step(func: Callable[P, R]) -> StepFunction[P, R]
step(*, workflow: Type['Workflow'] | None = None, num_workers: int = 4, retry_policy: RetryPolicy | None = None) -> Callable[[Callable[P, R]], StepFunction[P, R]]
step(func: Callable[P, R] | None = None, *, workflow: Type['Workflow'] | None = None, num_workers: int = 4, retry_policy: RetryPolicy | None = None) -> Callable[[Callable[P, R]], StepFunction[P, R]] | StepFunction[P, R]
将一个可调用对象装饰为工作流步骤。
该装饰器会检查函数签名以推断可接受的事件类型、返回的事件类型、可选的 Context 参数（可选择性地包含类型化状态模型），以及通过 typing.Annotated 进行的任何资源注入。
当应用于自由函数时，通过
workflow=MyWorkflow提供工作流类。对于实例方法，关联是自动的。
参数：
| 名称 |
类型 |
描述 |
默认 |
workflow
|
type[工作流] | None
|
用于附加自由函数步骤的工作流类。对于方法而言不是必需的。
|
None
|
num_workers
|
int
|
|
4
|
retry_policy
|
RetryPolicy | None
|
|
None
|
返回：
| 名称 | 类型 |
描述 |
Callable |
Callable[[Callable[P, R]], StepFunction[P, R]] | StepFunction[P, R]
|
|
引发：
示例：
方法步骤：
class MyFlow(Workflow):
@step
async def start(self, ev: StartEvent) -> StopEvent:
return StopEvent(result="done")
自由函数步骤：
class MyWorkflow(Workflow):
pass
@step(workflow=MyWorkflow)
async def generate(ev: StartEvent) -> NextEvent: ...
workflows/decorators.py中的源代码
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152 | def step(
func: Callable[P, R] | None = None,
*,
workflow: Type["Workflow"] | None = None,
num_workers: int = 4,
retry_policy: RetryPolicy | None = None,
) -> Callable[[Callable[P, R]], StepFunction[P, R]] | StepFunction[P, R]:
"""
Decorate a callable to declare it as a workflow step.
The decorator inspects the function signature to infer the accepted event
type, return event types, optional `Context` parameter (optionally with a
typed state model), and any resource injections via `typing.Annotated`.
When applied to free functions, provide the workflow class via
`workflow=MyWorkflow`. For instance methods, the association is automatic.
Args:
workflow (type[Workflow] | None): Workflow class to attach the free
function step to. Not required for methods.
num_workers (int): Number of workers for this step. Defaults to 4.
retry_policy (RetryPolicy | None): Optional retry policy for failures.
Returns:
Callable: The original function, annotated with internal step metadata.
Raises:
WorkflowValidationError: If signature validation fails or when decorating
a free function without specifying `workflow`.
Examples:
Method step:
```python
class MyFlow(Workflow):
@step
async def start(self, ev: StartEvent) -> StopEvent:
return StopEvent(result="done")
```
Free function step:
```python
class MyWorkflow(Workflow):
pass
@step(workflow=MyWorkflow)
async def generate(ev: StartEvent) -> NextEvent: ...
```
"""
def decorator(func: Callable[P, R]) -> StepFunction[P, R]:
if not isinstance(num_workers, int) or num_workers <= 0:
raise WorkflowValidationError(
"num_workers must be an integer greater than 0"
)
func = make_step_function(func, num_workers, retry_policy)
# If this is a free function, call add_step() explicitly.
if is_free_function(func.__qualname__):
if workflow is None:
msg = f"To decorate {func.__name__} please pass a workflow class to the @step decorator."
raise WorkflowValidationError(msg)
workflow.add_step(func)
return func
if func is not None:
# The decorator was used without parentheses, like `@step`
return decorator(func)
return decorator
|