Add counting of source iterator lines to the reader object - handy for

user error messages (otherwise difficult to do without instrumenting
the source).

Lib/test/test_csv.py

@@ -242,7 +242,7 @@ class Test_Csv(unittest.TestCase):
         self._read_test(['1,",3,",5'], [['1', '"', '3', '"', '5']],
                         quoting=csv.QUOTE_NONE, escapechar='\\')
         # will this fail where locale uses comma for decimals?
-        self._read_test([',3,"5",7.3'], [['', 3, '5', 7.3]],
+        self._read_test([',3,"5",7.3, 9'], [['', 3, '5', 7.3, 9]],
                         quoting=csv.QUOTE_NONNUMERIC)
         self.assertRaises(ValueError, self._read_test, 
                           ['abc,3'], [[]],
@@ -267,6 +267,18 @@ class Test_Csv(unittest.TestCase):
         finally:
             csv.field_size_limit(limit)
 
+    def test_read_linenum(self):
+        r = csv.reader(['line,1', 'line,2', 'line,3'])
+        self.assertEqual(r.line_num, 0)
+        r.next()
+        self.assertEqual(r.line_num, 1)
+        r.next()
+        self.assertEqual(r.line_num, 2)
+        r.next()
+        self.assertEqual(r.line_num, 3)
+        self.assertRaises(StopIteration, r.next)
+        self.assertEqual(r.line_num, 3)
+
 class TestDialectRegistry(unittest.TestCase):
     def test_registry_badargs(self):
         self.assertRaises(TypeError, csv.list_dialects, None)

Misc/NEWS

@@ -66,6 +66,10 @@ Library
   + A new module method csv.field_size_limit() has been added that sets
     the parser field size limit (returning the former limit). The initial
     limit is 128kB.
+  + A line_num attribute has been added to the reader object, which tracks
+    the number of lines read from the source iterator. This is not
+    the same as the number of records returned, as records can span
+    multiple lines.
   + reader and writer objects were not being registered with the cyclic-GC.
     This has been fixed.
 

Modules/_csv.c

@@ -98,6 +98,7 @@ typedef struct {
 	int field_len;		/* length of current field */
 	int had_parse_error;	/* did we have a parse error? */
 	int numeric_field;	/* treat field as numeric */
+	unsigned long line_num;	/* Source-file line number */
 } ReaderObj;
 
 staticforward PyTypeObject Reader_Type;
@@ -734,6 +735,7 @@ parse_process_char(ReaderObj *self, char c)
 
 static struct PyMemberDef Reader_memberlist[] = {
 	{ "dialect", T_OBJECT, R_OFF(dialect), RO },
+	{ "line_num", T_ULONG, R_OFF(line_num), RO },
 	{ NULL }
 };
 
@@ -753,6 +755,7 @@ Reader_iternext(ReaderObj *self)
                                                     "newline inside string");
                         return NULL;
                 }
+		++self->line_num;
 
                 if (self->had_parse_error)
 			if (parse_reset(self) < 0) {
@@ -924,6 +927,7 @@ csv_reader(PyObject *module, PyObject *args, PyObject *keyword_args)
         self->input_iter = NULL;
 	self->field = NULL;
 	self->field_size = 0;
+	self->line_num = 0;
 
 	if (parse_reset(self) < 0) {
                 Py_DECREF(self);