Using windll with complex data types

[Robin Becker]

In article <8beb91f5.0211020556.30107507 at posting.google.com>, Ben C <benc1 at today.com.au> writes
....
I use the structob module to create structured things as for pointers
they are the address of something.

so for example a lasterror function looks like

def _lastErrorMessage(n=None):
        msg = windll.cstring('',512)
        kernel32.FormatMessageA(
                        FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                        0,
                        n is None and GetLastError() or n,
                        0,
                        msg.address(),
                        len(msg)-1,
                        0
                        )
        return repr(msg)[1:-1]

we create the buffer and pass its address to the FormatMessage function.

If you really need pointer to pointer you need to create a buffer that holds the real address

eg
class pointer(structob.struct_object):
        oracle = structob.Oracle (
                'pointer',
                'Nl',
                ('ref',)
                )

then you can do

msg = windll.cstring('',512)
p=pointer()
p.ref = msg.address

so p points to msg and p.address() is a pointer to a pointer
>
>How does one pass reference to a pointer in a function?
>
>How does one retrieve data back from that pointer?
>
>How does one retrieve data back from aggregate data types such as
>structures and arrays?
>
>Thanks in advance
>
>Ben

-- 
Robin Becker