Added a __deepcopy__() method to the Widget class in order to avoid a…

… number of easy-to-trigger problems when copying Widget subclasses. Subclasses which are intended to have extra mutable fields should override this method. Refs #5505.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@6450 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/newforms/widgets.py

@@ -7,7 +7,9 @@
 except NameError:
     from sets import Set as set   # Python 2.3 fallback
 
+import copy
 from itertools import chain
+
 from django.utils.datastructures import MultiValueDict
 from django.utils.html import escape
 from django.utils.translation import ugettext
@@ -32,6 +34,12 @@ def __init__(self, attrs=None):
         else:
             self.attrs = {}
 
+    def __deepcopy__(self, memo):
+        obj = copy.copy(self)
+        obj.attrs = self.attrs.copy()
+        memo[id(self)] = obj
+        return obj
+
     def render(self, name, value, attrs=None):
         """
         Returns this Widget rendered as HTML, as a Unicode string.