fixes #753 - ValidationError and CriticalValidationError now accept b…

…oth strings and promises from gettext_lazy

git-svn-id: http://code.djangoproject.com/svn/django/trunk@1328 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/validators.py

@@ -27,14 +27,15 @@
 
 from django.conf.settings import JING_PATH
 from django.utils.translation import gettext_lazy, ngettext
+from django.utils.functional import Promise
 
 class ValidationError(Exception):
     def __init__(self, message):
         "ValidationError can be passed a string or a list."
         if isinstance(message, list):
             self.messages = message
         else:
-            assert isinstance(message, basestring), ("%s should be a string" % repr(message))
+            assert isinstance(message, (basestring, Promise)), ("%s should be a string" % repr(message))
             self.messages = [message]
     def __str__(self):
         # This is needed because, without a __str__(), printing an exception
@@ -49,7 +50,7 @@ def __init__(self, message):
         if isinstance(message, list):
             self.messages = message
         else:
-            assert isinstance(message, basestring), ("'%s' should be a string" % message)
+            assert isinstance(message, (basestring, Promise)), ("'%s' should be a string" % message)
             self.messages = [message]
     def __str__(self):
         return str(self.messages)

django/utils/functional.py

@@ -3,14 +3,22 @@ def _curried(*moreargs, **morekwargs):
         return args[0](*(args[1:]+moreargs), **dict(kwargs.items() + morekwargs.items()))
     return _curried
 
+class Promise:
+    """
+    This is just a base class for the proxy class created in
+    the closure of the lazy function. It can be used to recognize
+    promises in code.
+    """
+    pass
+
 def lazy(func, *resultclasses):
     """
     Turns any callable into a lazy evaluated callable. You need to give result
     classes or types -- at least one is needed so that the automatic forcing of
     the lazy evaluation code is triggered. Results are not memoized; the
     function is evaluated on every access.
     """
-    class __proxy__:
+    class __proxy__(Promise):
         # This inner class encapsulates the code that should be evaluated
         # lazily. On calling of one of the magic methods it will force
         # the evaluation and store the result. Afterwards, the result