Re: [Swig-user] Perl C Array Typemaps

[Steven H. <snh...@gm...>]

On Mon, 4 Jun 2007, Gordan Bobic wrote:

> Steven Hirsch wrote:
>
>> You will have more success using the approach I suggested.  If all you
>> want is to get back a wrapped pointer, just declare something like:
>>
>> float *FloatCreate( float *Array ) {
>>   return Array;
>> }
>
> That is exactly what I tried first. But when I try:
> $DataV = MyCLib::FloatCreate(\@Data);
>
> I similarly get:
> TypeError in method 'FloatCreate', argument 1 of type 'float *'

I think you can apply a typemap to one specific function.  Also, I believe 
you must define the typemap before anything that expects to use it.

> Here's the whole of the code I'm using:
> %inline
> %{
> 	float *FloatCreate (float *Array)
>        {
>                return Array;
>        }
> %}
>
> %typemap(in) float *
> {
>        AV *tempav;
>        I32 len;
>        int i;
>        SV  **tv;
>        if (!SvROK($input))
>                croak("Argument $argnum is not a reference.");
>        if (SvTYPE(SvRV($input)) != SVt_PVAV)
>                croak("Argument $argnum is not an array.");
>        tempav = (AV*)SvRV($input);
>        len = av_len(tempav);
>        $1 = (float *) malloc(len * sizeof(float));
>        for (i = 0; i < len; i++)
>        {
>                tv = av_fetch(tempav, i, 0);
>                $1[i] = (float) SvNV(*tv);
>        }
> };
>
> On a separate note, won't this kill pointer passing in any other context
> (i.e. non arrays)? Can a typemap be identified on a pair of values,
> somehow, so that it only triggers if I pass (int, float*)?

Typemaps can (probably) do what you need, but I end up pulling my hair out 
of my head every time I have to code one.  Perhaps you can typedef float* 
to something with a unique name and typemap that?  Something like:

%inline %{

 	typedef float* float_ptr_t;
%}

Then do your typemap thusly:

%typemap(in) float_ptr_t
{
...
};

Finally:

void your_routine ( float_ptr_t arg ) {


Might work.

Can anyone else on the list help?


Steve


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