Issue #20294: Argument Clinic now supports argument parsing for __new__ and

__init__ functions.

Doc/howto/clinic.rst

@@ -784,8 +784,8 @@ Argument Clinic converters.  On the left is the legacy converter,
 on the right is the text you'd replace it with.
 
 =========   =================================================================================
-``'B'``     ``byte(bitwise=True)``
-``'b'``     ``byte``
+``'B'``     ``unsigned_char(bitwise=True)``
+``'b'``     ``unsigned_char``
 ``'c'``     ``char``
 ``'C'``     ``int(types='str')``
 ``'d'``     ``double``
@@ -1275,6 +1275,25 @@ any arguments.
 You can still use a self converter, a return converter, and specify
 a ``type`` argument to the object converter for ``METH_O``.
 
+tp_new and tp_init functions
+----------------------------------------------
+
+You can convert ``tp_new`` and ``tp_init``
+functions.  Just name them ``__new__`` or
+``__init__`` as appropriate.  Notes:
+
+* The function name generated for ``__new__`` doesn't end in ``__new__``
+  like it would by default.  It's just the name of the class, converted
+  into a valid C identifier.
+
+* No ``PyMethodDef`` ``#define`` is generated for these functions.
+
+* ``__init__`` functions return ``int``, not ``PyObject *``.
+
+* Argument Clinic supports any signature for these functions, even though
+  the parsing function is required to always take ``args`` and ``kwargs``
+  objects.
+
 The #ifdef trick
 ----------------------------------------------
 

Include/modsupport.h

@@ -36,6 +36,7 @@ PyAPI_FUNC(PyObject *) _Py_BuildValue_SizeT(const char *, ...);
 #endif
 #ifndef Py_LIMITED_API
 PyAPI_FUNC(int) _PyArg_NoKeywords(const char *funcname, PyObject *kw);
+PyAPI_FUNC(int) _PyArg_NoPositional(const char *funcname, PyObject *args);
 
 PyAPI_FUNC(int) PyArg_VaParse(PyObject *, const char *, va_list);
 PyAPI_FUNC(int) PyArg_VaParseTupleAndKeywords(PyObject *, PyObject *,

Misc/NEWS

@@ -101,6 +101,9 @@ Tests
 Tools/Demos
 -----------
 
+- Issue #20294: Argument Clinic now supports argument parsing for __new__ and
+  __init__ functions.
+
 - Issue #20299: Argument Clinic custom converters may now change the default
   value of c_default and py_default with a class member.
 

Modules/_pickle.c

@@ -4064,13 +4064,13 @@ PyDoc_STRVAR(_pickle_Pickler___init____doc__,
 "to map the new Python 3 names to the old module names used in Python\n"
 "2, so that the pickle data stream is readable with Python 2.");
 
-static PyObject *
+static int
 _pickle_Pickler___init___impl(PicklerObject *self, PyObject *file, PyObject *protocol, int fix_imports);
 
-static PyObject *
+static int
 _pickle_Pickler___init__(PyObject *self, PyObject *args, PyObject *kwargs)
 {
-    PyObject *return_value = NULL;
+    int return_value = -1;
     static char *_keywords[] = {"file", "protocol", "fix_imports", NULL};
     PyObject *file;
     PyObject *protocol = NULL;
@@ -4086,9 +4086,9 @@ exit:
     return return_value;
 }
 
-static PyObject *
+static int
 _pickle_Pickler___init___impl(PicklerObject *self, PyObject *file, PyObject *protocol, int fix_imports)
-/*[clinic end generated code: checksum=defa3d9e9f8b51fb257d4fdfca99db503db0e6df]*/
+/*[clinic end generated code: checksum=10c8ea05194d08108471163d8202cf5e12975544]*/
 {
     _Py_IDENTIFIER(persistent_id);
     _Py_IDENTIFIER(dispatch_table);
@@ -4098,16 +4098,16 @@ _pickle_Pickler___init___impl(PicklerObject *self, PyObject *file, PyObject *pro
         (void)Pickler_clear(self);
 
     if (_Pickler_SetProtocol(self, protocol, fix_imports) < 0)
-        return NULL;
+        return -1;
 
     if (_Pickler_SetOutputStream(self, file) < 0)
-        return NULL;
+        return -1;
 
     /* memo and output_buffer may have already been created in _Pickler_New */
     if (self->memo == NULL) {
         self->memo = PyMemoTable_New();
         if (self->memo == NULL)
-            return NULL;
+            return -1;
     }
     self->output_len = 0;
     if (self->output_buffer == NULL) {
@@ -4115,7 +4115,7 @@ _pickle_Pickler___init___impl(PicklerObject *self, PyObject *file, PyObject *pro
         self->output_buffer = PyBytes_FromStringAndSize(NULL,
                                                         self->max_output_len);
         if (self->output_buffer == NULL)
-            return NULL;
+            return -1;
     }
 
     self->fast = 0;
@@ -4126,31 +4126,20 @@ _pickle_Pickler___init___impl(PicklerObject *self, PyObject *file, PyObject *pro
         self->pers_func = _PyObject_GetAttrId((PyObject *)self,
                                               &PyId_persistent_id);
         if (self->pers_func == NULL)
-            return NULL;
+            return -1;
     }
     self->dispatch_table = NULL;
     if (_PyObject_HasAttrId((PyObject *)self, &PyId_dispatch_table)) {
         self->dispatch_table = _PyObject_GetAttrId((PyObject *)self,
                                                    &PyId_dispatch_table);
         if (self->dispatch_table == NULL)
-            return NULL;
+            return -1;
     }
 
