inhahe wrote:
> I need to make a list of instances of a Structure, then I need to make an
> instance of another Structure, one of the fields of which needs to be an
> arbitrary-length array of pointers to the instances in the list. How do I
> do that?
>
> Just in case it helps, I'll include what I tried that didn't work:
> ------
> class NoteEvent(ctypes.Structure):
> _fields_ = [('type', ctypes.c_int),
> ('byteSize', ctypes.c_int),
> ('deltaFrames', ctypes.c_int),
> ('flags', ctypes.c_int),
> ('noteLength', ctypes.c_int),
> ('noteOffset', ctypes.c_int),
> ('commandCode', ctypes.c_char),
> ('noteNumber', ctypes.c_char),
> ('velocity', ctypes.c_char)]
>
> def mkVstEvents(events):
> class Events(ctypes.Structure):
> _fields_ = [('numEvents', ctypes.c_int),
> ('reserved', ctypes.c_int),
> ('eventspointerarray', ctypes.c_void_p * len(events))]
> return Events(len(events), 0, tuple([ctypes.pointer(event) for event in
> events]))
...
> RuntimeError: (c_void_p_Array_1) <type 'exceptions.TypeError'>:
> incompatible types, LP_NoteEvent instance instead of c_void_p instance
Two things that you can try:
> ('eventspointerarray', ctypes.c_void_p * len(events))]
Either change c_void_p to POINTER(NoteEvent) like
https://stackoverflow.com/questions/7015487/ctypes-variable-length-structures
or cast the NoteEvent pointer to void *:
> return Events(len(events), 0, tuple([ctypes.pointer(event) for event in
> events]))
... cast(pointer(event), c_void_p) ...
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