Add decorators module and test file

deluge/decorators.py

@@ -0,0 +1,51 @@
+#
+# decorators.py
+#
+# Copyright (C) 2010 John Garland <johnnybg+deluge@gmail.com>
+#
+# Deluge is free software.
+#
+# You may redistribute it and/or modify it under the terms of the
+# GNU General Public License, as published by the Free Software
+# Foundation; either version 3 of the License, or (at your option)
+# any later version.
+#
+# deluge is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with deluge.    If not, write to:
+# 	The Free Software Foundation, Inc.,
+# 	51 Franklin Street, Fifth Floor
+# 	Boston, MA  02110-1301, USA.
+#
+#    In addition, as a special exception, the copyright holders give
+#    permission to link the code of portions of this program with the OpenSSL
+#    library.
+#    You must obey the GNU General Public License in all respects for all of
+#    the code used other than OpenSSL. If you modify file(s) with this
+#    exception, you may extend this exception to your version of the file(s),
+#    but you are not obligated to do so. If you do not wish to do so, delete
+#    this exception statement from your version. If you delete this exception
+#    statement from all source files in the program, then also delete it here.
+#
+#
+
+from functools import wraps
+
+def proxy(proxy_func):
+    """
+    Factory class which returns a decorator that passes
+    the decorated function to a proxy function
+
+    :param proxy_func: the proxy function
+    :type proxy_func: function
+    """
+    def decorator(func):
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            return proxy_func(func, *args, **kwargs)
+        return wrapper
+    return decorator

tests/test_decorators.py

@@ -0,0 +1,42 @@
+from twisted.trial import unittest
+
+from deluge.decorators import proxy
+
+class DecoratorsTestCase(unittest.TestCase):
+    def test_proxy_with_simple_functions(self):
+        def negate(func, *args, **kwargs):
+            return not func(*args, **kwargs)
+
+        @proxy(negate)
+        def something(bool):
+            return bool
+
+        @proxy(negate)
+        @proxy(negate)
+        def double_nothing(bool):
+            return bool
+
+        self.assertTrue(something(False))
+        self.assertFalse(something(True))
+        self.assertTrue(double_nothing(True))
+        self.assertFalse(double_nothing(False))
+
+    def test_proxy_with_class_method(self):
+        def negate(func, *args, **kwargs):
+            return -func(*args, **kwargs)
+
+        class Test(object):
+            def __init__(self, number):
+                self.number = number
+
+            @proxy(negate)
+            def diff(self, number):
+                return self.number - number
+
+            @proxy(negate)
+            def no_diff(self, number):
+                return self.diff(number)
+
+        t = Test(5)
+        self.assertEqual(t.diff(1), -4)
+        self.assertEqual(t.no_diff(1), 4)