Fix clone() to update parent references on cloned children#443
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MaxGhenis merged 2 commits intoPolicyEngine:masterfrom Mar 10, 2026
Merged
Fix clone() to update parent references on cloned children#443MaxGhenis merged 2 commits intoPolicyEngine:masterfrom
MaxGhenis merged 2 commits intoPolicyEngine:masterfrom
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After cloning a ParameterNode, each child's `parent` still pointed to the original tree. This meant parameter.update() called clear_parent_cache() on the original parent, not the clone, leaving stale cached values in the cloned tree. This caused silent null returns for NJ reform calculations on the API, where clone() + parameter.update() is used instead of Reform.from_dict(). Fixes PolicyEngine#442 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
clear_parent_cache only cleared self._at_instant_cache inside the `if self.parent is not None` block, so root nodes (parent=None) never had their cache cleared. Move the clear() before the conditional so all nodes in the chain are invalidated. Confirmed: test_clone_update_invalidates_cloned_cache fails without this fix and passes with it. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #443 +/- ##
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+ Coverage 82.51% 82.92% +0.40%
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Files 202 202
Lines 10634 10660 +26
Branches 1069 1071 +2
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+ Hits 8775 8840 +65
+ Misses 1583 1536 -47
- Partials 276 284 +8 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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Summary
ParameterNode.clone()to setchild.parent = cloneafter cloning childrenParameterScale.clone()to setbracket.parent = cloneafter cloning bracketsAfter cloning, each child's
parentstill pointed to the original tree. This meantparameter.update()calledclear_parent_cache()on the original parent instead of the clone, leaving stale cached values in the cloned tree.This is the root cause of silent null returns for NJ reform calculations on the API, where
clone()+parameter.update()is used instead ofReform.from_dict().Fixes #442
Test plan
test_clone_parent_references— verifies cloned children reference the cloned parenttest_clone_scale_parent_references— verifies cloned scale brackets reference the cloned scaletest_clone_update_invalidates_cloned_cache— verifiesparameter.update()on a cloned tree invalidates the clone's cache (not the original's)🤖 Generated with Claude Code