Re: [Swig-user] Python lists typemapped to C arrays

[Marcelo M. <mm...@ac...>]

Robert Jones wrote:

> Hi All - can any of you generous souls give me a hint on this one?
>
> I am ultimately trying to call the windows function
>
> long WaitForMultipleObjects(
>     long nCount,
>     HANDLE *lpHandles,
>     int bWaitAll,
>     long dwMilliseconds
>     );
>
> (Only the first two arguments matter for the moment). To provide
> the HANDLEs I have a Python list. I know I have the list properly
> populated because I have written this
>
> void writeHandle( HANDLE h ) {
>     printf( "HANDLE -> %0x\n", h );
>     }
>
> which I have called with this Python code
>
>     for obj in osWaitObjs:
>         writeHandle( obj )
>
> and which prints out exactly the values I am expecting.
> Now, to call the big function with my list I have written this
> typemap
>
> %typemap ( in ) ( long nCount, HANDLE * lpHandles ) {
>     int i;
>     printf( "typemap (in)( long nCount, HANDLE * lpHandles )\n" );
>     if ( ! PyList_Check( $input ) ) {
>         PyErr_SetString( PyExc_ValueError, "Expecting a list" );
>         return NULL;
>     }
>     $1 = PyList_Size( $input );
>     $2 = ( HANDLE * ) malloc( ( $1 + 1 ) * sizeof( HANDLE ) );
>     printf( "List(" );
>     for ( i = 0; i < $1; i ++ ) {
>         PyObject * obj = PyList_GetItem( $input, i );
>         $2[ i ] = ( HANDLE ) PyInt_AsLong( obj );
>         printf( "%0x, ", $2[ i ] );
>     }
>     $2[ i ] = 0;
>     printf( ")\n" );
> }
>
> which includes lots of debugging printf's. Unfortunately the values 
> that result
> from this conversion are not the values of the HANDLEs. HANDLE is 
> ultimately
> defined as a void*. I'm pretty sure my typemap is not right, but I'm 
> not sure how.
>
> Cheers, Rob.

If HANDLE is a void *, then you can't use PyInt_AsLong, you shoud try

  SWIG_ConvertPtr

instead. See the void.swg file in Lib/typemaps (CVS version) for more 
details.

Marcelo