#7 assigning array to POINTER structure member fails badly

[John Kabir Luebs]

I have a structure that looks like the following:

class S(Structure):
_fields_ = [("a", POINTER(c_int))]

s = S()
ia = (c_int * 10)()
s.a = ia
print s.a.contents

The s.a.contents causes the following:
SystemError: ../Objects/listobject.c:105: bad argument
to internal
function

Using the sequence getitem as in: s.a[0] works. However
if you try to assign to it like s.a[0] = 1, the same
exception is thrown.

Clearly it would be nice to allow pointer members to
point to arrays of objects of the respective type. I
understand that this may not be a supported feature of
the Pointer type when it is a struct field. It appears
like this may be supported because the the getitem
access of s.a will reflect the contents of ia.

Regardless, ctypes should probably not allow a type
error like this to reach so far into the Python runtime.

So the actual nature of this bug is unknown. It is
unclear whether assigning an array to a pointer like
this is an allowed feature (it half works at least). It
may be that the pointer access is meant to be read
only. If so, then the error handling should probably be
polished.

[Thomas Heller]

Logged In: YES
user_id=11105

This is a bug deep inside ctypes. I will investigate it,
but it may take some time.

As a workaround, you should initialize the array *before*
storing it in the structure. If that's possible.

[Thomas Heller]

Logged In: YES
user_id=11105

As I said, deep changes had to be made to make this work.
But now it is fixed, in ctypes 0.9.5.

Thanks.