This patch makes sure that the function name always appears in the error

message, and tries to make the messages more consistent and helpful when
the wrong number of arguments or duplicate keyword arguments are supplied.
Comes with more tests for test_extcall.py and and an update to an error
message in test/output/test_pyexpat.

Lib/test/output/test_extcall

@@ -9,9 +9,9 @@ test_extcall
 (1, 2, 3) {'b': 5, 'a': 4}
 (1, 2, 3, 4, 5) {'b': 7, 'a': 6}
 (1, 2, 3, 6, 7) {'y': 5, 'b': 9, 'x': 4, 'a': 8}
-TypeError: not enough arguments to g(); expected 1, got 0
-TypeError: not enough arguments to g(); expected 1, got 0
-TypeError: not enough arguments to g(); expected 1, got 0
+TypeError: g() takes at least 1 argument (0 given)
+TypeError: g() takes at least 1 argument (0 given)
+TypeError: g() takes at least 1 argument (0 given)
 1 () {}
 1 (2,) {}
 1 (2, 3) {}
@@ -20,14 +20,89 @@ TypeError: not enough arguments to g(); expected 1, got 0
 1 () {'d': 4, 'b': 2, 'c': 3, 'a': 1}
 {'b': 2, 'c': 3, 'a': 1}
 {'b': 2, 'c': 3, 'a': 1}
-keyword parameter 'x' redefined in call to g()
-keyword parameter 'b' redefined in function call
-keywords must be strings
+g() got multiple values for keyword argument 'x'
+g() got multiple values for keyword argument 'b'
+f() keywords must be strings
 h() got an unexpected keyword argument 'e'
-* argument must be a sequence
-** argument must be a dictionary
+h() argument after * must be a sequence
+h() argument after ** must be a dictionary
 3 512 1
 3
 3
-unbound method must be called with instance as first argument
-unbound method must be called with instance as first argument
+unbound method method() must be called with instance as first argument
+unbound method method() must be called with instance as first argument
+za () {} -> za() takes exactly 1 argument (0 given)
+za () {'a': 'aa'} -> ok za aa B D E V a
+za () {'d': 'dd'} -> za() got an unexpected keyword argument 'd'
+za () {'d': 'dd', 'a': 'aa'} -> za() got an unexpected keyword argument 'd'
+za () {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> za() got an unexpected keyword argument 'd'
+za (1, 2) {} -> za() takes exactly 1 argument (2 given)
+za (1, 2) {'a': 'aa'} -> za() takes exactly 1 non-keyword argument (2 given)
+za (1, 2) {'d': 'dd'} -> za() takes exactly 1 non-keyword argument (2 given)
+za (1, 2) {'d': 'dd', 'a': 'aa'} -> za() takes exactly 1 non-keyword argument (2 given)
+za (1, 2) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> za() takes exactly 1 non-keyword argument (2 given)
+za (1, 2, 3, 4, 5) {} -> za() takes exactly 1 argument (5 given)
+za (1, 2, 3, 4, 5) {'a': 'aa'} -> za() takes exactly 1 non-keyword argument (5 given)
+za (1, 2, 3, 4, 5) {'d': 'dd'} -> za() takes exactly 1 non-keyword argument (5 given)
+za (1, 2, 3, 4, 5) {'d': 'dd', 'a': 'aa'} -> za() takes exactly 1 non-keyword argument (5 given)
+za (1, 2, 3, 4, 5) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> za() takes exactly 1 non-keyword argument (5 given)
+zade () {} -> zade() takes at least 1 argument (0 given)
+zade () {'a': 'aa'} -> ok zade aa B d e V a
+zade () {'d': 'dd'} -> zade() takes at least 1 non-keyword argument (0 given)
+zade () {'d': 'dd', 'a': 'aa'} -> ok zade aa B dd e V d
+zade () {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zade() got an unexpected keyword argument 'b'
+zade (1, 2) {} -> ok zade 1 B 2 e V e
+zade (1, 2) {'a': 'aa'} -> zade() got multiple values for keyword argument 'a'
+zade (1, 2) {'d': 'dd'} -> zade() got multiple values for keyword argument 'd'
+zade (1, 2) {'d': 'dd', 'a': 'aa'} -> zade() got multiple values for keyword argument 'd'
+zade (1, 2) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zade() got multiple values for keyword argument 'd'
+zade (1, 2, 3, 4, 5) {} -> zade() takes at most 3 arguments (5 given)
+zade (1, 2, 3, 4, 5) {'a': 'aa'} -> zade() takes at most 3 non-keyword arguments (5 given)
+zade (1, 2, 3, 4, 5) {'d': 'dd'} -> zade() takes at most 3 non-keyword arguments (5 given)
+zade (1, 2, 3, 4, 5) {'d': 'dd', 'a': 'aa'} -> zade() takes at most 3 non-keyword arguments (5 given)
