[RFC] Simplify optional package imports in the codebase about lightning-flash

[justusschock]

Yes, that's something I thought of. This might be a good replacement for flash packages, but in lightning we sometimes also have in-code dependencies on these variables, meaning that I would define them again no-matter if we replaced them globally.
I don't know yet, if that's the case for flash as well (it could be for example if the supported models depend on that). So in general I like the idea, in lightning it won't make sense to use this and in flash it depends on the condition I just mentioned :)

[justusschock]

not sure if that really helps, since otherwise we may have to mock them with None in some cases.

[akihironitta]

@justusschock Thank you for your feedback. Do you mean like this in pytorch_lightning/loggers/wandb?

except ImportError:
    wandb, Run = None, None

It will still be possible in that case, too, by:

if not cm.is_successful():
    wandb, Run = None, None

[carmocca]

I like it. We could call it OptionalImport.

Some questions:

• Can you do more than one import inside the context manager? What if they all fail?
• How do you plan to pass the install it with 'pip install lightning-flash[image]' message?

[kaushikb11]

Hi @akihironitta, do you want to give it a try?

[akihironitta]

Sorry for the delay, I missed your message.

Can you do more than one import inside the context manager? What if they all fail?

Yes, but in case of multiple packages like the below case, if import kornia fails, import transformers will be skipped, so we need to split the import statements per individual package:

with try_import() as _import:
    import kornia        # if kornia not found
    import transformers  # this line will be skipped

# so, it needs to be divided
with try_import() as _import_kornia:
    import kornia
with try_import() as _import_transformers:
    import transformers

How do you plan to pass the install it with 'pip install lightning-flash[image]' message?

Currently, I came up with nothing except for hard-coding in flash/utils/imports.py as below. I thought of parsing requirements/*.txt, but packages can have different names than their pypi names. e.g. PIL for Pillow.

_extras = {
    "image": ["torchvision", "PIL", "kornia", ...],
    ...
}

---

I was thinking about this issue again, and I'm now not sure if my suggestion is reasonable enough because my suggestion itself cannot handle version checks...

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.