Hello,
OpenCascade smart pointers mechanism has to be supported in pythonOCC in
order to enable efficient access to all classes/methods in a safe way.
Roman Lygin wrote on his blog (http://opencascade.blogspot.com/) a set
of excellent articles related to Handle_*. A recent topic on OCC forum
also recently dealt with this issue when considering C# OCC wrapper
(http://www.opencascade.org/org/forum/thread_14766/).
After a few days of work, a simple solution was found to overcome the
Handle_* management issue in pythonOCC:
- each class managed by a smart pointer (ie, all classes that inhertis
from Standard_Transient) are extended with a GetHandle() method that
returns a pointer to the object. This was achived by adding the
following set of lines in the SWIG wrapper. This is an example for
gp_VectorWithNullMagnitude:
%extend gp_VectorWithNullMagnitude {
Handle_gp_VectorWithNullMagnitude GetHandle() {
return *(Handle_gp_VectorWithNullMagnitude*) &$self;
}
};
- each Handle_* class is extended with a GetObject() method that returns
the 'pointed' object (indeed a pointer to this object).
%extend Handle_gp_VectorWithNullMagnitude {
gp_VectorWithNullMagnitude* GetObject() {
return (gp_VectorWithNullMagnitude*)$self->Access();
}
};
Here is now an example of the smart pointer handle in pythonOCC:
Python 2.4.4 (#71, Oct 18 2006, 08:34:43) [MSC v.1310 32 bit (Intel)] on
win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from OCC import *
>>> V = gp_VectorWithNullMagnitude()
>>> print V
<OCC.gp_VectorWithNullMagnitude; proxy of <Swig Object of type
'gp_VectorWithNullMagnitude *' at 0x5786660> >
>>> h = V.GetHandle()
>>> print h
<OCC.Handle_gp_VectorWithNullMagnitude; proxy of <Swig Object of type
'Handle_gp_VectorWithNullMagnitude *' at
0x5786674> >
>>> V2 = h.GetObject()
>>> print V2
<OCC.gp_VectorWithNullMagnitude; proxy of <Swig Object of type
'gp_VectorWithNullMagnitude *' at 0x5786660> >
>>>
OCC pointers are not smart anymore in pythonOCC but it's a first step.
Jelle and I successfully tested this new feature with a few sample
scripts. The next step is to have a complete handle of smart pointers,
that means a complete support of the -> C++ operator defined in OCC
headers. Anyway, you can download a daily release added a couple of days
ago (http://www.pythonocc.org/Releases/daily) and test that by yourself.
Best regards,
Thomas Paviot
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