initialize_copy

static VALUE
generator_init_copy(VALUE obj, VALUE orig)
{
    struct generator *ptr0, *ptr1;

    ptr0 = generator_ptr(orig);

    TypedData_Get_Struct(obj, struct generator, &generator_data_type, ptr1);

    if (!ptr1) {
        rb_raise(rb_eArgError, "unallocated generator");
    }

    ptr1->proc = ptr0->proc;

    return obj;
}