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

[Andrew MacIntyre]

[Oops - original inadvertently sent only to Glynn, again :-(]

> From: Glynn Clements
> 
> Andrew MacIntyre wrote:
> 
> > After some googling, it seems that the pointer address should be 
> > obtainable by using int() on the pointer object returned by the SWIG 
> > wrapper (i.e. int(p) in the above example), with the resulting value 
> > usable in ctypes' from_address() method.  I might be wrong, but I 
> > think that e.g. ctypes.c_void_p(int(p)) might also work to create a 
> > ctypes void pointer instance.
> 
> That doesn't seem to work either:
> 
> 	> import grass.lib.grass as gis
> 	> import grass.lib.raster as rast
> 	> import ctypes
> 	> gis.G_gisinit("")
> 	> p = rast.Rast_allocate_c_buf()
> 	> a = ctypes.cast(int(p), ctypes.POINTER(ctypes.c_int))
> 	> infd = rast.Rast_open_old("elevation.dem", "")
> 	> rast.Rast_get_c_row(infd, a, 10)

I think the above line should read:

 	rast. Rast_get_c_row(infd, p, 10)

> 	> a[0]

Then this might work.

-------------------------> "These thoughts are mine alone!" <---------
Andrew MacIntyre           Operations Branch
tel:   +61 2 6219 5356     Communications Infrastructure Division
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email: andrew.macintyre at acma.gov.au            http://www.acma.gov.au/

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