Index: tests/test_translationdomain.py
===================================================================
--- tests/test_translationdomain.py	(Revision 85056)
+++ tests/test_translationdomain.py	(Arbeitskopie)
@@ -92,8 +92,36 @@
                         mapping={'that': 'THAT'})
         self.assertEqual(
             translate(msgid, target_language='en', default="default",
-                         mapping={"that": "that"}), "this THAT the other")
+                      mapping={"that": "that"}), "this THAT the other")
 
+    def testMessageIDRecursiveTranslate(self):
+        factory = MessageFactory('default')
+        translate = self._domain.translate
+        msgid_sub1 = factory(u'44-not-there', '${blue}',
+                            mapping = {'blue': 'BLUE'})
+        msgid_sub2 = factory(u'45-not-there', '${yellow}',
+                            mapping = {'yellow': 'YELLOW'})
+        mapping = {'color1': msgid_sub1,
+                   'color2': msgid_sub2}
+        msgid = factory(u'46-not-there', 'Color: ${color1}/${color2}',
+                        mapping=mapping)
+        self.assertEqual(
+            translate(msgid, target_language='en', default="default"),
+            "Color: BLUE/YELLOW")
+        # The recursive translation must not change the mappings
+        self.assertEqual(msgid.mapping, {'color1': msgid_sub1,
+                                         'color2': msgid_sub2})
+        # A circular reference should not lead to crashes
+        msgid1 = factory(u'47-not-there', 'Message 1 and $msg2',
+                         mapping = {})
+        msgid2 = factory(u'48-not-there', 'Message 2 and $msg1',
+                         mapping = {})
+        msgid1.mapping['msg2'] = msgid2
+        msgid2.mapping['msg1'] = msgid1
+        self.assertRaises(RuntimeError,
+                          translate, msgid1, None, None, 'en',"default")
+
+
     def testMessageIDTranslateForDifferentDomain(self):
         domain = TranslationDomain('other')
         path = testdir()
Index: translationdomain.py
===================================================================
--- translationdomain.py	(Revision 85056)
+++ translationdomain.py	(Arbeitskopie)
@@ -62,7 +62,7 @@
         self._fallbacks = fallbacks
 
     def translate(self, msgid, mapping=None, context=None,
-                  target_language=None, default=None):
+                  target_language=None, default=None, to_translate = None):
         """See zope.i18n.interfaces.ITranslationDomain"""
 
         # if the msgid is empty, let's save a lot of calculations and return
@@ -79,10 +79,27 @@
 
         # MessageID attributes override arguments
         if isinstance(msgid, Message):
+            if to_translate == None:
+                to_translate = []
+            to_translate.append(msgid)
             if msgid.domain != self.domain:
                 util = getUtility(ITranslationDomain, msgid.domain)
+            default = msgid.default
+            # Recursively translate mappings, if they are translatable
             mapping = msgid.mapping
-            default = msgid.default
+            if mapping is not None and (
+                Message in [type(m) for m in mapping.values()]):
+                mapping = mapping.copy()
+                for key, value in mapping.items():
+                    if isinstance(value, Message):
+                        if value in to_translate:
+                            raise RuntimeError(
+                                "Circular Reference in Mappings detected")
+                        else:
+                            to_translate.append(value)
+                        mapping[key]=self.translate(value, mapping, context,
+                                                       target_language,
+                                                       default, to_translate)
 
         if default is None:
             default = unicode(msgid)