Prevent variable nullification on later imports#120
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m-dzianishchyts wants to merge 2 commits intodflib:mainfrom
Open
Prevent variable nullification on later imports#120m-dzianishchyts wants to merge 2 commits intodflib:mainfrom
m-dzianishchyts wants to merge 2 commits intodflib:mainfrom
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What does this PR do?
Fixes #119.
Details
When JShell needs to recompile an earlier snippet due to a later snippet affecting its type context (e.g., new wildcard imports), it calls
ExecutionControl.redefine()to hot-swap the wrapper class bytecode. The inheritedDirectExecutionControl.redefine()unconditionally throwsNotImplementedException. JShell then falls back to installing a new wrapper class without re-running the initializer, silently zeroing the static field that backs the user's variable.We can acknowledge the redefinition and only update the loader's bytecode cache. The already-loaded class stays in place, its static fields are preserved. Subsequent snippets are compiled against the recompiled wrapper's signature, which for import-driven recompilations is equivalent to the original, so field and method resolution keeps working against the existing loaded class.
Testing
Integration test reproduces the bug in a single-cell Jupyter execution. Passes with the fix.