD_SIZE,
+       0,
+       (destructor)cell_dealloc,               /* tp_dealloc */
+       0,                                      /* tp_print */
+       0,                                      /* tp_getattr */
+       0,                                      /* tp_setattr */
+       (cmpfunc)cell_compare,                  /* tp_compare */
+       (reprfunc)cell_repr,                    /* tp_repr */
+       0,                                      /* tp_as_number */
+       0,                                      /* tp_as_sequence */
+       0,                                      /* tp_as_mapping */
+       0,                                      /* tp_hash */
+       0,                                      /* tp_call */
+       0,                                      /* tp_str */
+       0,                                      /* tp_getattro */
+       0,                                      /* tp_setattro */
+       0,                                      /* tp_as_buffer */
+       Py_TPFLAGS_DEFAULT | Py_TPFLAGS_GC,     /* tp_flags */
+       0,                                      /* tp_doc */
+       (traverseproc)cell_traverse,            /* tp_traverse */
+       (inquiry)cell_clear,                    /* tp_clear */
+};