-    Py_RETURN_NONE;
-}
-
-/* Wrap the Clinic generated signature to slot it in tp_init. */
-static int
-Pickler_init(PyObject *self, PyObject *args, PyObject *kwargs)
-{
-    PyObject *result = _pickle_Pickler___init__(self, args, kwargs);
-    if (result == NULL) {
-        return -1;
-    }
-    Py_DECREF(result);
     return 0;
 }
 
+
 /* Define a proxy object for the Pickler's internal memo object. This is to
  * avoid breaking code like:
  *  pickler.memo.clear()
@@ -4543,7 +4532,7 @@ static PyTypeObject Pickler_Type = {
     0,                                  /*tp_descr_get*/
     0,                                  /*tp_descr_set*/
     0,                                  /*tp_dictoffset*/
-    Pickler_init,                       /*tp_init*/
+    _pickle_Pickler___init__,           /*tp_init*/
     PyType_GenericAlloc,                /*tp_alloc*/
     PyType_GenericNew,                  /*tp_new*/
     PyObject_GC_Del,                    /*tp_free*/
@@ -6614,13 +6603,13 @@ PyDoc_STRVAR(_pickle_Unpickler___init____doc__,
 "respectively.  The *encoding* can be \'bytes\' to read these 8-bit\n"
 "string instances as bytes objects.");
 
-static PyObject *
+static int
 _pickle_Unpickler___init___impl(UnpicklerObject *self, PyObject *file, int fix_imports, const char *encoding, const char *errors);
 
-static PyObject *
+static int
 _pickle_Unpickler___init__(PyObject *self, PyObject *args, PyObject *kwargs)
 {
-    PyObject *return_value = NULL;
+    int return_value = -1;
     static char *_keywords[] = {"file", "fix_imports", "encoding", "errors", NULL};
     PyObject *file;
     int fix_imports = 1;
@@ -6637,9 +6626,9 @@ exit:
     return return_value;
 }
 
-static PyObject *
+static int
 _pickle_Unpickler___init___impl(UnpicklerObject *self, PyObject *file, int fix_imports, const char *encoding, const char *errors)
-/*[clinic end generated code: checksum=26c1d4a06841a8e51d29a0c244ba7f4607ff358a]*/
+/*[clinic end generated code: checksum=6936e9188104e45b1b15e1c11fe77b3965409471]*/
 {
     _Py_IDENTIFIER(persistent_load);
 
@@ -6648,20 +6637,20 @@ _pickle_Unpickler___init___impl(UnpicklerObject *self, PyObject *file, int fix_i
         (void)Unpickler_clear(self);
 
     if (_Unpickler_SetInputStream(self, file) < 0)
-        return NULL;
+        return -1;
 
     if (_Unpickler_SetInputEncoding(self, encoding, errors) < 0)
-        return NULL;
+        return -1;
 
     self->fix_imports = fix_imports;
     if (self->fix_imports == -1)
-        return NULL;
+        return -1;
 
     if (_PyObject_HasAttrId((PyObject *)self, &PyId_persistent_load)) {
         self->pers_func = _PyObject_GetAttrId((PyObject *)self,
                                               &PyId_persistent_load);
         if (self->pers_func == NULL)
-            return NULL;
+            return 1;
     }
     else {
         self->pers_func = NULL;
@@ -6669,30 +6658,19 @@ _pickle_Unpickler___init___impl(UnpicklerObject *self, PyObject *file, int fix_i
 
     self->stack = (Pdata *)Pdata_New();
     if (self->stack == NULL)
-        return NULL;
+        return 1;
 
     self->memo_size = 32;
     self->memo = _Unpickler_NewMemo(self->memo_size);
     if (self->memo == NULL)
-        return NULL;
+        return -1;
 
     self->proto = 0;
 
-    Py_RETURN_NONE;
-}
-
-/* Wrap the Clinic generated signature to slot it in tp_init. */
-static int
-Unpickler_init(PyObject *self, PyObject *args, PyObject *kwargs)
-{
-    PyObject *result = _pickle_Unpickler___init__(self, args, kwargs);
-    if (result == NULL) {
-        return -1;
-    }
-    Py_DECREF(result);
     return 0;
 }
 
+
 /* Define a proxy object for the Unpickler's internal memo object. This is to
  * avoid breaking code like:
  *  unpickler.memo.clear()
@@ -7096,7 +7074,7 @@ static PyTypeObject Unpickler_Type = {
     0,                                  /*tp_descr_get*/
     0,                                  /*tp_descr_set*/
     0,                                  /*tp_dictoffset*/
-    Unpickler_init,                     /*tp_init*/
+    _pickle_Unpickler___init__,         /*tp_init*/
     PyType_GenericAlloc,                /*tp_alloc*/
     PyType_GenericNew,                  /*tp_new*/
     PyObject_GC_Del,                    /*tp_free*/

Python/getargs.c

@@ -1805,7 +1805,7 @@ PyArg_UnpackTuple(PyObject *args, const char *name, Py_ssize_t min, Py_ssize_t m
 
 /* For type constructors that don't take keyword args
  *
- * Sets a TypeError and returns 0 if the kwds dict is
+ * Sets a TypeError and returns 0 if the args/kwargs is
  * not empty, returns 1 otherwise
  */
 int
@@ -1824,6 +1824,25 @@ _PyArg_NoKeywords(const char *funcname, PyObject *kw)
                     funcname);
     return 0;
 }
+
+
+int
+_PyArg_NoPositional(const char *funcname, PyObject *args)
+{
+    if (args == NULL)
+        return 1;
+    if (!PyTuple_CheckExact(args)) {
+        PyErr_BadInternalCall();
+        return 0;
+    }
+    if (PyTuple_GET_SIZE(args) == 0)
+        return 1;
+
+    PyErr_Format(PyExc_TypeError, "%s does not take positional arguments",
+                    funcname);
+    return 0;
+}
+
 #ifdef __cplusplus
 };
 #endif