class Fiddle::Closure

closure = Class.new(Fiddle::Closure) {
  def call
    10
  end
}.new(Fiddle::TYPE_INT, [])
   #=> #<#<Class:0x0000000150d308>:0x0000000150d240>
func = Fiddle::Function.new(closure, [], Fiddle::TYPE_INT)
   #=> #<Fiddle::Function:0x00000001516e58>
func.call
   #=> 10

static VALUE
initialize(int rbargc, VALUE argv[], VALUE self)
{
    VALUE ret;
    VALUE args;
    VALUE abi;
    fiddle_closure * cl;
    ffi_cif * cif;
    ffi_closure *pcl;
    ffi_status result;
    int i, argc;

    if (2 == rb_scan_args(rbargc, argv, "21", &ret, &args, &abi))
        abi = INT2NUM(FFI_DEFAULT_ABI

    Check_Type(args, T_ARRAY

    argc = RARRAY_LENINT(args

    TypedData_Get_Struct(self, fiddle_closure, &closure_data_type, cl

    cl->argv = (ffi_type **)xcalloc(argc + 1, sizeof(ffi_type *)

    for (i = 0; i < argc; i++) {
        int type = NUM2INT(RARRAY_AREF(args, i)
        cl->argv[i] = INT2FFI_TYPE(type
    }
    cl->argv[argc] = NULL;

    rb_iv_set(self, "@ctype", ret
    rb_iv_set(self, "@args", args

    cif = &cl->cif;
    pcl = cl->pcl;

    result = ffi_prep_cif(cif, NUM2INT(abi), argc,
                INT2FFI_TYPE(NUM2INT(ret)),
                cl->argv

    if (FFI_OK != result)
        rb_raise(rb_eRuntimeError, "error prepping CIF %d", result

#if USE_FFI_CLOSURE_ALLOC
    result = ffi_prep_closure_loc(pcl, cif, callback,
                (void *)self, cl->code
#else
    result = ffi_prep_closure(pcl, cif, callback, (void *)self
    cl->code = (void *)pcl;
    i = mprotect(pcl, sizeof(*pcl), PROT_READ | PROT_EXEC
    if (i) {
        rb_sys_fail("mprotect"
    }
#endif

    if (FFI_OK != result)
        rb_raise(rb_eRuntimeError, "error prepping closure %d", result

    return self;
}

static VALUE
to_i(VALUE self)
{
    fiddle_closure * cl;
    void *code;

    TypedData_Get_Struct(self, fiddle_closure, &closure_data_type, cl

    code = cl->code;

    return PTR2NUM(code
}