Move `_*_AVAILABLE` checks to their respective files.

[carmocca]

Proposed refactor

Move all the variables defined here that are only used in one file
https://github.com/PyTorchLightning/pytorch-lightning/blob/1e36cffbca3f92855d82907370544fade1656da6/pytorch_lightning/utilities/imports.py#L98-L134
to their respective files.

Motivation

This encapsulates code and avoids clutter from the utilities.

Pitch

Move:

https://github.com/Lightning-AI/lightning/blob/50fd12f841bc10ec093e80d0acf3e3b51cd927fe/src/pytorch_lightning/utilities/imports.py#L28-L51

To the files that use them.

The rest I don't think should be moved.

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cc @Borda

[Borda]

@carmocca could you elaborate more on why this is needed?
I would say having import change in one place makes it easier to find and this imports is a primitive without any dependency so there is no risk of cyclic imports compared to your proposal...

[carmocca]

My point is that if one of these primitives is used in only one file, then it should be defined there. For example _JSONARGPARSE_AVAILABLE is only used the CLI:

$ grep -iIRn "_JSONARGPARSE_AVAILABLE" pytorch_lightning/
pytorch_lightning//utilities/__init__.py:44:    _JSONARGPARSE_AVAILABLE,
pytorch_lightning//utilities/imports.py:108:_JSONARGPARSE_AVAILABLE = _package_available("jsonargparse") and _compare_version("jsonargparse", operator.ge, "4.0.0")
pytorch_lightning//utilities/cli.py:32:from pytorch_lightning.utilities.imports import _JSONARGPARSE_AVAILABLE
pytorch_lightning//utilities/cli.py:37:if _JSONARGPARSE_AVAILABLE:
pytorch_lightning//utilities/cli.py:131:        if not _JSONARGPARSE_AVAILABLE

Moving it means we contain all the CLI-related logic into a single place instead of leaving "breadcrumbs" in our utilities. The utilities module is slowly becoming a "dumping ground" for random pieces of code when some of those pieces actually have a logical place to be.

Also, as a naive user, I would first look for this in the LightningCLI code than in a generic utility module.

The same argument can be applied to the other variables mentioned in the top post.

[stale]

This issue has been automatically marked as stale because it hasn't had any recent activity. This issue will be closed in 7 days if no further activity occurs. Thank you for your contributions, Pytorch Lightning Team!