[Kimchi-devel] [PATCH][Wok] Do not use default value when declare a function

[Ramon Medeiros]

For mutable object as a default parameter in function and
method-declarations the problem is, that the evaluation and creation
takes place at exactly the same moment. The python-parser reads the
function-head and evaluates it at the same moment.

Most beginers assume that a new object is created at every call, but
that's not correct. One object (in your example a list) is created at
the moment of declaration and not on demand when you are calling the
method.

For imutable objects that's not a problem, because even if all calls
share the same object, it's imutable and therefore it's properties
remain the same.

As a convention, must be used the None object for defaults to indicate
the use of a default initialization, which now can take place in the
function-body, which naturally is evaluated at call-time.

Signed-off-by: Ramon Medeiros <ramonn at linux.vnet.ibm.com>
---
 src/wok/exception.py           | 4 +++-
 src/wok/message.py             | 4 +++-
 src/wok/model/notifications.py | 4 +++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/wok/exception.py b/src/wok/exception.py
index 52f007e..90b6410 100644
--- a/src/wok/exception.py
+++ b/src/wok/exception.py
@@ -25,7 +25,9 @@ from wok.message import WokMessage
 
 
 class WokException(Exception):
-    def __init__(self, code='', args={}):
+    def __init__(self, code='', args=None):
+        if args is None:
+            args = {}
         self.code = code
         msg = WokMessage(code, args).get_text()
         cherrypy.log.error_log.error(msg)
diff --git a/src/wok/message.py b/src/wok/message.py
index a7162c7..4c35747 100644
--- a/src/wok/message.py
+++ b/src/wok/message.py
@@ -26,7 +26,9 @@ from wok.template import get_lang, validate_language
 
 
 class WokMessage(object):
-    def __init__(self, code='', args={}, plugin=None):
+    def __init__(self, code='', args=None, plugin=None):
+        if args is None:
+            args = {}
         # make all args unicode
         for key, value in args.iteritems():
             if isinstance(value, unicode):
diff --git a/src/wok/model/notifications.py b/src/wok/model/notifications.py
index e83ac56..bdb7c78 100644
--- a/src/wok/model/notifications.py
+++ b/src/wok/model/notifications.py
@@ -27,7 +27,9 @@ from wok.utils import wok_log
 notificationsStore = {}
 
 
-def add_notification(code, args={}, plugin_name=None):
+def add_notification(code, args=None, plugin_name=None):
+    if args is None:
+        args = {}
     if not code:
         wok_log.error("Unable to add notification: invalid code '%(code)s'" %
                       {'code': str(code)})
-- 
2.5.5