Issues with calling a rust library from Python

First off I want to say thank you for SWIG.  The project is fantastic and
so far the documentation has been great.  I have a feeling I'm just missing
one small thing and haven't been able to find it in the docs yet.

I'm working on building a library in rust that I think would be extremely
useful in other languages.  I would like to expose this functionality with
idiomatic bindings to as many languages as possible with as little effort
as I can get away with.  Obviously SWIG is a great choice for this project.


I'm using a project called safer_ffi to produce the C interface to the rust
library.  It removes a lot of the error prone boiler plate on the rust side
away from me but also limits my options on exactly what the C interface
looks like.  Currently it represents strings with this C type:

typedef struct {
> uint8_t * ptr;
> size_t len;
> } slice_boxed_uint8_t;
>

I can't for the life of me set the ptr member of the struct without causing
a TypeError in python.  My interface file is simply:

> %module swig_example
> %{
> /* Includes the header in the wrapper code */
> #include "swig_example.h"
> %}
>
> %include "stdint.i"
> %include "cstring.i"
>
> /* Parse the header file to generate wrappers */
> %include "swig_example.h"
>

and I try and set up the struct with the following python:

> def _str_to_slice(input: str) -> slice_boxed_uint8_t:
>     slice = slice_boxed_uint8_t()
>     slice.ptr = input
>     slice.len = len(input)
>     return slice
>

which produces the following error "TypeError: in method
'slice_boxed_uint8_t_ptr_set', argument 2 of type 'uint8_t *'".  I have
tried all sorts of combinations of how to invoke it and how to generate the
bindings.  I've been walking through the generated C code but haven't found
the issue yet. It looks like it understands that this pointer is a char*
but isn't making the connection that it is okay to use as a uint8_t*.  I
might have misunderstood some of the generated C code, I'm still not very
deep on walking through that yet.


I know I might be missing some important context in this email so the code
can be found here: https://github.com/stusmall/python_ffi  The README.md
points out to find all relevant files, reasoning on how things are set up
and I checked in the SWIG generated c and python files.  This project is
the smallest subset of my original project I could make to this easier to
troubleshoot

Huge thank you to any help that anyone can provide!

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