+zade (1, 2, 3, 4, 5) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zade() takes at most 3 non-keyword arguments (5 given)
+zabk () {} -> zabk() takes exactly 2 arguments (0 given)
+zabk () {'a': 'aa'} -> zabk() takes exactly 2 non-keyword arguments (1 given)
+zabk () {'d': 'dd'} -> zabk() takes exactly 2 non-keyword arguments (0 given)
+zabk () {'d': 'dd', 'a': 'aa'} -> zabk() takes exactly 2 non-keyword arguments (1 given)
+zabk () {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> ok zabk aa bb D E V {'d': 'dd', 'e': 'ee'}
+zabk (1, 2) {} -> ok zabk 1 2 D E V {}
+zabk (1, 2) {'a': 'aa'} -> zabk() got multiple values for keyword argument 'a'
+zabk (1, 2) {'d': 'dd'} -> ok zabk 1 2 D E V {'d': 'dd'}
+zabk (1, 2) {'d': 'dd', 'a': 'aa'} -> zabk() got multiple values for keyword argument 'a'
+zabk (1, 2) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zabk() got multiple values for keyword argument 'b'
+zabk (1, 2, 3, 4, 5) {} -> zabk() takes exactly 2 arguments (5 given)
+zabk (1, 2, 3, 4, 5) {'a': 'aa'} -> zabk() takes exactly 2 non-keyword arguments (5 given)
+zabk (1, 2, 3, 4, 5) {'d': 'dd'} -> zabk() takes exactly 2 non-keyword arguments (5 given)
+zabk (1, 2, 3, 4, 5) {'d': 'dd', 'a': 'aa'} -> zabk() takes exactly 2 non-keyword arguments (5 given)
+zabk (1, 2, 3, 4, 5) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zabk() takes exactly 2 non-keyword arguments (5 given)
+zabdv () {} -> zabdv() takes at least 2 arguments (0 given)
+zabdv () {'a': 'aa'} -> zabdv() takes at least 2 non-keyword arguments (1 given)
+zabdv () {'d': 'dd'} -> zabdv() takes at least 2 non-keyword arguments (0 given)
+zabdv () {'d': 'dd', 'a': 'aa'} -> zabdv() takes at least 2 non-keyword arguments (1 given)
+zabdv () {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zabdv() got an unexpected keyword argument 'e'
+zabdv (1, 2) {} -> ok zabdv 1 2 d E () e
+zabdv (1, 2) {'a': 'aa'} -> zabdv() got multiple values for keyword argument 'a'
+zabdv (1, 2) {'d': 'dd'} -> ok zabdv 1 2 dd E () d
+zabdv (1, 2) {'d': 'dd', 'a': 'aa'} -> zabdv() got multiple values for keyword argument 'a'
+zabdv (1, 2) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zabdv() got an unexpected keyword argument 'e'
+zabdv (1, 2, 3, 4, 5) {} -> ok zabdv 1 2 3 E (4, 5) e
+zabdv (1, 2, 3, 4, 5) {'a': 'aa'} -> zabdv() got multiple values for keyword argument 'a'
+zabdv (1, 2, 3, 4, 5) {'d': 'dd'} -> zabdv() got multiple values for keyword argument 'd'
+zabdv (1, 2, 3, 4, 5) {'d': 'dd', 'a': 'aa'} -> zabdv() got multiple values for keyword argument 'd'
+zabdv (1, 2, 3, 4, 5) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zabdv() got multiple values for keyword argument 'd'
+zabdevk () {} -> zabdevk() takes at least 2 arguments (0 given)
+zabdevk () {'a': 'aa'} -> zabdevk() takes at least 2 non-keyword arguments (1 given)
+zabdevk () {'d': 'dd'} -> zabdevk() takes at least 2 non-keyword arguments (0 given)
+zabdevk () {'d': 'dd', 'a': 'aa'} -> zabdevk() takes at least 2 non-keyword arguments (1 given)
+zabdevk () {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> ok zabdevk aa bb dd ee () {}
+zabdevk (1, 2) {} -> ok zabdevk 1 2 d e () {}
+zabdevk (1, 2) {'a': 'aa'} -> zabdevk() got multiple values for keyword argument 'a'
+zabdevk (1, 2) {'d': 'dd'} -> ok zabdevk 1 2 dd e () {}
+zabdevk (1, 2) {'d': 'dd', 'a': 'aa'} -> zabdevk() got multiple values for keyword argument 'a'
+zabdevk (1, 2) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zabdevk() got multiple values for keyword argument 'b'
+zabdevk (1, 2, 3, 4, 5) {} -> ok zabdevk 1 2 3 4 (5,) {}
+zabdevk (1, 2, 3, 4, 5) {'a': 'aa'} -> zabdevk() got multiple values for keyword argument 'a'
+zabdevk (1, 2, 3, 4, 5) {'d': 'dd'} -> zabdevk() got multiple values for keyword argument 'd'
+zabdevk (1, 2, 3, 4, 5) {'d': 'dd', 'a': 'aa'} -> zabdevk() got multiple values for keyword argument 'd'
+zabdevk (1, 2, 3, 4, 5) {'d': 'dd', 'e': 'ee', 'b': 'bb', 'a': 'aa'} -> zabdevk() got multiple values for keyword argument 'd'

