AI Prompt for Removing Duplication

Eliminate code duplication with this AI prompt: find the shared core, extract a parameterized abstraction, and keep each caller's behavior intact.

The prompt

Role: You are a refactoring expert who eliminates duplication with the RIGHT abstraction — not the first one that comes to mind.

Context: Language: [LANGUAGE]. The duplicated code: [CODE_COPIES]. Scope: [SCOPE].

Task: 1) Identify what is truly common vs what varies between the copies. 2) Propose the abstraction (function with parameters, strategy, template method, config-driven — choose the simplest that fits) and JUSTIFY why this shape and not a simpler/duplicated alternative. 3) Show the refactored code: the abstraction plus all call sites updated. 4) Verify: explain how each original copy's behavior is preserved. 5) Warn where abstraction would be WRONG — copies that look similar but represent different concepts.

Format: Common-vs-varying analysis, then the proposed abstraction with justification, then refactored code, then the behavior verification, then the do-not-abstract warning.

Constraints: Follow the Rule of Three — do not abstract two slightly-similar copies prematurely. The abstraction must be simpler to understand than the duplication it replaces.

Variables to fill in

Replace each [variable] in the prompt with your own details:

[LANGUAGE] [CODE_COPIES] [SCOPE]

Example input

LANGUAGE=JavaScript, CODE=3 near-identical form-validation blocks for login, signup, checkout, STRATEGY=shared validator with config, SCOPE=these 3 only

How to use this prompt

Show all the copies — the AI needs to see the variations to design the right abstraction. Scope the refactor; 'all duplication everywhere' is a trap.

Tips for the best results

Ask 'what varies' first — the varying parts design the parameters.
Heed the do-not-abstract warning; wrong abstractions are worse than duplication.
After refactoring, ask for a test proving all original behaviors still hold.

Frequently asked questions

What if the copies differ slightly?

It extracts the shared core and parameterizes the differences — then warns you where the copies have already diverged.

What is the Rule of Three?

Wait for three duplications before abstracting. Two similar copies often diverge; the third reveals the true common shape. The prompt enforces this discipline.

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