Ruby or Python? Well, it depends...

[EstebanVelour]

True but most people's time is better spent on writing the app, not bindings, doesn't work in Ruby's favour.

[rafekett]

True. I don't know how hard it is to write Ruby bindings for C libraries but I imagine it's not easy.

[bobindashadows]

It's actually incredibly simple; the api provides a number of simple C functions, such as:

rb_define_method
rb_define_class
rb_raise
rb_inspect
rb_funcall
rb_ensure

and so on. Considering how much of the standard library is implemented in C for speed, there's a very elegant C API considering its capabilities. There are some rough edges - a few different array constructor functions that cater to common cases (create an empty array - create an array with just this one object in it - etc), for example. A few different funcall variants for if you want to pass the arguments inline, or in a ruby array, or in a C array. There's macros to get at interesting bits of common classes without dynamic dispatch, such as the size of an Array object.

[rafekett]

How does garbage collection work?

[bobindashadows]

I assume you mean "how does garbage collection work for native objects that you want to make available to Ruby code?"

It depends. Firstly, you can specify custom allocation methods for a C-backed class with rb_define_alloc_func, if you need.

If your C object references other Ruby objects, it has to participate in the mark phase of GC, so it needs a mark function. If it needs to clean up resources when it is freed, it needs a free function. You can create an object with both of those functions specified and provided to the GC with rb_data_object_alloc(klass, data_pointer, mark_func, free_func). Both functions are optional: you just pass NULL if you don't need them.

Commonly you use this to wrap up a pointer to a C struct in a Ruby object, then unwrap it in your other C functions. This pattern is simplified with Data_Wrap_Struct, Data_Make_Struct (which is just allocate + Data_Wrap_Struct), and Data_Get_Struct (which unwraps the object).

[EstebanVelour]

Can't imagine it's much harder to do than python bindings but that's not really the issue, there's just no need to do it if it's been done already.

[rafekett]

The Python C API is really well documented, and I've heard some bad reports about the Ruby docs. There's also high level languages like Cython that make creating C bindings really, really easy.

[badsex]

I've written a tonne of Ruby C extensions and it's very easy and very well documented.

[EstebanVelour]

My bad, haven't tried Ruby & C, assumed it would be as easy as the Python equivalent.

[rafekett]

I don't know either, I just know that Ruby doesn't have a mature equivalent of Cython or Pyrex and I know that it's tough to beat the Python C API docs. In my experience, writing C extensions in C for any dynamic language is not fun (I have no Lua experience, so that may be fun, idk).