Lib/test/output/test_pyexpat

@@ -97,7 +97,7 @@ End element:
 Testing constructor for proper handling of namespace_separator values:
 Legal values tested o.k.
 Caught expected TypeError:
-ParserCreate, argument 2: expected string or None, int found
+ParserCreate() argument 2 must be string or None, not int
 Caught expected ValueError:
 namespace_separator must be one character, omitted, or None
 Caught expected ValueError:

Lib/test/test_extcall.py

 from UserList import UserList
 from test_support import TestFailed
+import string
 
 def f(*a, **k):
     print a, k
@@ -172,3 +173,32 @@ except TypeError:
     pass
 else:
     raise TestFailed, 'expected TypeError; no exception raised'
+
+a, b, d, e, v, k = 'A', 'B', 'D', 'E', 'V', 'K'
+funcs = []
+maxargs = {}
+for args in ['', 'a', 'ab']:
+    for defargs in ['', 'd', 'de']:
+        for vararg in ['', 'v']:
+            for kwarg in ['', 'k']:
+                name = 'z' + args + defargs + vararg + kwarg
+                arglist = list(args) + map(
+                    lambda x: '%s="%s"' % (x, x), defargs)
+                if vararg: arglist.append('*' + vararg)
+                if kwarg: arglist.append('**' + kwarg)
+                decl = 'def %s(%s): print "ok %s", a, b, d, e, v, k' % (
+                    name, string.join(arglist, ', '), name)
+                exec(decl)
+                func = eval(name)
+                funcs.append(func)
+                maxargs[func] = len(args + defargs)
+
+for name in ['za', 'zade', 'zabk', 'zabdv', 'zabdevk']:
+    func = eval(name)
+    for args in [(), (1, 2), (1, 2, 3, 4, 5)]:
+        for kwargs in ['', 'a', 'd', 'ad', 'abde']:
+            kwdict = {}
+            for k in kwargs: kwdict[k] = k + k
+            print func.func_name, args, kwdict, '->',
+            try: apply(func, args, kwdict)
+            except TypeError, err: print err

