unicode: Implemented string interpolation for lazy objects.

git-svn-id: http://code.djangoproject.com/svn/django/branches/unicode@5420 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/utils/functional.py

@@ -32,9 +32,11 @@ def lazy(func, *resultclasses):
                 self.__dispatch[resultclass] = {}
                 for (k, v) in resultclass.__dict__.items():
                     setattr(self, k, self.__promise__(resultclass, k, v))
-            if unicode in resultclasses:
+            self._delegate_str = str in resultclasses
+            self._delegate_unicode = unicode in resultclasses
+            assert not (self._delegate_str and self._delegate_unicode), "Cannot call lazy() with both str and unicode return types."
+            if self._delegate_unicode:
                 self.__unicode__ = self.__unicode_cast
-            self._delegate_str  = str in resultclasses
 
         def __promise__(self, klass, funcname, func):
             # Builds a wrapper around some magic method and registers that magic
@@ -62,6 +64,14 @@ def lazy(func, *resultclasses):
             else:
                 return Promise.__str__(self)
 
+        def __mod__(self, rhs):
+            if self._delegate_str:
+                return str(self) % rhs
+            elif self._delegate_unicode:
+                return unicode(self) % rhs
+            else:
+                raise AssertionError('__mod__ not supported for non-string types')
+
     def __wrapper__(*args, **kw):
         # Creates the proxy object, instead of the actual value.
         return __proxy__(args, kw)

django/utils/translation/__init__.py

@@ -70,7 +70,7 @@ ngettext_lazy = lazy(ngettext, str)
 gettext_lazy = lazy(gettext, str)
 ungettext_lazy = lazy(ungettext, unicode)
 ugettext_lazy = lazy(ugettext, unicode)
-string_concat = lazy(string_concat, str, unicode)
+string_concat = lazy(string_concat, unicode)
 
 def activate(language):
     return real_activate(language)

tests/regressiontests/i18n/tests.py

@@ -0,0 +1,17 @@
+# coding: utf-8
+
+ur"""
+>>> from django.utils.translation import ugettext_lazy, activate, deactivate
+>>> s = ugettext_lazy('Add %(name)s')
+>>> d = {'name': 'Ringo'}
+>>> s % d
+u'Add Ringo'
+>>> activate('de')
+>>> s % d
+u'Ringo hinzuf\xfcgen'
+>>> activate('pl')
+>>> s % d
+u'Dodaj Ringo'
+>>> deactivate()
+
+"""