[PyQt] 'pyqt@riverbankcomputing.com'

[Dr Andrew Perella]

Ok - I got the bottom of this.
 
1) I had a c++ class with no virtual destructor defined.
2) I wrapped it in sip.
3) Constructed an instance in python
4) Transferred ownership to C++
5) allowed c++ to delete it
 
The sip wrapper still continued to live in the cpp to wrapper hash map.
This would cause nasty crashes.
 
I wonder if there is anything that can be done to fix this or at least
detect it? Adding a virtual destructor and exposing that in the sip
definition fixed it of course.
 
Regards,
Andrew
 

  _____  

From: pyqt-bounces at riverbankcomputing.com
[mailto:pyqt-bounces at riverbankcomputing.com] On Behalf Of Dr Andrew Perella
Sent: 08 November 2007 23:09
To: pyqt at riverbankcomputing.com
Subject: [PyQt] 'pyqt at riverbankcomputing.com'


I get exactly the same objmap.c crash as you in an application I have
written using SIP (but not PyQT).
The crash is timing related - depending on when the garbage collector is
called, the sip hashmap still has a reference sometimes to a freed python
wrapper.
I will investigate further.
 
Cheers,
Andrew
 
P.S. I made the same "fix" you did to objmap.c:
 
while (w != NULL)

{

/* We are removing it from the map here. */

sipSetNotInMap(w);

sip_api_common_dtor(w);

 w = w->next;

 

//extra code "fix" here

if (w==0xdbdbdbdb)

{

printf("WARNING: SIP would normally crash - would try to access freed
memory\n");

w=NULL;

}

}

 

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