[PyQt] casting issues
Diez B. Roggisch
deets at web.de
Thu Sep 17 00:28:52 BST 2009
Hi,
when wrapping a C++-library with SIP ( 4.9-snapshot-20090821) I run into
a couple of issues.
First of all, the library I wrap has a hierarchy of classes (all
descending from ISceneNode) which I wrapped.
Now through an instance of a so-called ISceneManager, I can access
instances of the current scene-graph which are ISceneNode-instances.
Consequently, the signature for one of the accessory-methods looks like
this:
ISceneNode *getSceneNodeFromID(int)
So far, so good.
Now problem number one comes up: I *know* a certain node is of type e.g.
IMeshSceneNode. But when I access it via the above method, all I get is
an ISceneNode. My C++-foo is rusty, and I know that RTTI isn't always
available - I just wonder: is there a way for SIP to figure out the
actual type of the instance returned, and wrap it accordingly? If yes,
what do I need to do to enable that feature?
However, the library in question offers a getType()-call on ISceneNodes,
and this I can use to write casting-code myself.
So I tried sip.cast, and that's my second issue for today: this
dramatically segfaults for me.
What works though is sip.unwrapinstance and sip.wrapinstance called in
succession. The subsequent tinkering with the nodes shows that it
actually works.
So the question is - why does sip.cast bomb? I use it like this:
sip.cast(terrain, scene.IMeshSceneNode)
Regards,
Diez
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