On Thursday, April 19, 2012 12:25:29 PM UTC-7, csd wrote:

>  Hi all,

> I am trying to wrap some C++ code in Cython and am having trouble with
> references. Here is a code snippet:

> cdef extern from "mapped_matrix_ext.h":

> cdef cppclass mapped_matrix_ext[T]:

> mapped_matrix_ext(int, int, int)

> mapped_matrix_ext[T]& add(mapped_matrix_ext[T]&)

>  cdef mapped_matrix_ext[double] *A = new mapped_matrix_ext[double](3, 3,
> 5)

> cdef mapped_matrix_ext[double] *B = new mapped_matrix_ext[double](3, 3, 5)
> cdef mapped_matrix_ext[double] *C

> C = A.add(deref(B))

>  I get the error "Cannot assign type 'mapped_matrix_ext<double> &' to
> 'mapped_matrix_ext<double> *'" for the last line which I think means that I
> need to find the reference of the value returned by the add method. I
> wasn't able to find how to do this in the documentation however (I think
> it's meant to be in "Declaring/Using References" which hasn't yet been
> written). Could someone please help me out?

> Thanks for any help,
> Charanpal

> You have defined "add" to return a reference (mapped_matrix_ext[T]&)
> but are assigning the result to a pointer (mapped_matrix_ext[double]*).
> On Thursday, April 19, 2012 12:25:29 PM UTC-7, csd wrote:

>     Hi all,

>     I am trying to wrap some C++ code in Cython and am having trouble
>     with references. Here is a code snippet:

>     cdef extern from "mapped_matrix_ext.h":

>     cdef cppclass mapped_matrix_ext[T]:

>     mapped_matrix_ext(int, int, int)

>     mapped_matrix_ext[T]& add(mapped_matrix_ext[T]&)

>     cdef mapped_matrix_ext[double] *A = new
>     mapped_matrix_ext[double](3, 3, 5)

>     cdef mapped_matrix_ext[double] *B = new
>     mapped_matrix_ext[double](3, 3, 5)
>     cdef mapped_matrix_ext[double] *C

>     C = A.add(deref(B))

>     I get the error "Cannot assign type 'mapped_matrix_ext<double> &'
>     to 'mapped_matrix_ext<double> *'" for the last line which I think
>     means that I need to find the reference of the value returned by
>     the add method. I wasn't able to find how to do this in the
>     documentation however (I think it's meant to be in
>     "Declaring/Using References" which hasn't yet been written). Could
>     someone please help me out?

>     Thanks for any help,
>     Charanpal