Python/ceval.c

@@ -48,7 +48,7 @@ static PyObject *fast_function(PyObject *, PyObject ***, int, int, int);
 static PyObject *fast_cfunction(PyObject *, PyObject ***, int);
 static PyObject *do_call(PyObject *, PyObject ***, int, int);
 static PyObject *ext_do_call(PyObject *, PyObject ***, int, int, int);
-static PyObject *update_keyword_args(PyObject *, int, PyObject ***);
+static PyObject *update_keyword_args(PyObject *, int, PyObject ***, PyObject *);
 static PyObject *update_star_args(int, int, PyObject *, PyObject ***);
 static PyObject *load_args(PyObject ***, int);
 #define CALL_FLAG_VAR 1
@@ -451,10 +451,14 @@ eval_code2(PyCodeObject *co, PyObject *globals, PyObject *locals,
 		if (argcount > co->co_argcount) {
 			if (!(co->co_flags & CO_VARARGS)) {
 				PyErr_Format(PyExc_TypeError,
-				    "too many arguments to %s(); "
-				    "expected %d, got %d",
+				    "%.200s() takes %s %d "
+				    "%sargument%s (%d given)",
 				    PyString_AsString(co->co_name),
-				    co->co_argcount, argcount);
+				    defcount ? "at most" : "exactly",
+				    co->co_argcount,
+				    kwcount ? "non-keyword " : "",
+				    co->co_argcount == 1 ? "" : "s",
+				    argcount);
 				goto fail;
 			}
 			n = co->co_argcount;
@@ -480,8 +484,9 @@ eval_code2(PyCodeObject *co, PyObject *globals, PyObject *locals,
 			PyObject *value = kws[2*i + 1];
 			int j;
 			if (keyword == NULL || !PyString_Check(keyword)) {
-				PyErr_SetString(PyExc_TypeError,
-						"keywords must be strings");
+				PyErr_Format(PyExc_TypeError,
+				    "%.200s() keywords must be strings",
+				    PyString_AsString(co->co_name));
 				goto fail;
 			}
 			/* XXX slow -- speed up using dictionary? */
@@ -508,10 +513,11 @@ eval_code2(PyCodeObject *co, PyObject *globals, PyObject *locals,
 			else {
 				if (GETLOCAL(j) != NULL) {
 					PyErr_Format(PyExc_TypeError, 
-					     "keyword parameter '%.400s' "
-					     "redefined in call to %.200s()",
-					     PyString_AsString(keyword),
-					     PyString_AsString(co->co_name));
+					     "%.200s() got multiple "
+					     "values for keyword "
+					     "argument '%.400s'",
+					     PyString_AsString(co->co_name),
+					     PyString_AsString(keyword));
 					goto fail;
 				}
 				Py_INCREF(value);
@@ -523,10 +529,14 @@ eval_code2(PyCodeObject *co, PyObject *globals, PyObject *locals,
 			for (i = argcount; i < m; i++) {
 				if (GETLOCAL(i) == NULL) {
 					PyErr_Format(PyExc_TypeError,
-					    "not enough arguments to "
-					    "%.200s(); expected %d, got %d",
+					    "%.200s() takes %s %d "
+					    "%sargument%s (%d given)",
 					    PyString_AsString(co->co_name),
-					    m, i);
+					    ((co->co_flags & CO_VARARGS) ||
+					     defcount) ? "at least"
+						       : "exactly",
+					    m, kwcount ? "non-keyword " : "",
+					    m == 1 ? "" : "s", i);
 					goto fail;
 				}
 			}
@@ -546,8 +556,9 @@ eval_code2(PyCodeObject *co, PyObject *globals, PyObject *locals,
 	else {
 		if (argcount > 0 || kwcount > 0) {
 			PyErr_Format(PyExc_TypeError,
-				     "%.200s() expected no arguments",
-				     PyString_AsString(co->co_name));
+				     "%.200s() takes no arguments (%d given)",
+				     PyString_AsString(co->co_name),
+				     argcount + kwcount);
 			goto fail;
 		}
 	}
@@ -2669,8 +2680,12 @@ call_method(PyObject *func, PyObject *arg, PyObject *kw)
 		    && PyClass_IsSubclass((PyObject *)
 				  (((PyInstanceObject *)self)->in_class),
 					  class))) {
-		PyErr_SetString(PyExc_TypeError,
-	"unbound method must be called with instance as first argument");
+                PyObject* fn = ((PyFunctionObject*) func)->func_name;
+		PyErr_Format(PyExc_TypeError,
+                             "unbound method %s%smust be "
+                             "called with instance as first argument",
+                             fn ? PyString_AsString(fn) : "",
+                             fn ? "() " : "");
 			return NULL;
 		}
 		Py_INCREF(arg);
@@ -2793,7 +2808,8 @@ fast_function(PyObject *func, PyObject ***pp_stack, int n, int na, int nk)
 }
 
