initialize_copy

static VALUE
enum_chain_init_copy(VALUE obj, VALUE orig)
{
    struct enum_chain *ptr0, *ptr1;

    if (!OBJ_INIT_COPY(obj, orig)) return obj;
    ptr0 = enum_chain_ptr(orig);

    TypedData_Get_Struct(obj, struct enum_chain, &enum_chain_data_type, ptr1);

    if (!ptr1) rb_raise(rb_eArgError, "unallocated chain");

    ptr1->enums = ptr0->enums;
    ptr1->pos = ptr0->pos;

    return obj;
}