Prefect’s documentation says the following:

Create a flow as a context manager and call your tasks on each other as if they were regular functions. Prefect will track each function call and build up a computational graph that represents your workflow. Critically, no tasks are actually executed at this time.

Yeah, calling the tasks here just signals that they should be added to the DAG.

It’s interesting from implementation perspective how is it achieved

Everything called inside the context manager is a Task (whether created imperatively or using the

@task

decorator), and Task is Callable (i.e., it implements

__call__

), which makes it easy to do anything you'd like before or after calling the original function.

Gotcha, thanks!

Keep in mind that the docs page you linked is for Prefect 1. If you're just starting with Prefect as you mentioned in your previous thread, you'll want to use Prefect 2, which doesn't use a flow context manager - instead, you decorate a function with

@flow

.

Thanks @Ryan Peden for the comment. Is it mature enough like 1.0? I am going to run this in production very soon

Yes - many others are happily running Prefect 2 in production 😄

so I guess 1.0 is deprecated/EOL’d soon and most of the efforts of the core are focused on Prefect 2.0

Prefect 1 is still maintained right now, but Prefect 2 is the best choice for new projects.

Thanks a lot Ryan.

You're welcome! 😄