Re: [Swig-user] swig tutorial information sources (long response, sorry) -- I tried these suggestions and they didn't work, follow up questions

[Gibbs, S. <Sol...@sr...>]

I'm sorry my suggestions didn't work out for you. I hoped that they
would be enough to get you started and you'd be able to fill in the
pieces I missed or got wrong.=20

> // From newsgroup
> %typemap(in) struct** STRUCTIN ($&1_type tmp){
>    //**** fixup ****
>    // $&1_type tmp defines a variable tmp with the type of=20
> pointer to $1
>    // $input is the input of the typemap/wrapper function.
>    tmp =3D $input;
>=20
>    // $1 will be the arguement to the C code.
>    $1 =3D *tmp;
> }
> %apply struct** STRUCTIN {SwigSimpleStruct_t** here}
>=20
> %include "SwigSimpleStruct.h"
>=20
> In fact, it would appear that the typemap is never even=20
> applied. If it were, wouldn't the string '//**** fixup ****'=20
> be inserted somewhere inside SwigSimpleStruct_wrap.c? No string there.
>=20
> So what's STRUCTIN? A special variable like INPUT and OUTPUT?=20
> Where does it come from? What is it? Is it documented=20
> anywhere? Does the typemap create it (my guess)?=20

The typemap directive creates a map that matches the fake type struct**
with name STRUCTIN. It is totally specific to the code that's being
written here. It has nothing to do with swig internals.

> What's=20
> %apply do? Why do I have to apply to SwigSimpleStruct_t**.=20
> Why 'here', because the matching is syntactic on the C=20
> function declaration? What if I want this transformation applied
> *only* for the C function SwigSimpleStructCreateHere()? How=20
> do I state that?

The %apply directive tells swig to apply the STUCTIN map for type
struct** to SwigSimpleStruct_t** parametres named "here". So, yes, it
matches the C function declaration. You could define the typemap with
the types for the C function directly too. My preference is to use the
%apply directive; I think it makes the swig interface module easier to
read by explicitly specifying which typemap is used.

If you wanted the typemap applied only to that specific C function, I
would start by moving away from importing the C header file into the
swig module. Copy and paste the declarations. Then you can either rename
the variable you want the typemap applied to to something unique or put
the %apply directive just before the declaration it's to be applied to
and put a %clear directive just after the declaration.
http://swig.sourceforge.net/Doc1.3/Typemaps.html#Typemaps_nn48
=20