Removed some dead code and simplified some other ocde

 ctypes prototypes.

"""

from ctypes import c_void_p, string_at

from django.contrib.gis.gdal.error import check_err, OGRException, SRSException

from django.contrib.gis.gdal.libgdal import lgdal

from django.utils import six

# Helper routines for retrieving pointers and/or values from

# arguments passed in by reference.

def arg_byref(args, offset=-1):

    "Returns the pointer argument passed in by-reference."

    return args[offset]._obj

def check_bool(result, func, cargs):

    "Returns the boolean evaluation of the value."

    if bool(result):

        return True

    else:

        return False

### String checking Routines ###

def check_const_string(result, func, cargs, offset=None):

    """

    Check the error code returned (c_int).

    """

    check_err(result)

    return

def check_pointer(result, func, cargs):

    "Makes sure the result pointer is valid."

from ctypes import c_char_p, c_double, c_int, c_void_p, POINTER

from django.contrib.gis.gdal.envelope import OGREnvelope

from django.contrib.gis.gdal.libgdal import lgdal

from django.contrib.gis.gdal.prototypes.errcheck import check_bool, check_envelope

from django.contrib.gis.gdal.prototypes.errcheck import check_envelope

from django.contrib.gis.gdal.prototypes.generation import (const_string_output,

    double_output, geom_output, int_output, srs_output, string_output, void_output)

def topology_func(f):

    f.argtypes = [c_void_p, c_void_p]

    f.restype = c_int

    f.errchck = check_bool

    f.errchck = bool

    return f

### OGR_G ctypes function prototypes ###

    from ..error import GEOSIndexError

def getItem(o,i):

    return o[i]

def delItem(o,i):

    del o[i]

def setItem(o,i,v):

    o[i] = v

if HAS_GEOS:

    def api_get_distance(x):

        return x.distance(Point(-200,-200))