[GRASS-user] Question with Python-SWIG example [SEC=UNCLASSIFIED]

[Andrew MacIntyre]

> From: Glynn Clements

> > I also found ctypesgen:
> >
> > 	http://code.google.com/p/ctypesgen/
> 
> I finally got around to looking at this, and it took less than half an
hour to
> generate working bindings. Obviously, it will need more testing, but
unless
> any insurmountable problems show up, I intend to using this in place
of
> SWIG.

Glad you found something that you're comfortable with, and that the
effort required appears to be so modest.

> Also, I've discovered that NumPy arrays have conversion methods, e.g.
> 
>     p = buf.ctypes.data_as(POINTER(raster.CELL))
> 
> One caveat: this *doesn't* appear to increment the reference count, so
if
> you do e.g.:
> 
>     buf = buf.ctypes.data_as(POINTER(raster.CELL))
> 
> the array will be gc'd resulting in buf pointing at garbage.

This sort of issue is something that catches people in Python
(especially when using ctypes) until they learn what needs to be
preserved - its sometimes easy to lose sight of whether you've got deep
copies or shallow copies of the original.

> I haven't tried using ctypesgen for C++, though.

The material on the above website makes no mention of C++...

Regards,
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.macintyre at acma.gov.au            http://www.acma.gov.au/


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