difference in behaviour between declaration in .pyd and .pyx files - cython

Question

I have a pxd file that declares some types with ctypedef, and some functions with cdef. To call one particular function, I have to duplicate the typedefs in my pyx file.
If I move the cdef of the function into the pyx file it fails to compile with "Cannot convert 'state_t *' to Python object". The error refers to this line of code
retval = c_explanation.table_of_states_is_bad(<state_t*>test_array, b)
The test_array parameter is created locally with malloc so is not a python object at all.
If remove the typedefs from the pyx file and import them and the cdef from the pxd file with a from .. import *, I get the same compile error.
The only way that I can get this simple bit of code to work is with the rather awkward duplication of typedefs in both pyx and pxd files.
Any thoughts on what is going on here and how to resolve it?
The full code is pasted below
pyx file
from libc.stdlib cimport malloc, free
cimport c_explanation
cdef extern from "explanation.h":
ctypedef int state_id;
ctypedef struct event_t:
pass
ctypedef void (*event_handler)(event_t event)
ctypedef struct state_t:
state_id id
event_handler handle
char *name
ctypedef enum bool:
pass
def table_of_states_is_bad(a, b):
cdef state_t *test_array
cdef bool retval
test_array = <state_t*>malloc(len(a) * sizeof(state_t))
if not test_array:
raise MemoryError()
try:
for i, s in enumerate(a):
test_array[i].id = s[0]
retval = c_explanation.table_of_states_is_bad(test_array, b)
return retval
finally:
free(test_array)
pxd file
cdef extern from "explanation.h":
cdef int mock_get_temp(int)
ctypedef enum bool:
pass
ctypedef struct event_t:
pass
ctypedef void (*event_handler)(event_t event);
ctypedef int state_id;
ctypedef struct state_t:
state_id id
event_handler handle
char *name
cdef bool table_of_states_is_bad(state_t table[], size_t size)
finally the h file
int mock_get_temp(int);
typedef int event_id;
/* an event */
typedef struct {
event_id id; /* numeric id */
void *data; /* points to anything */
char *name; /* points to string for debug or log */
} event_t;
typedef void (*event_handler)(event_t event);
typedef enum { false, true } bool;
typedef int state_id;
/* a state */
typedef struct {
state_id id; /* numeric id */
event_handler handle; /* points to handler */
char *name; /* points to string for debug or log */
} state_t;
bool table_of_states_is_bad(state_t table[], size_t size);

Answer 1

After some reading and experimentation I worked out what I had done wrong.
The problem is one of namespaces. When using the import * format, the local definition of table_of_states_is_bad() was replacing the imported one. Thus the function call was to the cython version of the function rather than to the c version and hence the error was correctly reported.
I solved the problem by renaming the local function to wrap_table_of_states_is_bad() hence resolving the name conflict.