[fix] Fix breaking change in PyLate when loading modules

[tomaarsen]

Resolves #3108

Hello!

Pull Request overview

• Prevent crash when calling get_class_from_dynamic_module with incorrect class_ref.

Details

If the class_ref in _load_module_class_from_ref does not start with sentence_transformers., and it's not a remote module, but e.g. pylate's Dense, then get_class_from_dynamic_module will fail due to a, b = c.split(".") where c has more than 1 dot.

I think the cleanest solution is to ignore the ValueError - as otherwise we risk missing some edge cases if we e.g. expand on the if trust_remote_code ... before the get_class_from_dynamic_module call.

@NohTow I believe you already verified that this solution works, right?

• Tom Aarsen

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sentence_transformers/SentenceTransformer.py:1563

• The comment should be more specific. Suggestion: 'Ignore the error if 1) the file does not exist, or 2) the class_ref does not start with 'sentence_transformers.' or is otherwise incorrectly formatted.'

# Ignore the error if 1) the file does not exist, or 2) the class_ref is not correctly formatted/found

[NohTow]

Hello,
Yes, I can confirm that this solve the issue. I checked the results with exported jina-colbert-v2 and they are identical to the original model.
Thanks!

Small nitpick: the PR does not "prevent calling get_class_from_dynamic_module", it actually calls it but fallback to the other loading method when crashing.

[tomaarsen]

Small nitpick: the PR does not "prevent calling get_class_from_dynamic_module", it actually calls it but fallback to the other loading method when crashing.

Yes, let me update my phrasing. I meant "prevent calling ... from resulting in crash", but it wasn't clear:

Prevent calling get_class_from_dynamic_module with incorrect class_ref resulting in a crash.

• Tom Aarsen