Issue #20283: RE pattern methods now accept the string keyword parameters

as documented.  The pattern and source keyword parameters are left as
deprecated aliases.

Lib/test/test_re.py

@@ -1076,6 +1076,22 @@ class ReTests(unittest.TestCase):
         self.assertEqual(out.getvalue().splitlines(),
                          ['literal 102 ', 'literal 111 ', 'literal 111 '])
 
+    def test_keyword_parameters(self):
+        # Issue #20283: Accepting the string keyword parameter.
+        pat = re.compile(r'(ab)')
+        self.assertEqual(
+            pat.match(string='abracadabra', pos=7, endpos=10).span(), (7, 9))
+        self.assertEqual(
+            pat.search(string='abracadabra', pos=3, endpos=10).span(), (7, 9))
+        self.assertEqual(
+            pat.findall(string='abracadabra', pos=3, endpos=10), ['ab'])
+        self.assertEqual(
+            pat.split(string='abracadabra', maxsplit=1),
+            ['', 'ab', 'racadabra'])
+        self.assertEqual(
+            pat.scanner(string='abracadabra', pos=3, endpos=10).search().span(),
+            (7, 9))
+
 
 def run_re_tests():
     from test.re_tests import tests, SUCCEED, FAIL, SYNTAX_ERROR

Misc/NEWS

@@ -22,6 +22,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #20283: RE pattern methods now accept the string keyword parameters
+  as documented.  The pattern and source keyword parameters are left as
+  deprecated aliases.
+
 - Issue #20778: Fix modulefinder to work with bytecode-only modules.
 
 - Issue #20791: copy.copy() now doesn't make a copy when the input is

Modules/_sre.c

@@ -1876,18 +1876,46 @@ pattern_dealloc(PatternObject* self)
     PyObject_DEL(self);
 }
 
+static PyObject*
+fix_string_param(PyObject *string, PyObject *string2, const char *oldname)
+{
+    if (string2 != NULL) {
+        if (string != NULL) {
+            PyErr_Format(PyExc_TypeError,
+                         "Argument given by name ('%s') and position (1)",
+                         oldname);
+            return NULL;
+        }
+        if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+                             "The '%s' keyword parameter name is deprecated.  "
+                             "Use 'string' instead.", oldname) < 0)
+            return NULL;
+        return string2;
+    }
+    if (string == NULL) {
+        PyErr_SetString(PyExc_TypeError,
+                        "Required argument 'string' (pos 1) not found");
+        return NULL;
+    }
+    return string;
+}
+
 static PyObject*
 pattern_match(PatternObject* self, PyObject* args, PyObject* kw)
 {
     SRE_STATE state;
     int status;
 
-    PyObject* string;
+    PyObject *string = NULL, *string2 = NULL;
     Py_ssize_t start = 0;
     Py_ssize_t end = PY_SSIZE_T_MAX;
-    static char* kwlist[] = { "pattern", "pos", "endpos", NULL };
-    if (!PyArg_ParseTupleAndKeywords(args, kw, "O|nn:match", kwlist,
-                                     &string, &start, &end))
+    static char* kwlist[] = { "string", "pos", "endpos", "pattern", NULL };
+    if (!PyArg_ParseTupleAndKeywords(args, kw, "|Onn$O:match", kwlist,
+                                     &string, &start, &end, &string2))
+        return NULL;
+
+    string = fix_string_param(string, string2, "pattern");
+    if (!string)
         return NULL;
 
     string = state_init(&state, self, string, start, end);
@@ -1919,12 +1947,16 @@ pattern_search(PatternObject* self, PyObject* args, PyObject* kw)
     SRE_STATE state;
     int status;
 
-    PyObject* string;
+    PyObject *string = NULL, *string2 = NULL;
     Py_ssize_t start = 0;
     Py_ssize_t end = PY_SSIZE_T_MAX;
-    static char* kwlist[] = { "pattern", "pos", "endpos", NULL };
-    if (!PyArg_ParseTupleAndKeywords(args, kw, "O|nn:search", kwlist,
-                                     &string, &start, &end))
+    static char* kwlist[] = { "string", "pos", "endpos", "pattern", NULL };
+    if (!PyArg_ParseTupleAndKeywords(args, kw, "|Onn$O:search", kwlist,
+                                     &string, &start, &end, &string2))
+        return NULL;
+
+    string = fix_string_param(string, string2, "pattern");
+    if (!string)
         return NULL;
 
     string = state_init(&state, self, string, start, end);
@@ -2052,12 +2084,16 @@ pattern_findall(PatternObject* self, PyObject* args, PyObject* kw)
     int status;
     Py_ssize_t i, b, e;
 
-    PyObject* string;
+    PyObject *string = NULL, *string2 = NULL;
     Py_ssize_t start = 0;
     Py_ssize_t end = PY_SSIZE_T_MAX;
-    static char* kwlist[] = { "source", "pos", "endpos", NULL };
-    if (!PyArg_ParseTupleAndKeywords(args, kw, "O|nn:findall", kwlist,
-                                     &string, &start, &end))
+    static char* kwlist[] = { "string", "pos", "endpos", "source", NULL };
+    if (!PyArg_ParseTupleAndKeywords(args, kw, "|Onn$O:findall", kwlist,
+                                     &string, &start, &end, &string2))
+        return NULL;
+
+    string = fix_string_param(string, string2, "source");
+    if (!string)
         return NULL;
 
     string = state_init(&state, self, string, start, end);
@@ -2180,11 +2216,15 @@ pattern_split(PatternObject* self, PyObject* args, PyObject* kw)
     Py_ssize_t i;
     void* last;
 
-    PyObject* string;
+    PyObject *string = NULL, *string2 = NULL;
     Py_ssize_t maxsplit = 0;
-    static char* kwlist[] = { "source", "maxsplit", NULL };
-    if (!PyArg_ParseTupleAndKeywords(args, kw, "O|n:split", kwlist,
-                                     &string, &maxsplit))
+    static char* kwlist[] = { "string", "maxsplit", "source", NULL };
+    if (!PyArg_ParseTupleAndKeywords(args, kw, "|On$O:split", kwlist,
+                                     &string, &maxsplit, &string2))
+        return NULL;
+
+    string = fix_string_param(string, string2, "source");
+    if (!string)
         return NULL;
 
     string = state_init(&state, self, string, 0, PY_SSIZE_T_MAX);
@@ -3882,12 +3922,16 @@ pattern_scanner(PatternObject* pattern, PyObject* args, PyObject* kw)
 
     ScannerObject* self;
 
-    PyObject* string;
+    PyObject *string = NULL, *string2 = NULL;
     Py_ssize_t start = 0;
     Py_ssize_t end = PY_SSIZE_T_MAX;
-    static char* kwlist[] = { "source", "pos", "endpos", NULL };
-    if (!PyArg_ParseTupleAndKeywords(args, kw, "O|nn:scanner", kwlist,
-                                     &string, &start, &end))
+    static char* kwlist[] = { "string", "pos", "endpos", "source", NULL };
+    if (!PyArg_ParseTupleAndKeywords(args, kw, "|Onn$O:scanner", kwlist,
+                                     &string, &start, &end, &string2))
+        return NULL;
+
+    string = fix_string_param(string, string2, "source");
+    if (!string)
         return NULL;
 
     /* create scanner object */