Dev Tools · 2h ago
Python's lazy evaluation hides refactor bug until AST test catches it
A developer refactored a Python browser automation script, moving a variable into a new function but forgetting to update a residual check. Python's lazy evaluation prevented the NameError from surfacing until a specific execution path ran. The team added an AST-based static analysis test to prevent similar scope-crossing bugs.
Meridian48 take
The story is a niche debugging case study, but the AST test technique is a useful pattern for teams relying on dynamic languages.
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A variable I'd refactored into one function — and kept referencing from another. Python's lazy evaluation hid it, and an AST test finally caught it →
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pythonstatic-analysis