Hello, a newbie question here ... How much of an anti-pattern would be to use the task decorator within the flow definition? I'll try to explain myself ... We are trying Prefect -along other frameworks- as orchestrator for a data analysis pipeline. One big advantage we found in Prefect is that, as advertised, it is super easy to convert existing code into a flow managed by Prefect. It is really almost just a matter of "sprinkle in a few decorators, and go". This is a strong advantage over other frameworks, where the code for the flow definition -and sometimes even the tasks definition-, is very much framework-dependent. Using Prefect, you just have your Python code that would otherwise run as any other code, but with the addition of a few decorators, it will be orchestrated by Prefect. Cool! But here's the catch. I said above almost just a matter of "sprinkle in a few decorators, and go", because as soon as you add the task decorator to your functions, they cannot be called anymore as a normal Python function (at least no without changing the code; I mean, I am aware that you can use

task.fn()

to call a task outside of a flow, but that's exactly the point, that by turning a function into a @task, existing code -e.g. tests- that assumes a normal function will not work anymore). One workaround for that is not to use the @task decorator at the function definition, but only within the flow definition. So I illustrate the idea here with a silly but reproducible example: Let's say we have something like this

def foo():
    return "foo"

def flow():
    foo()

flow() # runs fine from everywhere, but no benefits from orchestrator
foo() # runs fine to try things out interactively or within a pytest function test_foo

And then we introduce Prefect, pretty easy, just add @task and @flow and there you go

from prefect import flow, task

@task
def foo():
    return "foo"

@flow
def flow():
    foo()

flow() # runs fine and you get all the perks of a prefectly orchestrated flow
foo() # but this fails with error "Tasks cannot be run outside of a flow" ¯\_(ツ)_/¯

So my question is how bad an idea is to do something like this:

from prefect import flow, task

# DO NOT DECORATE THIS FN AS A TASK
def foo():
    return "foo"

@flow
def flow():
    # BUT ONLY MAKE IT A TASK WITHIN THE FLOW DEFINITION
    foo_task = task(foo)
    foo_task()

flow() # runs fine
foo() # again, runs fin everywhere

That works, and you can keep using your little foo function everywhere. But not sure if such a thing is an anti-pattern that could come back to bite us later down the line.

i wouldn’t call this an anti pattern! i do this often when i have a function that’s useful in its own right, that i may or may not want to act as a task (or even more fun, if i want to load a function from an import string in a flow and then run that as a task)

Thanks Nate, that's good to hear. To me it seems perfectly fine as well. But since this is our first experience with prefect and I am not familiar with its internals and potential intricacies, I was wondering if that could lead to issues down the line. Also, I don't remember having seen that kind of thing in any of the examples / tutorials.

we have something in the works as far as allowing tasks outside of flows :) but for now that’s a hard requirement (that they must be called inside a flow) there’s no direct downside (besides maybe readability?) associated with avoiding the decorator syntax sugar and wrapping functions dynamically

That's great to hear. We'll keep exploring prefect and how to make the best use of it. Meanwhile just many thanks for a nicely crafted piece of software.👏