Add an alternative __next__() API to pass arbitrary exceptions in. I

like this better.

pep-0340.txt

@@ -282,6 +282,57 @@ Specification: Generator Exception Handling
     cases work differently; in Python, you cannot save the block for
     later use, and you cannot test whether there is a block or not.
 
+Specification: Alternative __next__() and Generator Exception Handling
+
+    The above specification doesn't let the generator handle general
+    exceptions.  If we want that, we could modify the __next__() API
+    to take either a value or an exception argument.  When it is an
+    Exception instance, it is raised at the point of the resuming
+    yield; otherwise it is returned from the yield-expression (or
+    ignored by a yield-statement).  Wrapping a regular value in a
+    ContinueIteration is then no longer necessary.  The translation of
+    a block-statement would become:
+
+        itr = EXPR1
+        arg = val = None
+        ret = False
+        while True:
+            try:
+                VAR1 = next(itr, arg)
+            except StopIteration:
+                if ret:
+                    return val
+                break
+            try:
+                arg = val = None
+                ret = False
+                BLOCK1
+            except Exception, arg:
+                pass
+
+    The translation of "continue EXPR2" would become:
+
+        arg = EXPR2
+        continue
+
+    The translation of "break" inside a block-statement would become:
+
+        arg = StopIteration()
+        continue
+
+    The translation of "return EXPR3" inside a block-statement would
+    become:
+
+        val = EXPR3
+        arg = StopIteration()
+        ret = True
+        continue
+
+    The translation of a for-loop would be the same as indicated
+    earlier (inside a for-loop only the translation of "continue
+    EXPR2" is changed; break and return translate to themselves in
+    that case).
+
 Alternatives Considered
 
     TBD.