When to Tolerate Code Duplication and Avoid Premature DRY Abstractions
The article argues that in early development stages, a small amount of code duplication should be tolerated, warning against premature DRY abstractions that can lead to over‑engineered designs, and advises waiting for genuine common patterns before introducing shared abstractions.
The piece discusses the well‑known DRY (Don’t Repeat Yourself) principle, acknowledging its benefits while cautioning that strict adherence too early can lead to unnecessary abstraction and complexity.
It urges developers to pause and consider whether apparent duplication is truly redundant or merely superficial, as functions that look similar may serve different evolving business contexts.
An illustrative example compares deadline checks for Task and Payment objects: although the code appears identical, the two concepts may diverge, and premature merging could make future changes to payment validation invasive.
The recommendation is to keep behaviors separate until enough common patterns emerge, allowing a modest amount of duplication in the early stages of development while awaiting justified abstraction.
The article also references the YAGNI (You Aren’t Gonna Need It) principle, emphasizing that future requirements are hard to predict and that premature abstraction can be more problematic than manageable duplication.
Original source: https://testing.googleblog.com/2024/05/dont-dry-your-code-prematurely.html
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