eryksun added the comment:
> Interesting that “cast” accepts a byte string. If this is
> intended behaviour, it would be good to document that.
> Currently it says it takes “an object that can be
> interpreted as a pointer”.
cast makes an FFI call:
_cast = PYFUNCTYPE(py_object,
c_void_p, py_object, py_object)(_cast_addr)
def cast(obj, typ):
return _cast(obj, obj, typ)
The first arg is passed as c_void_p, i.e. a void pointer. c_void_p.from_param
accepts common objects that can be interpreted as a pointer: None (NULL),
integers, bytes, and str. It also accepts c_void_p ('P'), c_char_p ('z'),
c_wchar_p ('Z'), Array, _Pointer, _CFuncPtr, and CArgObject (byref).
If none of the latter apply, c_void_p.from_param checks for the _as_parameter_
hook. For example:
from ctypes import *
from ctypes.util import find_library
libc = CDLL(find_library('c'))
libc.atoi.argtypes = [c_void_p]
class X:
_as_parameter_ = b'123'
>>> libc.atoi(X())
123
There's also code in place to support bytearray, but it's incomplete. It uses
the z_set setfunc (defined in cfield.c), which doesn't support bytearray yet.
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<http://bugs.python.org/issue11429>
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