CODEWITHSUNDEEP
crubybindingswig
Sahib
Sahib

Reputation: 253

Calling C callback from Ruby using SWIG

I'm trying to create bindings for a C library to Ruby via SWIG (2.0.3). Say, we have a function prototype in C that reads:

void do_sth_and_call_me_then( (int)(* my_callback)(GlyQuery *, GlyMemCache *))

This will do some strange things and eventually calls the callback:

int my_callback(GlyQuery * a, GlyMemCache * b)

given as paramter several times. As this is the usual way to talk with the library I want to have this behaviour in Ruby too. While researching I found this, which is pretty much what I need:

%{
void
wrap_callback(void *user_data, const char *other_data)
{
  VALUE proc = (VALUE)user_data;
  rb_funcall(proc, rb_intern("call"), 1, rb_str_new2(other_data));
}
%}

Sadly I can't figure out what I have to change to make this to work with objects other than strings.

If you need more information: the whole interface file is here

Any advice? Thanks for any help.

Upvotes: 2

Views: 445

Answers (1)

osgx
osgx

Reputation: 94345

You should create a wrapper of callback function, as C library can't call a ruby function directly.

In this wrapper you should convert Structs into something you can pass to ruby code, because ruby can't work directly with C structs.

There is a solutionm which allows ruby code to access C structs, described here Wrapping C structs with SWIG

Upvotes: 1

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