> From: Glynn Clements > Andrew MacIntyre wrote: > > > > That was what I tried first, but it results in Rast_get_c_row() > > > segfaulting. > > > > Then it seems to me that there's some problem with the SWIG wrapper for > > Rast_get_c_row(), if it won't accept a valid SWIG pointer object > > returned from another wrapped function. > > That's what I suspect, namely that the typemap for pointers is getting > in the way. > > Removing the typemap would mean that you couldn't pass a Python > string, array, buffer, sequence, etc directly to a GRASS function, but > would have to explicitly allocate and populate a block of memory.
I don't think you need to get rid of the typemap - I suspect you might have to expand it to distinguish between the different types of pointers though (see below)... > > > There is a typemap for pointers, which converts a CObject, string, > > > buffer or sequence. I have no idea how to test for or convert a > > > SWIG-wrapped pointer. > > > > In the SWIG wrapper? I see a note about SWIG_ConvertPtr() in > > http://www.swig.org/Doc1.3/Python.html#Python_nn64 ? > > That might help, although I still don't know how to test whether a > given "PyObject *" is a SWIG-wrapped pointer. I get the impression from the above linked documentation that, for example, there should be an explicit typemap reference for CELL pointers (as returned by Rast_allocate_c_buf()) and that the typemap for CELL pointers as an input argument should use SWIG_ConvertPtr(), which will set an exception if the inbound object is not a suitable input (if the exception flag is used; returning NULL will then propagate the exception). As far as SWIGged pointers go, this seems to be the closest you can get to Python's *Check* APIs. Cheers, Andrew. -------------------------> "These thoughts are mine alone!" <--------- Andrew MacIntyre Operations Branch tel: +61 2 6219 5356 Communications Infrastructure Division fax: +61 2 6253 3277 Australian Communications & Media Authority email: andrew.macint...@acma.gov.au http://www.acma.gov.au/ If you have received this email in error, please notify the sender immediately and erase all copies of the email and any attachments to it. The information contained in this email and any attachments may be private, confidential and legally privileged or the subject of copyright. If you are not the addressee it may be illegal to review, disclose, use, forward, or distribute this email and/or its contents. Unless otherwise specified, the information in the email and any attachments is intended as a guide only and should not be relied upon as legal or technical advice or regarded as a substitute for legal or technical advice in individual cases. Opinions contained in this email or any of its attachments do not necessarily reflect the opinions of ACMA. _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
