[PyKDE] sip_is_py_method

Phil Thompson phil at riverbankcomputing.co.uk
Sun Aug 15 19:49:13 BST 2004

On Monday 09 August 2004 3:18 am, Patrick wrote:
> sorry, I'd copy the original message, but I haven't been getting much mail
> lately for some reason.
> Anyway, Phil, in response to you suggesting I 'compile with tracing
> enabled', I've done it  with PyQt, but my problem lies with my
> sip-generated module wrapping my C++ library, and there isn't an option for
> compiling with tracing. What sort of 'tracing' would that be, anyway?

Tracing is a function of SIP, not PyQt. See the SIP documentation to see how 
to build your module with it supported and how to enable it at runtime.

I implemented it because it can be very difficult to work out the execution 
path of a C++ program with lots of virtuals by just looking at the source 


> Here is the original message:
> On Sunday 01 August 2004 9:56 pm, Patrick wrote:
> > I've run into a problem with virtual functions and sip-4. The problem
> > does not exist in sip-3.
> >
> > I have a superclass with a (non-pure) virtual function, and a couple of
> > subclasses that re-implement it. I create an object or two of the
> > subclasses and register them with my C++ library through an exposed
> > python method. My C++ code then calls the virtual functions, which are
> > *not* reimplemented in python.
> > The problem is that when sip_api_is_py_method is called, that thread
> > stops when it tries to acquire the GIL. I have checked that don't have
> > ANY calls from C++ into python via virtual methods (which is where
> > another thread could have acquired the lock and not returned),
> >
> > Where else should I look, and would this be some sort of a bug or another
> > caveat for using C++ bindings?
> I'd rebuild with tracing enabled to make absolutely sure what's actually
> being called and when.
> If sip_api_is_py_method() is blocking then it must be in the call to
> PyGILState_Ensure(). The latter is a small function so it should be easy to
> add debug statements to it and see exactly what's going on.
> Phil
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