Calling a function with a custom datatype argument

Hi,

I'm new to using ctypes and while things were going really well, I've 
now hit a problem and have so far been unable to find the information I 
require.  I've looked through the ctypes tutorial and reference manual, 
as well as google.  I'm hoping someone might be able to help me out.

I'm using ctypes to interface to the C library UDUNITS2.
I wish to call the function:
 
ut_error_message_handler 
ut_set_error_message_handler(ut_error_message_handler handler)

from python where the C definition of the ut_error_message_handler 
datatype is as follows:

typedef int (*ut_error_message_handler)(const char* fmt, va_list args);


[In case it helps clarify things;  handler is the name of one of the 
following functions;

Function: int ut_write_to_stderr (const char* fmt, va_list args)
Function: int ut_ignore (const char* fmt, va_list args)   ]


How do I create the ut_error_message_handler datatype in python and thus 
pass a correctly typed argument to the function?

Thanks in advance,
Rosalyn.

-- 
------------------------------------------------------------------------
Rosalyn Hatcher
NCAS Computational Modelling Services
Dept. of Meteorology, University of Reading, 
Earley Gate, Reading. RG6 6BB
Email: [email protected]     Tel: +44 (0) 118 378 6016


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