Address most of Phillip Eby's comments.

pep-0343.txt

@@ -282,6 +282,8 @@ Specification: Generator Enhancements
                 raise TypeError("generator ignored GeneratorExit")
             # Other exceptions are not caught
 
+    (XXX is TypeError an acceptable exception here?)
+
   New generator method: __del__()
 
     g.__del__() is an alias for g.close().  This will be called when
@@ -350,8 +352,10 @@ Generator Decorator
         @with_template
         def opening(filename):
            f = open(filename) # IOError here is untouched by Wrapper
-           yield f
-           f.close() # Ditto for errors here (however unlikely)
+           try:
+               yield f
+           finally:
+               f.close() # Ditto for errors here (however unlikely)
 
     A robust implementation of this decorator should be made part of
     the standard library, but not necessarily as a built-in function.
@@ -427,20 +431,17 @@ Examples
                 print line.rstrip()
 
     3. A template for committing or rolling back a database
-       transaction; this is written as a class rather than as a
-       decorator since it requires access to the exception
-       information:
+       transaction:
 
-        class transactional:
-            def __init__(self, db):
-                self.db = db
-            def __enter__(self):
-                self.db.begin()
-            def __exit__(self, type, value, tb):
-                if type is not None:
-                    self.db.rollback()
-                else:
-                    self.db.commit()
+        @with_template
+        def transactional(db):
+            db.begin()
+            try:
+                yield None
+            except:
+                db.rollback()
+            else:
+                db.commit()
 
     4. Example 1 rewritten without a generator: