Nested structures in Ruby Fiddle

Question

• Is it somehow possible to define nested structure signatures in Ruby's Fiddle lib?
• Or at this point via any other up-to-date library which I'm not familiar with?

It is kind of a desperate question since I've searched through the documentation and Fiddle's code and found no clue about nested structs (although the FFI library was able to do that apparently and Fiddle should be a wrapper for FFI).

Answer 1

How about:

data.c

#include <stdio.h>  struct A {     int a_id; };  struct B {     int b_id;     struct A a_nested; };  void dump_b(struct B* b) {     printf("B.b_id: %d\n", b->b_id);     printf("B.a_nested.a_id: %d\n", b->a_nested.a_id); } 

fiddle.rb

# frozen_string_literal: true  require 'fiddle' require 'fiddle/import'  module Test   extend Fiddle::Importer    dlload './data.dylib'    B = struct [     "int id",     "int a_id"   ]    extern 'void dump_b(struct B*)' end  b = Test::B.malloc  b.id = 123 b.a_id = 13  puts b.id puts b.a_id  Test.dump_b(b) 

or ffi.rb

require 'ffi'  module Test   extend FFI::Library    ffi_lib 'data.dylib'    class A < FFI::Struct     layout :id,  :int   end    class B < FFI::Struct     layout :id,  :int,            :a_nested, A   end    attach_function :dump_b, [:pointer], :void end  a = Test::A.new  a[:id] = 3000  b = Test::B.new  b[:id] = 1000 b[:a_nested] = a  puts b[:id] puts b[:a_nested][:id]  Test.dump_b(b) 

Result

$ gcc -c data.c $ gcc -dynamiclib data.o -o data.dylib $ ruby fiddle.rb 123 13 B.b_id: 123 B.a_nested.a_id: 13 $ ruby ffi.rb 1000 3000 B.b_id: 1000 B.a_nested.a_id: 3000