[Zope-dev] Re: Zope2 porting..module Zope2

[Tres Seaver]

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ranjith kannikara wrote:
> During the porting of Zope2 to python2.5 We are now porting the
> module Zope2 which was having 4
> failures and 1 error. All of these were due to the change in the
> hierarchy of exception classes. The failures were arised due to the
> failure of the function 'SetStatus' in   / **
> /lib/python/ZPublisher/HTTPResponse.py to set the status. In the above
> function there is one checking
>  if( isinstance(status, types.ClassType) and issubclass(status, Exception)):
>                    status = status.__name__    #status is being set here..
> 
> in which status is actually the zException class and it is new style
> class in python2.5 , therefore this condition always fails and the
> status is set to arbitrary value 500.
> We tried removing this first condition ( ie using
> if(issubclass(status, types.ClassType ) ) and it didn't show any new
> failures or errors in either python2.4 or 2.5 . And the 4 failures
> also got vanished. We tried to make out the significance of that first
> checking but couldn't.
> 
> What is the significance of this checking ?  ( so that the code can be
> edited to adopt the
> checking in someother way for python2.5 )
> Or Can it be just avoided?

Just to clarify, are you proposing the following patch?

- --- lib/python/ZPublisher/HTTPResponse.py	(revision 87245)
+++ lib/python/ZPublisher/HTTPResponse.py	(working copy)
@@ -217,8 +217,7 @@
             # It has already been determined.
             return

- -        if (isinstance(status, types.ClassType)
- -         and issubclass(status, Exception)):
+        if issubclass(status, Exception):
             status = status.__name__

         if isinstance(status, str):
@@ -722,8 +721,9 @@
         else:
             t, v, tb = sys.exc_info()

- -        if t == 'Unauthorized' or t == Unauthorized or (
- -            isinstance(t, types.ClassType) and issubclass(t,
Unauthorized)):
+        if (t == 'Unauthorized' or
+            t == Unauthorized or
+            issubclass(t, Unauthorized)):
             t = 'Unauthorized'
             self._unauthorized()

If so, -1:  that pattern landed initially in a commit in early 2001, and
is due to the fact that the 'issubclass' test blows up when used on a
non-class type.  An alternative patch allows for both new and old-style
classes::

- --- lib/python/ZPublisher/HTTPResponse.py	(revision 87245)
+++ lib/python/ZPublisher/HTTPResponse.py	(working copy)
@@ -217,7 +217,7 @@
             # It has already been determined.
             return

- -        if (isinstance(status, types.ClassType)
+        if (isinstance(status, (type, types.ClassType))
          and issubclass(status, Exception)):
             status = status.__name__

@@ -723,7 +723,8 @@
             t, v, tb = sys.exc_info()

         if t == 'Unauthorized' or t == Unauthorized or (
- -            isinstance(t, types.ClassType) and issubclass(t,
Unauthorized)):
+            isinstance(t, (type, types.ClassType)) and
+            issubclass(t, Unauthorized)):
             t = 'Unauthorized'
             self._unauthorized()





Tres.
- --
===================================================================
Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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