- tried it out in my work project, and realized the "op" and "context…

…" namespaces

need to be there fully and in particular "context" needs to be
a proxy object, as env.py may have dependencies which live beyond the
scope of the migration script.   Will have to try to make
these proxies as straightforward as possible.
- more architecture docs

alembic/__init__.py

@@ -5,8 +5,11 @@
 package_dir = path.abspath(path.dirname(__file__))
 
 
-class _OpProxy(object):
-    _proxy = None
+from alembic import op
+
+class _ContextProxy(object):
+    """A proxy object for the current :class:`.EnvironmentContext`."""
     def __getattr__(self, key):
-        return getattr(self._proxy, key)
-op = _OpProxy()
+        return getattr(_context, key)
+context = _ContextProxy()
+

alembic/environment.py

@@ -46,11 +46,11 @@ def __enter__(self):
         be made available as ``from alembic import context``.
     
         """
-        alembic.context = self
+        alembic._context = self
         return self
 
     def __exit__(self, *arg, **kw):
-        del alembic.context
+        alembic._context = None
         alembic.op._proxy = None
 
     def is_offline_mode(self):

alembic/op.py

@@ -0,0 +1,19 @@
+from alembic.operations import Operations
+
+# create proxy functions for 
+# each method on the Operations class.
+
+# TODO: this is a quick and dirty version of this.
+# Ideally, we'd be duplicating method signatures 
+# and such, using eval(), etc.
+
+_proxy = None
+def _create_op_proxy(name):
+    def go(*arg, **kw):
+        return getattr(_proxy, name)(*arg, **kw)
+    go.__name__ = name
+    return go
+
+for methname in dir(Operations):
+    if not methname.startswith('_'):
+        locals()[methname] = _create_op_proxy(methname)