Re: help with typemap

On Wed, Dec 23, 2020 at 11:52 AM William S Fulton
<[email protected]> wrote:
>
> Looks like you are using it in an overloaded C++ function. You need to also provide a 'typecheck' typemap in addition to the 'in' typemap.
>>
>>

Thanks for the help William. I looked for examples of how to create a
typecheck for a "const unsigned char * " and unfortunately I didn't
find much. So I copied an example from the SWIG docs and used
SWIG_TYPECHECK_UINT8_PTR.

%typemap(typecheck, precedence=SWIG_TYPECHECK_UINT8_PTR, noblock=1) SWIGTYPE * {
 void *vptr = 0;
 int res = SWIG_ConvertPtr($input, &vptr, $1_descriptor, 0);
 $1 = SWIG_IsOK(res) ? 1 : 0;
}

%typemap(in) const unsigned char *buffer {   //used buffer instead of data
...
}

I don't know if the typecheck is correct. However, it did not work. So
I looked more closely at the overloaded C++ header for the function.

 Fl_JPEG_Image(const char *filename);
 Fl_JPEG_Image(const char *name, const unsigned char *data); // this
is the function

Then I noticed I used the variable "buffer" not "data" in typemap(in)
(see above). So I simply changed the var name to data

%typemap(in) const unsigned char *data {  //used data instead of buffer

and it worked, even without the typecheck!!
I found this in the swig docs
http://www.swig.org/Doc4.0/Typemaps.html#Typemaps_nn5
"In addition to tracking typenames, typemaps may also be specialized
to match against a specific argument name"

So I solved my issue, but is my typecheck correct? If not, how should I fix it?