 static PyObject *
-update_keyword_args(PyObject *orig_kwdict, int nk, PyObject ***pp_stack)
+update_keyword_args(PyObject *orig_kwdict, int nk, PyObject ***pp_stack,
+                    PyObject *func)
 {
 	PyObject *kwdict = NULL;
 	if (orig_kwdict == NULL)
@@ -2809,10 +2825,12 @@ update_keyword_args(PyObject *orig_kwdict, int nk, PyObject ***pp_stack)
 		PyObject *value = EXT_POP(*pp_stack);
 		PyObject *key = EXT_POP(*pp_stack);
 		if (PyDict_GetItem(kwdict, key) != NULL) {
+                        PyObject* fn = ((PyFunctionObject*) func)->func_name;
                         PyErr_Format(PyExc_TypeError, 
-				     "keyword parameter '%.400s' "
-				     "redefined in function call",
-				     PyString_AsString(key));
+                                     "%.200s%s got multiple values "
+                                     "for keyword argument '%.400s'",
+                                     fn ? PyString_AsString(fn) : "function",
+                                     fn ? "()" : "", PyString_AsString(key));
 			Py_DECREF(key);
 			Py_DECREF(value);
 			Py_DECREF(kwdict);
@@ -2877,7 +2895,7 @@ do_call(PyObject *func, PyObject ***pp_stack, int na, int nk)
 	PyObject *result = NULL;
 
 	if (nk > 0) {
-		kwdict = update_keyword_args(NULL, nk, pp_stack);
+		kwdict = update_keyword_args(NULL, nk, pp_stack, func);
 		if (kwdict == NULL)
 			goto call_fail;
 	}
@@ -2903,8 +2921,11 @@ ext_do_call(PyObject *func, PyObject ***pp_stack, int flags, int na, int nk)
 	if (flags & CALL_FLAG_KW) {
 		kwdict = EXT_POP(*pp_stack);
 		if (!(kwdict && PyDict_Check(kwdict))) {
-			PyErr_SetString(PyExc_TypeError,
-					"** argument must be a dictionary");
+                        PyObject* fn = ((PyFunctionObject*) func)->func_name;
+			PyErr_Format(PyExc_TypeError,
+                            "%s%s argument after ** must be a dictionary",
+                            fn ? PyString_AsString(fn) : "function",
+                            fn ? "()" : "");
 			goto ext_call_fail;
 		}
 	}
@@ -2915,8 +2936,12 @@ ext_do_call(PyObject *func, PyObject ***pp_stack, int flags, int na, int nk)
 			t = PySequence_Tuple(stararg);
 			if (t == NULL) {
 			    if (PyErr_ExceptionMatches(PyExc_TypeError)) {
-				PyErr_SetString(PyExc_TypeError,
-					"* argument must be a sequence");
+                                PyObject* fn =
+                                    ((PyFunctionObject*) func)->func_name;
+				PyErr_Format(PyExc_TypeError,
+                                    "%s%s argument after * must be a sequence",
+                                    fn ? PyString_AsString(fn) : "function",
+                                    fn ? "()" : "");
 			    }
 				goto ext_call_fail;
 			}
@@ -2926,7 +2951,7 @@ ext_do_call(PyObject *func, PyObject ***pp_stack, int flags, int na, int nk)
 		nstar = PyTuple_GET_SIZE(stararg);
 	}
 	if (nk > 0) {
-		kwdict = update_keyword_args(kwdict, nk, pp_stack);
+		kwdict = update_keyword_args(kwdict, nk, pp_stack, func);
 		if (kwdict == NULL)
 			goto ext_call_fail;
 	}

Python/getargs.c

@@ -130,16 +130,18 @@ vgetargs1(PyObject *args, char *format, va_list *p_va, int compat)
 		if (max == 0) {
 			if (args == NULL)
 				return 1;
-			sprintf(msgbuf, "%s requires no arguments",
-				fname==NULL ? "function" : fname);
+			sprintf(msgbuf, "%s%s takes no arguments",
+				fname==NULL ? "function" : fname,
+				fname==NULL ? "" : "()");
 			PyErr_SetString(PyExc_TypeError, msgbuf);
 			return 0;
 		}
 		else if (min == 1 && max == 1) {
 			if (args == NULL) {
 				sprintf(msgbuf,
-					"%s requires at least one argument",
-					fname==NULL ? "function" : fname);
+					"%s%s takes at least one argument",
+					fname==NULL ? "function" : fname,
+					fname==NULL ? "" : "()");
 				PyErr_SetString(PyExc_TypeError, msgbuf);
 				return 0;
 			}
@@ -167,8 +169,9 @@ vgetargs1(PyObject *args, char *format, va_list *p_va, int compat)
 	if (len < min || max < len) {
 		if (message == NULL) {
 			sprintf(msgbuf,
-				"%s requires %s %d argument%s; %d given",
+				"%s%s takes %s %d argument%s (%d given)",
 				fname==NULL ? "function" : fname,
+				fname==NULL ? "" : "()",
 				min==max ? "exactly"
 				         : len < min ? "at least" : "at most",
 				len < min ? min : max,
@@ -213,13 +216,12 @@ seterror(int iarg, char *msg, int *levels, char *fname, char *message)
 
