[PyKDE] Found cure for bizarre backtrace - ???

[Phil Thompson]

Bill Soudan wrote:

> On Tue, 2 Jul 2002, Bill Soudan wrote:
> 
> 
>>I'm going to do some more debugging today.  If I can't find anything else 
>>out about the exception, I'll prune the code down and post it.
>>
> 
> Alright, I've narrowed the culprit down to my subclassed QListViewItem.
> I add a single MonitorItem to the listview, send rapid-fire XMLRPC 
> messages to the GUI, and when I click on the item, the exception occurs.
> 
> class MonitorItem(QListViewItem):
>   def __init__(self, host, port, parent = None, name = None):
>     QListViewItem.__init__(self, parent, name)
> 
>   def text(self, column):
>     return 'test'
> 
> I've found two different ways to get rid of the dump:
> 
> 1) don't override the text method.  Not really practical.
> 
> 2) modify the text method to return QString('text') instead of just 'text'.
> 
> I always thought PyQt is supposed to convert between Python strings and
> QStrings automatically.  I reviewed the docs though and they don't
> specifically say whether returning Python strings from C++ methods is
> acceptable, nor does QListViewItem have any caveats listed.  So is #2 the
> proper fix?


No, you shouldn't need to do it - it should be done for you. The 
generated code that does it is sipForceConvertTo_QString() and 
sipConvertTo_QString(). Your #2 means a different code path is taken in 
the latter function.

I think the exception is a false one. Try the following fix to 
sipTransferSelf() in siplib.c (the comment just above this code gives 
some explaination).

             if ((sipThis = sipMapSelfToThis(sipSelf)) != NULL)
             {
                     if (toCpp)
                     {
                             sipResetPyOwned(sipThis);

                             if (!sipIsExtraRef(sipThis))
                             {
                                     sipSetIsExtraRef(sipThis);
                                     Py_INCREF(sipSelf);
                             }
                     }
                     else
                     {
                             sipSetPyOwned(sipThis);

                             if (sipIsExtraRef(sipThis))
                             {
                                     sipResetIsExtraRef(sipThis);
                                     Py_DECREF(sipSelf);
                             }
                     }
             }
 >>> Add the following two lines <<<
             else
                     PyErr_Clear();

Phil