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

[Glynn Clements]

Martin Landa wrote:

> >> Yes, it's seems to be a ctypes issue.
> >
> > Well, the "manual" ctypes version worked earlier, so it appears to be
> > a problem with the wrappers. The preamble's String type looks
> > unnecessarily complex; there's probably a reason, but I have doubts as
> > to whether the benefits outweight the drawbacks.
> >
> > Can you try r42331? This eliminates most of the preamble, making
> > String and ReturnString aliases for c_char_p. If there's a need for
> > something more complex, I'll deal with that if and when it happens.
> 
> Sample script:
> 
> #!/usr/bin/env python
> import os, sys
> from grass.lib import grass
> from ctypes import *
> 
> grass.G_gisinit(sys.argv[0])
> 
> mapset = grass.G_find_raster2("elevation", "")
> print mapset
> 
> Result:
> 
> Traceback (most recent call last):
>   File "/home/martin/smetiste/example7.py", line 8, in <module>
>     mapset = grass.G_find_raster2("elevation", "")
> TypeError: __init__ expected at most 1 arguments, got 3

Not only can I not reproduce this, I can't see any mechanism by which
it can occur. Have you done "make clean"? What is the value of
grass.__file__ after importing it?

Given that ctypes_preamble.py defines:

	String = c_char_p
	ReturnString = c_char_p

it shouldn't be possible for this:

	G_find_raster2.argtypes = [c_char_p, c_char_p]
	G_find_raster2.restype = c_char_p

to work but this:

	G_find_raster2.argtypes = [String, String]
	G_find_raster2.restype = ReturnString

to fail.

-- 
Glynn Clements <glynn at gclements.plus.com>