 	if (PyErr_Occurred())
 		return;
-	if (iarg == 0 && message == NULL)
-		message = msg;
 	else if (message == NULL) {
 		if (fname != NULL) {
-			sprintf(p, "%s, ", fname);
+			sprintf(p, "%s() ", fname);
 			p += strlen(p);
 		}
+		if (iarg != 0) {
 			sprintf(p, "argument %d", iarg);
 			i = 0;
 			p += strlen(p);
@@ -228,7 +230,12 @@ seterror(int iarg, char *msg, int *levels, char *fname, char *message)
 				p += strlen(p);
 				i++;
 			}
-		sprintf(p, ": expected %s found", msg);
+		}
+		else {
+			sprintf(p, "argument");
+			p += strlen(p);
+		}
+		sprintf(p, " %s", msg);
 		message = buf;
 	}
 	PyErr_SetString(PyExc_TypeError, message);
@@ -247,10 +254,9 @@ seterror(int iarg, char *msg, int *levels, char *fname, char *message)
       *p_va is undefined,
       *levels is a 0-terminated list of item numbers,
       *msgbuf contains an error message, whose format is:
-         "<typename1>, <typename2>", where:
+         "must be <typename1>, not <typename2>", where:
             <typename1> is the name of the expected type, and
             <typename2> is the name of the actual type,
-         (so you can surround it by "expected ... found"),
       and msgbuf is returned.
 */
 
@@ -281,10 +287,11 @@ converttuple(PyObject *arg, char **p_format, va_list *p_va, int *levels,
 			n++;
 	}
 	
-	if (!PySequence_Check(arg)) {
+	if (!PySequence_Check(arg) || PyString_Check(arg)) {
 		levels[0] = 0;
 		sprintf(msgbuf,
-			toplevel ? "%d arguments, %s" : "%d-sequence, %s",
+			toplevel ? "expected %d arguments, not %s" :
+				   "must be %d-item sequence, not %s",
 			n, arg == Py_None ? "None" : arg->ob_type->tp_name);
 		return msgbuf;
 	}
@@ -292,7 +299,8 @@ converttuple(PyObject *arg, char **p_format, va_list *p_va, int *levels,
 	if ((i = PySequence_Size(arg)) != n) {
 		levels[0] = 0;
 		sprintf(msgbuf,
-		    toplevel ? "%d arguments, %d" : "%d-sequence, %d-sequence",
+			toplevel ? "expected %d arguments, not %d" :
+				   "must be sequence of length %d, not %d",
 			n, i);
 		return msgbuf;
 	}
@@ -343,14 +351,14 @@ convertitem(PyObject *arg, char **p_format, va_list *p_va, int *levels,
 
 
 /* Convert a non-tuple argument.  Adds to convertsimple1 functionality
-   by appending ", <actual argument type>" to error message. */
+   by formatting messages as "must be <desired type>, not <actual type>". */
 
 static char *
 convertsimple(PyObject *arg, char **p_format, va_list *p_va, char *msgbuf)
 {
 	char *msg = convertsimple1(arg, p_format, p_va);
 	if (msg != NULL) {
-		sprintf(msgbuf, "%.50s, %.50s", msg,
+		sprintf(msgbuf, "must be %.50s, not %.50s", msg,
 			arg == Py_None ? "None" : arg->ob_type->tp_name);
 		msg = msgbuf;
 	}
@@ -1063,8 +1071,9 @@ vgetargskeywords(PyObject *args, PyObject *keywords, char *format,
 	if (len < min || max < len) {
 		if (message == NULL) {
 			sprintf(msgbuf,
-				"%s requires %s %d argument%s; %d given",
+				"%s%s takes %s %d argument%s (%d given)",
 				fname==NULL ? "function" : fname,
+				fname==NULL ? "" : "()",
 				min==max ? "exactly"
 				         : len < min ? "at least" : "at most",
 				len < min ? min : max,