Several non-functional improvements to the code base.

Reduce the explicit use of the config.db global by introducing two new
helpers:
 - A new transaction() context manager which will commit the transaction on
   successful exit, otherwise it will abort the transaction
 - A new dbconnection decorator which calls the decorated method with the
   Storm store object as the first argument (after self).  This can be used
   instead of config.db.store.

By reducing the explicit use of this global, we have a better chance of
refactoring it away in the future.  Still TODO: runner.py and lmtp.py.

Be explicit about the `store` attribute on the IDatabase interface.

More consistent use of __future__ imports.

Remove an obsolete command line script.

1 files changed, 39 insertions, 13 deletions

diff --git a/src/mailman/database/transaction.py b/src/mailman/database/transaction.py
index 7a6ba00af..295f3d567 100644
--- a/src/mailman/database/transaction.py
+++ b/src/mailman/database/transaction.py
@@ -21,15 +21,32 @@ from __future__ import absolute_import, print_function, unicode_literals
 
 __metaclass__ = type
 __all__ = [
+    'dbconnection',
+    'transaction',
     'transactional',
     ]
 
 
+from contextlib import contextmanager
+
 from mailman.config import config
 
 
 
-class transactional:
+@contextmanager
+def transaction():
+    """Context manager for ensuring the transaction is complete."""
+    try:
+        yield
+    except:
+        config.db.abort()
+        raise
+    else:
+        config.db.commit()
+
+
+
+def transactional(function):
     """Decorator for transactional support.
 
     When the function this decorator wraps exits cleanly, the current
@@ -38,16 +55,25 @@ class transactional:
 
     Either way, the current transaction is completed.
     """
-    def __init__(self, function):
-        self._function = function
+    def wrapper(*args, **kws):
+        try:
+            rtn = function(*args, **kws)
+            config.db.commit()
+            return rtn
+        except:
+            config.db.abort()
+            raise
+    return wrapper
 
-    def __get__(self, obj, type=None):
-        def wrapper(*args, **kws):
-            try:
-                rtn = self._function(obj, *args, **kws)
-                config.db.commit()
-                return rtn
-            except:
-                config.db.abort()
-                raise
-        return wrapper
+
+
+def dbconnection(function):
+    """Decorator for getting at the database connection.
+
+    Use this to avoid having to access the global `config.db.store`
+    attribute.  This calls the function with `store` as the first argument.
+    """
+    def wrapper(*args, **kws):
+        # args[0] is self.
+        return function(args[0], config.db.store, *args[1:], **kws)
+    return wrapper