Merged revisions 65605 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r65605 | skip.montanaro | 2008-08-08 17:52:51 -0500 (Fri, 08 Aug 2008) | 1 line

  accept issue 3436
........

1 files changed, 18 insertions, 4 deletions

diff --git a/Lib/csv.py b/Lib/csv.py
index 09f4cf4..e0558c7 100644
--- a/Lib/csv.py
+++ b/Lib/csv.py
@@ -68,7 +68,7 @@ register_dialect("excel-tab", excel_tab)
 class DictReader:
     def __init__(self, f, fieldnames=None, restkey=None, restval=None,
                  dialect="excel", *args, **kwds):
-        self.fieldnames = fieldnames    # list of keys for the dict
+        self._fieldnames = fieldnames   # list of keys for the dict
         self.restkey = restkey          # key to catch long rows
         self.restval = restval          # default value for short rows
         self.reader = reader(f, dialect, *args, **kwds)
@@ -78,11 +78,25 @@ class DictReader:
     def __iter__(self):
         return self
 
+    @property
+    def fieldnames(self):
+        if self._fieldnames is None:
+            try:
+                self._fieldnames = next(self.reader)
+            except StopIteration:
+                pass
+        self.line_num = self.reader.line_num
+        return self._fieldnames
+
+    @fieldnames.setter
+    def fieldnames(self, value):
+        self._fieldnames = value
+
     def __next__(self):
+        if self.line_num == 0:
+            # Used only for its side effect.
+            self.fieldnames
         row = next(self.reader)
-        if self.fieldnames is None:
-            self.fieldnames = row
-            row = next(self.reader)
         self.line_num = self.reader.line_num
 
         # unlike the basic reader, we prefer not to return blanks,