chore!: removing deadcode

[davidsbatista]

Related Issues

• partly fixes https://github.com/deepset-ai/haystack-private/issues/450

Proposed Changes:

• serialize_class_instance/deserialize_class_instance in utils/base_serialization.py are dead code — not exported from haystack.utils, and no caller anywhere in the codebase besides their own unit tests.

How did you test it?

• Ran the full tests, all pass. Grepped the whole repo for any remaining reference to either function, none found.

Checklist

• I have read the contributors guidelines and the code of conduct.
• I have updated the related issue with new insights and changes.
• I have added unit tests and updated the docstrings.
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test: and added ! in case the PR includes breaking changes.
• I have documented my code.
• I have added a release note file, following the contributors guidelines.
• I have run pre-commit hooks and fixed any issue.

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
haystack-docs	Ignored	Preview	Jul 8, 2026 1:33pm

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
haystack/utils
base_serialization.py
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[julian-risch]

Looks good to me in general but there are two integrations that use this code and we should update them before making changes in Haystack: docling and langfuse
https://github.com/search?q=org%3Adeepset-ai+serialize_class_instance+language%3APython&type=code&l=Python

https://github.com/search?q=org%3Adeepset-ai+deserialize_class_instance+language%3APython&type=code

If possible, we should make changes in the integrations in a way that the new releases of integrations are still compatible with Haystack 2.x

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

[davidsbatista]

Related PRs:

• fix: docling stop relying on haystack.utils.base_serialization helpers haystack-core-integrations#3562
• fix(langfuse): stop relying on haystack.utils.base_serialization helpers haystack-core-integrations#3563

[julian-risch]

Looks good to me. It's a breaking change so it's fair that we have an upgrade section in release notes. Good that the two integrations were updated.