pytorch/torch/csrc/jit/python/opaque_obj.h
angelayi 3be9c86c74 [opaque obj] Initial OpaqueObject (#162660)
A big pain point ppl have with custom ops is that they do not accept arbitrary input/outputs. In this PR we create the concept of an "OpaqueObject" which allows users to pass arbitrary python objects into custom operators.

Some still slightly annoying parts with this implementation:
- The schema of the operator is `__torch__.torch.classes.aten.OpaqueObject` instead of whatever python type
- `@torch.library.custom_op` doesn't work.. yet?

UX:
```python
from torch._library.opaque_object import make_opaque, get_payload

# your custom python class
class OpaqueQueue:
    def __init__(self, queue: list[torch.Tensor], init_tensor_: torch.Tensor) -> None:
        super().__init__()
        self.queue = queue
        self.init_tensor_ = init_tensor_

    def push(self, tensor: torch.Tensor) -> None:
        self.queue.append(tensor)

    def pop(self) -> torch.Tensor:
        if len(self.queue) > 0:
            return self.queue.pop(0)
        return self.init_tensor_

    def size(self) -> int:
        return len(self.queue)

queue = OpaqueQueue([], torch.zeros(3))
obj: torch._C.ScriptObject = make_opaque(queue)

# obj.payload stores a direct reference to this python queue object
self.assertEqual(get_payload(obj), queue)

# This is able to be passed through the dispatcher
torch.ops._TestOpaqueObject.queue_push(obj, torch.ones(3))
self.assertTrue(queue.size(), 1)
```

Authoring a custom op:

```python
lib = torch.library.Library("_TestOpaqueObject", "FRAGMENT")

torch.library.define(
    f"_TestOpaqueObject::queue_push",
    "(__torch__.torch.classes.aten.OpaqueObject a, Tensor b) -> ()",
    tags=torch.Tag.pt2_compliant_tag,
    lib=lib,
)

@torch.library.impl(f"{libname}::queue_push", "CompositeExplicitAutograd", lib=lib)
def push_impl(q: torch._C.ScriptObject, b: torch.Tensor) -> None:
    # We can get the payload directly by get_payload(q)
    queue = get_payload(q)
    assert isinstance(queue, OpaqueQueue)
    queue.push(b)
```

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162660
Approved by: https://github.com/zou3519
2025-09-22 18:30:28 +00:00

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#pragma once
#include <string>
#include <c10/macros/Macros.h>
#include <pybind11/pybind11.h>
#include <pybind11/pytypes.h>
#include <torch/csrc/Export.h>
#include <torch/csrc/utils/pybind.h>
#include <torch/custom_class.h>
namespace torch::jit {
struct OpaqueObject : public CustomClassHolder {
OpaqueObject(py::object payload) : payload_(payload) {}
void setPayload(py::object payload) {
payload_ = payload;
}
py::object getPayload() {
return payload_;
}
py::object payload_;
};
static auto register_opaque_obj_class =
torch::class_<OpaqueObject>("aten", "OpaqueObject");
} // namespace torch::jit