Feat: support reusable instance of ModelCheckpoint

[ScarWar]

What does this PR do?

Fixes cross-validation folds checkpoint saving behavior

I'm using the great library https://github.com/SkafteNicki/pl_crossvalidate to cross validate in my project. The library is overriding some of the internal behavior of the trainer and the logs directory.

Expected behavior

When new fold is created, the checkpoint path should be changed to the new directory

Current behavior

The checkpoint path is resolved once during the first fold then it is short circuited and therefore never resolving to the new fold directory.

Proposed fix

New variable to save whether the dirpath parameter was passed by the user or was resolved from logger

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Fixes #20092

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📚 Documentation preview 📚: https://pytorch-lightning--20202.org.readthedocs.build/en/20202/

[Borda]

@ScarWar could you please add a test for this case? 🦩

[ScarWar]

Okay, I will add a test case for this soon. I will keep you updated on my progress. Thanks, Ariel

…

On Mon, 7 Apr 2025 at 14:48, Jirka Borovec ***@***.***> wrote: ***@***.**** commented on this pull request. could we pls add a test? — Reply to this email directly, view it on GitHub <#20202 (review)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAYF6VN5HI75PU5L7673OQL2YJQZVAVCNFSM6AAAAABMRVKY6WVHI2DSMVQWIX3LMV43YUDVNRWFEZLROVSXG5CSMV3GSZLXHMZDONBWGUZTIMZVGM> . You are receiving this because you were mentioned.Message ID: ***@***.***>

-- בכבוד רב, אריאל

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[Borda]

Okay, I will add a test case for this soon. I will keep you updated on my

hi, still about to add tests? 🐿️