-

cool-RR · cool-RR · commit b1855393e52d · 2012-06-23T00:50:10.000+03:00
diff --git a/python_toolbox/context_managers/__init__.py b/python_toolbox/context_managers/__init__.py
@@ -133,3 +133,4 @@ def do_stuff():
 from .blank_context_manager import BlankContextManager
 from .reentrant_context_manager import ReentrantContextManager
 from .delegating_context_manager import DelegatingContextManager
+from .functions import nested
diff --git a/python_toolbox/context_managers/functions.py b/python_toolbox/context_managers/functions.py
@@ -0,0 +1,41 @@
+# Copyright 2009-2012 Ram Rachum.
+# This program is distributed under the MIT license.
+
+'''
+This module defines various functions.
+
+See their documentation for more information.
+'''
+
+from .context_manager_type import ContextManagerType
+
+
+@ContextManagerType
+def nested(*managers):
+    # Code from `contextlib`
+    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):
+            # Don't rely on sys.exc_info() still containing
+            # the right information. Another exception may
+            # have been raised and caught by an exit method
+            raise exc[0], exc[1], exc[2]
+    
diff --git a/test_python_toolbox/test_context_managers/test_nested.py b/test_python_toolbox/test_context_managers/test_nested.py
@@ -0,0 +1,33 @@
+# Copyright 2009-2012 Ram Rachum.
+# This program is distributed under the MIT license.
+
+'''Test the `python_toolbox.context_managers.nested` function.'''
+
+from __future__ import with_statement 
+
+from python_toolbox import cute_testing
+
+from python_toolbox.context_managers import ReentrantContextManager, nested
+
+
+
+def test_nested():
+    '''Test the basic workings of `nested`.'''
+    
+    a = ReentrantContextManager()
+    b = ReentrantContextManager()
+    c = ReentrantContextManager()
+    
+    with nested(a):
+        assert (a.depth, b.depth, c.depth) == (1, 0, 0)
+        with nested(a, b):
+            assert (a.depth, b.depth, c.depth) == (2, 1, 0)
+            with nested(a, b, c):
+                assert (a.depth, b.depth, c.depth) == (3, 2, 1)
+                
+        with nested(c):
+            assert (a.depth, b.depth, c.depth) == (1, 0, 1)
+            
+    assert (a.depth, b.depth, c.depth) == (0, 0, 0)
+            
+            
