On Thu, Jul 23, 2009 at 10:29 AM, Richard Clarke<[email protected]> wrote:
> Thank you Robert, the explanation on how and where to use cdef was
> most helpful. I think it has just clicked(with a flag waving
> 'idiot').
>
> The PyCObject concept is a nice idea, removing cdef foo_t *foo from
> outside of __init__ ? However, I see implications in memory
> deallocation. How does cython currently handle memory deallocation?
>
I'm not sure you need PyCObject for your code ...
>
> I assume the best practice would be for users to deallocate memory in
> the class __del__ method (calling the appropriate wrapped c library
> destructor).
Yes. More specifically, you should allocate stuff in __cinit__(), and
deallocate stuff in __dealloc__()...
> Otherwise does cython simply free(foo) or interprets the
> language to build a depth first deallocation method?
Cython does not manage memory allocated with malloc()... you have to
manage deallocation yourself...
> I guess it
> should do the simplest free(foo), if the developer was lazy not to
> deallocate memory, they can suffer with memory leaks. I think I might
> have answered my own question here...
>
In short, you have to modify your class, using something like this
cdef class Bar: # NOTE: "cdef" class
cdef foo_t *c_foo # NOTE: "cdef" instance (not class) member!!!
def __cinit__(self): # NOTE: using "__cinit__", not "__init__"
self.c_foo = self.c_open()
def __dealloc__(self): # NOTE: using "__dealloc__", not "__del__"
if self.c_foo != NULL:
free(self.c_foo)
cdef foo_t* c_open(self): # NOTE: using "cdef", not "def", this
method will not show-up on Python side, it is a kind of internal,
private method.
cdef foo_t *foo = NULL
foo = init()
return foo
--
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
Tel/Fax: +54-(0)342-451.1594
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