Introduce IUnboundStreamIterator to support publishing iterators of unknown length

src/ZPublisher/Iterators.py

 from zope.interface import Interface
 from zope.interface import implements
 
-class IStreamIterator(Interface):
+class IUnboundStreamIterator(Interface):
+    """
+    An iterator with unknown length that can be published.
     """
-    An iterator that can be published.
-
-    IStreamIterators must not read from the object database.
-    After the application finishes interpreting a request and 
-    returns an iterator to be processed asynchronously, it closes 
-    the ZODB connection. If the iterator then tries to load some 
-    ZODB object, ZODB would do one of two things.  If the connection 
-    is still closed, ZODB would raise an error. If the connection 
-    happens to be re-opened by another thread, ZODB might allow it, 
-    but it has a chance of going insane if it happens to be loading 
-    or storing something in the other thread at the same time.                      """
 
     def next():
         """
@@ -21,6 +12,21 @@ class IStreamIterator(Interface):
         StopIeration if we've reached the end of the bytestream.
         """
 
+
+class IStreamIterator(Interface):
+    """
+    An iterator with known length that can be published.
+
+    IStreamIterators must not read from the object database.
+    After the application finishes interpreting a request and
+    returns an iterator to be processed asynchronously, it closes
+    the ZODB connection. If the iterator then tries to load some
+    ZODB object, ZODB would do one of two things.  If the connection
+    is still closed, ZODB would raise an error. If the connection
+    happens to be re-opened by another thread, ZODB might allow it,
+    but it has a chance of going insane if it happens to be loading
+    or storing something in the other thread at the same time.                      """
+
     def __len__():
         """
         Return an integer representing the length of the object

src/ZPublisher/WSGIPublisher.py

@@ -32,7 +32,7 @@ from ZPublisher.Publish import dont_publish_class
 from ZPublisher.Publish import get_module_info
 from ZPublisher.Publish import missing_name
 from ZPublisher.pubevents import PubStart, PubBeforeCommit, PubAfterTraversal
-from ZPublisher.Iterators import IStreamIterator
+from ZPublisher.Iterators import IUnboundStreamIterator, IStreamIterator
 
 _NOW = None     # overwrite for testing
 def _now():
@@ -137,10 +137,13 @@ class WSGIResponse(HTTPResponse):
             body.seek(0)
             self.setHeader('Content-Length', '%d' % length)
             self.body = body
-        elif IStreamIterator.providedBy(body):
+        elif IUnboundStreamIterator.providedBy(body):
             self.body = body
             self._streaming = 1
             HTTPResponse.setBody(self, '', title, is_error)
+        elif IStreamIterator.providedBy(body):
+            self.body = body
+            HTTPResponse.setBody(self, '', title, is_error)
         else:
             HTTPResponse.setBody(self, body, title, is_error)
 

src/ZPublisher/tests/test_WSGIPublisher.py

@@ -136,6 +136,28 @@ class WSGIResponseTests(unittest.TestCase):
                                 time.gmtime(time.mktime(WHEN)))
         self.assertTrue(('Date', whenstr) in headers)
 
+    def test_setBody_IUnboundStreamIterator(self):
+        from ZPublisher.Iterators import IUnboundStreamIterator
+        from zope.interface import implements
+
+        class test_streamiterator:
+            implements(IUnboundStreamIterator)
+            data = "hello"
+            done = 0
+
+            def next(self):
+                if not self.done:
+                    self.done = 1
+                    return self.data
+                raise StopIteration
+
+        response = self._makeOne()
+        response.setStatus(200)
+        body = test_streamiterator()
+        response.setBody(body)
+        response.finalize()
+        self.assertTrue(body is response.body)
+
     def test_setBody_IStreamIterator(self):
         from ZPublisher.Iterators import IStreamIterator
         from zope.interface import implements
@@ -151,6 +173,9 @@ class WSGIResponseTests(unittest.TestCase):
                     return self.data
                 raise StopIteration
 
+            def __len__(self):
+                return len(self.data)
+
         response = self._makeOne()
         response.setStatus(200)
         body = test_streamiterator()