# tensorplay.nn.attention.register_flash_attention_impl

Source: https://www.tensorplay.cn/docs/generated/tensorplay.nn.attention.register_flash_attention_impl.html

```python
tensorplay.nn.attention.register_flash_attention_impl(impl: str | Literal['FA3', 'FA4'], *, register_fn: Callable[[...], FlashAttentionHandle | None]) → None
```

Register the callable that activates a flash attention impl.

> **Note**
>
> This function is intended for SDPA backend providers to register their implementations. End users should use activate_flash_attention_impl() to activate a registered implementation.

Parameters:

- impl – Implementation identifier (e.g., "FA4").

- register_fn – Callable that performs the actual dispatcher registration. This function will be invoked by [activate_flash_attention_impl()](/docs/generated/tensorplay.nn.attention.activate_flash_attention_impl.html#tensorplay.nn.attention.activate_flash_attention_impl) and should register custom kernels with the dispatcher. It may optionally return a handle implementing FlashAttentionHandle to keep any necessary state alive.

Example

```
>>> def my_impl_register(module_path: str = "my_flash_impl"):
...     # Register custom kernels with the dispatcher
...     pass
>>> register_flash_attention_impl(
...     "MyImpl", register_fn=my_impl_register
... )
```