# Use a class defined in a detached ray actor

**URL:** <https://discuss.ray.io/t/use-a-class-defined-in-a-detached-ray-actor/21560>\
**Category:** Ray Core\
**Created:** [January 22, 2025, 6:03pm UTC](https://discuss.ray.io/t/use-a-class-defined-in-a-detached-ray-actor/21560 "2025-01-22T18:03:41Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Calab](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/calab/32/5977_2.png) [@Calab](https://discuss.ray.io/u/Calab)\
**Post date:** [January 22, 2025, 6:03pm UTC](https://discuss.ray.io/t/use-a-class-defined-in-a-detached-ray-actor/21560/1 "2025-01-22T18:03:41Z")

</div>

**How severe does this issue affect your experience of using Ray?**

- High: It blocks me to complete my task.

I have a detached ray actor running. Within that class I have another class defined. I want to use that class outside of the actor to create an object. The objects I create will later get passed back to the actor in a remote() call.

The following code does not work, but should give you an idea of what I’m trying to accomplish.

How can I accomplish this, or is it even possible?

```auto
import ray
import os

# Iniialize ray
if not ray.is_initialized():
    ray.init(namespace="LAB",
             ignore_reinit_error=True)

@ray.remote
class RayClass:

    class Person:
        def __init__ (self, name, age=None):
            self.name = name
            self.age = age

    def __init__ (self):
        pass

    def hello(self, person):
        print(f"Hello {person.name}")

# Start a detached actor we can use for testing.
# In reality, the actor would have been started elsewhere
# and we would just be getting it
the_actor = RayClass.options(name="class_test",
                            lifetime="detached",
                           ).remote()

# Get the detached actor
my_actor = ray.get_actor("class_test")

# Create a person object based on the class defined in our actor
# This is where my problem is
my_person = my_actor.Person("Bob", 22)

# Do the class function to see that it's working
# Most likely will be no output as it's running in a ray instance
my_actor.hello.remote(my_person)

# Show the name of the person
print(my_person.name)

ray.kill(ray.get_actor("class_test", namespace="LAB"))

```

---

<div class="post-metadata">

**Author:** ![ruisearch42](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/ruisearch42/32/6012_2.png) [@ruisearch42](https://discuss.ray.io/u/ruisearch42)\
**Post date:** [January 22, 2025, 7:15pm UTC](https://discuss.ray.io/t/use-a-class-defined-in-a-detached-ray-actor/21560/2 "2025-01-22T19:15:50Z")

</div>

Hi @Calab , what failure did you see, can you post the stack trace?

---

<div class="post-metadata">

**Author:** ![Calab](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/calab/32/5977_2.png) [@Calab](https://discuss.ray.io/u/Calab)\
**Post date:** [January 22, 2025, 7:27pm UTC](https://discuss.ray.io/t/use-a-class-defined-in-a-detached-ray-actor/21560/3 "2025-01-22T19:27:07Z")

</div>

Here is the trace:

```auto
2025-01-22 19:24:34,022 INFO worker.py:1612 -- Started a local Ray instance. View the dashboard at 127.0.0.1:8265 
Traceback (most recent call last):
  File "/home/steve/WorkArea/ray_test.py", line 35, in <module>
    my_person = my_actor.Person("Bob", 22)
  File "/opt/conda/lib/python3.10/site-packages/ray/actor.py", line 1201, in __getattr__
    raise AttributeError(
AttributeError: 'ActorHandle' object has no attribute 'Person'

```

---

<div class="post-metadata">

**Author:** ![Calab](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/calab/32/5977_2.png) [@Calab](https://discuss.ray.io/u/Calab)\
**Post date:** [January 24, 2025, 3:14pm UTC](https://discuss.ray.io/t/use-a-class-defined-in-a-detached-ray-actor/21560/4 "2025-01-24T15:14:19Z")

</div>

I’ve built a workaround… I doubt that this is the best way to accomplish what I want, but it works.

```auto
import ray
import os

# Iniialize ray
if not ray.is_initialized():
    ray.init(namespace="LAB",
             ignore_reinit_error=True)

@ray.remote
class RayClass:

    class Person:
        def __init__ (self, name, age=None):
            self.name = name
            self.age = age

    def __init__ (self):
        pass

    def hello(self, person):
        print(f"Hello {person.name}")

    ##### Added function to generate a Person object ##########
    def build_person(self, name, age=None):
        return self.Person(name, age)

# Start a detached actor we can use for testing.
# In reality, the actor would have been started elsewhere
# and we would just be getting it
the_actor = RayClass.options(name="class_test",
                            lifetime="detached",
                           ).remote()

# Get the detached actor
my_actor = ray.get_actor("class_test")

# Create a person object based on the class defined in our actor
# This is where my problem is
# my_person = my_actor.Person("Bob", 22)

##### My workaround ##########
my_person = ray.get(my_actor.build_person.remote("Bob", 22))

# Do the class function to see that it's working
# Most likely will be no output as it's running in a ray instance
my_actor.hello.remote(my_person)

# Show the name of the person
print(my_person.name)

ray.kill(ray.get_actor("class_test", namespace="LAB"))

```

---

<div class="post-metadata">

**Author:** ![ruisearch42](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/ruisearch42/32/6012_2.png) [@ruisearch42](https://discuss.ray.io/u/ruisearch42)\
**Post date:** [January 25, 2025, 7:27pm UTC](https://discuss.ray.io/t/use-a-class-defined-in-a-detached-ray-actor/21560/5 "2025-01-25T19:27:18Z")

</div>

Hi @Calab , the original failure you saw is because `my_actor` is an `ActorHandle` and is not supposed to be used to get its internal class that way. The workaround looks good, but I will take a look if there is a better way.

BTW, so moving `Person` out of `RayClass` is not an option?

---

<div class="post-metadata">

**Author:** ![Calab](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/calab/32/5977_2.png) [@Calab](https://discuss.ray.io/u/Calab)\
**Post date:** [January 26, 2025, 2:17am UTC](https://discuss.ray.io/t/use-a-class-defined-in-a-detached-ray-actor/21560/6 "2025-01-26T02:17:30Z")

</div>

> [@ruisearch42](#):
>
> BTW, so moving `Person` out of `RayClass` is not an option?

I don’t think so. There will be several other scripts that use this actor and maintaining `Person` outside of the actor would be a headache.