Automated Refactoring of Non-Idiomatic Python Code with Pythonic Idioms

Compared to other programming languages (e.g., Java), Python has more idioms to make Python code concise and efficient. Although Pythonic idioms are well accepted in the Python community, Python programmers are often faced with many challenges in using them, for example, being unaware of certain Pythonic idioms or not knowing how to use them properly. Based on an analysis of 7,577 Python repositories on GitHub, we find that non-idiomatic Python code that can be implemented with Pythonic idioms occurs frequently and widely. To assist Python developers in adopting Pythonic idioms, we design and implement an automatic refactoring tool named RIdiom to refactor code with Pythonic idioms. We identify twelve Pythonic idioms by systematically contrasting the abstract syntax grammar of Python and Java. Then we define the syntactic patterns for detecting non-idiomatic code for each Pythonic idiom. Finally, we devise atomic AST-rewriting operations and refactoring steps to refactor non-idiomatic code into idiomatic code. Our approach is evaluated on 1,814 code refactorings, achieving a precision of 0.99 and a recall of 0.87, underscoring its effectiveness. We further evaluate the tool’s utility in helping developers refactor code with Pythonic idioms. A user study involving 14 students demonstrates a 112.9% improvement in correctness and a 35.5% speedup when referring to the tool-generated code pairs. Additionally, the 120 pull requests that refactor non-idiomatic code with Pythonic idioms, submitted to GitHub projects, resulted in 79 responses. Among these, 49 accepted and praised the refactorings, with 42 merging the refactorings into their repositories.