I am trying to call a DLL with a function like this:
"""DESCRIPTION: Get a list of objects attributes matching
attribute values
ARGUMENTS:
session : [in] the current session
classId : [in] the class Id of objects owning attributes to
be returned
rec : [in] record initialized with attribute values
used as search parameters (initialized by user)
nbRecords : [out] number of returned records
recordList : [out] list of returned records
flags : [in] option flags
RETURN: IVAPI_OK if OK
NOTES: recordList must be deallocated via IVFreeRecordList.
If attListSize = 0, all the attributes will be retrieved
IMPORT int WINAPI IVQueryListByExample (IVSession session, unsigned
long classId, IVRecord rec, unsigned long* nbRecords, IVRecordList*
recordList, unsigned int flags);"""
It is the recordList variable I am having trouble with. Now, recordList
is a pointer to type IvRecordList, which is itself defined as a void*
in the header file like this:
typedef void *IVRecordList;
That makes recordList a type void**. I need to get the pointers out of
the list so I can pass them back to the API when querying the contents
of each record. I am getting nbRecords telling me that the function is
returning the number of records I expect, but I'm not sure how to
define IVRecordList when I pass it in so that I can extract the
pointers properly afterwards.
I've tried this, but the record pointers seem to have a value of None.
def IVQueryListByExample(session,classId,rec,flags):
nbRecords = ctypes.c_ulong()
recordList = ctypes.c_void_p()
status = ivapidll.IVQueryListByExample(session, classId, rec,
ctypes.byref(nbRecords), ctypes.byref(recordList), flags)
Does anyone have a good idea how I should define recordList so that I
can retrieve the record pointers?
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