Sorry for this incomplete message - it was intended as a note to self (at another email address) about a more complete response and I didn't catch that it would be sent to the list.
Andrew.
-------------------------> "These thoughts are mine alone!" <---------
Andrew MacIntyre Operations Branch
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-----Original Message-----
From: Andrew MacIntyre [mailto:andymac@bullseye.apana.org.au]
Sent: Monday, 3 May 2010 11:05 PM
To: Andrew MacIntyre
Subject: Re: FW: [GRASS-user] Question with Python-SWIG example
[SEC=UNCLASSIFIED]Andrew MacIntyre wrote:
>
> -------------------------> "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.macintyre@acma.gov.au http://www.acma.gov.au/
>
>
>> -----Original Message-----
>> From: Glynn Clements [mailto:glynn@gclements.plus.com]
>> Sent: Saturday, 24 April 2010 2:34 AM
>> To: Andrew MacIntyre
>> Cc: GRASS user list
>> Subject: RE: [GRASS-user] Question with Python-SWIG example
>> [SEC=UNCLASSIFIED]
>>
>>
>> Andrew MacIntyre wrote:
>>
>>>> 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)...
>> Yes, but I know how to get rid of it; I don't know how to expand it.
>>
>>>>> 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.
>> But does that convert arrays, buffers, etc?
>>
>> FWIW, the typemaps are in swig/include/python/my_typemaps.i.
>>
>> --
>> Glynn Clements <glynn@gclements.plus.com>
>
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> 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.see pyobj_to_ptr() in typemap
- what is being expected in the CObject case?
- should this be changed to use above linked APIs to extract pointers
from SWIGged pointer objects? (can't see a typemap that converts a
returned pointer to a CObject).--
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Andrew I MacIntyre "These thoughts are mine alone..."
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