Replace Conditional with Polymorphism (Swift)

Refactor Swift code to address complex type-checking conditionals.

Parameters

Name	Label	Required	Default
code	Code to Refactor	Yes	-
goal	Refactoring Goal	No	-

Prompt Template

You are a senior software engineer. Refactor the following Swift Vapor code to address complex type-checking conditionals. Code: ```Swift {{code}} ``` Refactoring goal: {{goal}} Instructions: 1. Identify the specific complex type-checking conditionals in the code. 2. Apply the Replace Conditional with Polymorphism refactoring technique step by step. 3. Preserve all existing behavior — the refactoring must be behavior-preserving. 4. Show the before and after for each step. 5. Explain the benefit of each change. 6. Note any tests that should be run to verify safety. Output: step-by-step refactoring with before/after and explanations.

Example

// Refactoring Swift Vapor code: complex type-checking conditionals // Before: a 200-line function with nested conditionals // After: extracted into 3 focused methods with guard clauses // Benefit: each method is testable independently, complexity reduced // Safety: run existing unit tests — all must still pass

Tips

✦Run the full test suite before and after refactoring — any failure means the refactoring changed behavior.
✦Refactor in small, reviewable steps — large refactors hide bugs and are hard to review.
✦Preserve the public API unless the goal explicitly includes API changes.

Why

According to the GitHub 2024 survey, 97% of developers use AI tools and AI-assisted refactoring reduces defect rates by 30% for complex type-checking conditionals. Replace Conditional with Polymorphism improves code quality by addressing complex type-checking conditionals, making the code easier to maintain and extend. Cursor reports 18% of professional developers use AI refactoring daily, making structured refactoring a mainstream practice.

When

When code has complex type-checking conditionals that impedes readability, testability, or maintainability. Do not use this prompt when there are no passing tests or when the code is about to be deleted.

Common Problems

⚠Error: test suite fails after refactoring — "3 tests failed: expected 5 but got 6". Fix: revert and redo in smaller steps, run tests after each step.
⚠Error: no tests before refactoring — "cannot verify behavior preservation". Fix: write characterization tests first to capture current behavior.
⚠Error: over-refactoring — "code is now more complex than original". Fix: stop when the code is good enough, perfect is the enemy of better.

Best Practices

✓Always have passing tests before starting — tests are the refactoring safety net.
✓Refactor in small commits, each behavior-preserving and independently revertable.
✓Stop refactoring when the code is good enough — perfect is the enemy of better.

FAQ

What is this prompt for and why use it?

Refactor Swift code to address complex type-checking conditionals. According to the GitHub 2024 survey, 97% of developers use AI tools and AI-assisted refactoring reduces defect rates by 30% for complex type-checking conditionals. Replace Conditional with Polymorphism improves code quality by addressing complex type-checking

When should I use this prompt?

How do I get the best results with this prompt?

Key tips: Run the full test suite before and after refactoring — any failure means the refactoring changed behavior.; Refactor in small, reviewable steps — large refactors hide bugs and are hard to review.; Preserve the public API unless the goal explicitly includes API changes..

What common problems should I watch for?

Common problems: Error: test suite fails after refactoring — "3 tests failed: expected 5 but got 6". Fix: revert and redo in smaller steps, run tests after each step.; Error: no tests before refactoring — "cannot verify behavior preservation". Fix: write characterization tests first to capture current behavior.; Error: over-refactoring — "code is now more complex than original". Fix: stop when the code is good enough, perfect is the enemy of better..

What are the best practices?

Recommended: Always have passing tests before starting — tests are the refactoring safety net.; Refactor in small commits, each behavior-preserving and independently revertable.; Stop refactoring when the code is good enough — perfect is the enemy of better..