- workaround removal of nested() in py3k

2 files changed, 35 insertions, 1 deletions

diff --git a/lib/sqlalchemy/util/__init__.py b/lib/sqlalchemy/util/__init__.py
index a8b823208..15b2ac38e 100644
--- a/lib/sqlalchemy/util/__init__.py
+++ b/lib/sqlalchemy/util/__init__.py
@@ -9,7 +9,7 @@ from .compat import callable, cmp, reduce,  \
     threading, py3k, py33, py2k, jython, pypy, cpython, win32, \
     pickle, dottedgetter, parse_qsl, namedtuple, next, reraise, \
     raise_from_cause, text_type, safe_kwarg, string_types, int_types, \
-    binary_type, \
+    binary_type, nested, \
     quote_plus, with_metaclass, print_, itertools_filterfalse, u, ue, b,\
     unquote_plus, unquote, b64decode, b64encode, byte_buffer, itertools_filter,\
     iterbytes, StringIO, inspect_getargspec, zip_longest
diff --git a/lib/sqlalchemy/util/compat.py b/lib/sqlalchemy/util/compat.py
index 7f2238a13..972fda667 100644
--- a/lib/sqlalchemy/util/compat.py
+++ b/lib/sqlalchemy/util/compat.py
@@ -226,3 +226,37 @@ def with_metaclass(meta, *bases):
                 return type.__new__(cls, name, (), d)
             return meta(name, bases, d)
     return metaclass('temporary_class', None, {})
+
+
+from contextlib import contextmanager
+
+try:
+    from contextlib import nested
+except ImportError:
+    # removed in py3k, credit to mitsuhiko for
+    # workaround
+
+    @contextmanager
+    def nested(*managers):
+        exits = []
+        vars = []
+        exc = (None, None, None)
+        try:
+            for mgr in managers:
+                exit = mgr.__exit__
+                enter = mgr.__enter__
+                vars.append(enter())
+                exits.append(exit)
+            yield vars
+        except:
+            exc = sys.exc_info()
+        finally:
+            while exits:
+                exit = exits.pop()
+                try:
+                    if exit(*exc):
+                        exc = (None, None, None)
+                except:
+                    exc = sys.exc_info()
+            if exc != (None, None, None):
+                reraise(exc[0], exc[1], exc[2])