WPS412: Flask App Factory Pattern Incompatibility

[elpapi42]

Rule request

Thesis

Change WPS412 to accept logic inside init.py files.

Reasoning

Flask App Factory Pattern depend on the main package _init.py for define the create_app() function, this is the natural location for this type of logic. Check this example Flask project's init.py

Maybe this can be a problem too for when a subpackage if defined, and is natural to expose its internals in the init.py for avoid boiler plate, for example:

Change

from deepbay.denseblock import DenseBlock

To

from deepbay import DenseBlock

If my reasoning is not good enough, feedback will be appreciated, thanks!

[elpapi42]

I can mention this Flask Mega-Tutorial as reference and backup for my suggestion.

[sobolevn]

Why not application/app.py?

[elpapi42]

@sobolevn that sounds legit, but dont cover the other case, reduce boilerplate when importing libraries

Change

from deepbay.denseblock import DenseBlock

To

from deepbay import DenseBlock

It dont cover a subpackage case, for example, a Flask Blueprint Package, where the "Package" its a representation of the Blueprint, and like so, sounds good to init the Blueprint required stuff in its init.py. Following your solution this can be solved with a blueprint.py in each Blueprint Subpackage, and that is an overkill from my point of view. this also means that for import the created Blueprint we must do:

from application.<blueprint-name>.blueprint import <blueprint-name>_bp

Instead of just

from application.<blueprint-name> import <blueprint-name>_bp

[sobolevn]

In our rules __init__.py only solves the compatibility issues. That's why it is configured via --i-dont-control-code setting.

And namespaces are always a great idea! We need more of those!

[elpapi42]

Got it @sobolevn. can you give me some insights or recommendations about how i can refactor my code?

Go for the application..bluepirnt.py for init the blueprint related stuff?

In other python applications, should i keep the init.py for expose the subpackage internals more directly to the namespace?

Just looking for a clear path to resolve this, thanks in advance!

[sobolevn]

Just rename your __init__.py to blueprint.py (or whatever suits you best) and create a new empty __init__.py

Does this solve your problem?

[elpapi42]

just one last question: What i must do with the imports in the init.py:

1. get rid of them and let the imports be:

from deepbay.denseblock import DenseBlock

2. Keep the imports and do:

from deepbay import DenseBlock

In the last case, WPS will still mark unused imports warning.

What approach you recommend to me?

Thanks for your time, sorry for pick it up a bit.

[sobolevn]

I always keeps imports out of __init__.py - it allows to match files and modules as 1-to-1 entities.
Helpful and readable!

[sobolevn]

I am going to close this as solved, if you have any other questions - please, feel free to ask!
You can reopen this one or create new issues if you have other questions.