ctypes: pointer to method

Nobody nobody at nowhere.com
Thu Aug 5 21:32:25 CEST 2010


On Thu, 05 Aug 2010 10:50:21 -0700, Martin Landa wrote:

> is it possible to pass pointer to a method using ctypes.

I don't know about methods, but it works for functions.

> Sample code:
> 
>     ...
>     G_set_error_routine(byref(self._print_error))

This won't work; you have to be more explicit, e.g.:

	errtype = CFUNCTYPE(c_int, POINTER(c_char), POINTER(c_int))
	errfunc = errtype(print_error)
	G_set_error_routine(errfunc)

NOTE: be sure to keep a reference to the wrapper, as ctypes doesn't hold
references itself. IOW, you can't replace the above with:

	errtype = CFUNCTYPE(c_int, POINTER(c_char), POINTER(c_int))
	G_set_error_routine(errtype(print_error))

If you do this, the wrapper is eligible for garbage collection as soon as
G_set_error_routine() returns, and will probably have vanished by the time
that G_fatal_error() gets called.

For more information see:

	http://docs.python.org/library/ctypes.html#callback-functions




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