C# Refactoring Skill
Systematically refactors C# code to improve maintainability, readability, and adherence to best practices.
Arguments
$ARGUMENTS[0]: Target file path (optional, will scan for .cs files if not provided)$ARGUMENTS[1]: Refactor type (optional):solid,pattern,modern,extract,all
Execution Steps
Step 1: Identify Target
If no file specified ($ARGUMENTS[0] is empty):
- Scan for recently modified
.csfiles - Ask user to select target file(s)
Step 2: Analyze Code
Read and analyze the target code for refactoring opportunities.
Step 3: Apply Refactoring
Based on $ARGUMENTS[1] or analyze all categories:
Refactoring Categories
SOLID Refactoring (solid)
| Violation | Refactoring |
|---|---|
| SRP | Extract class, Split responsibilities |
| OCP | Introduce Strategy/Template Method pattern |
| LSP | Fix inheritance hierarchy, Use composition |
| ISP | Split interface into smaller ones |
| DIP | Extract interface, Inject dependencies |
Pattern Introduction (pattern)
| Code Smell | Suggested Pattern |
|---|---|
| Complex object creation | Builder, Factory Method |
| Multiple conditionals on type | Strategy, State |
| Global state access | Singleton (cautiously), DI |
| Complex subsystem | Facade |
| Tree/composite structures | Composite |
| Adding features dynamically | Decorator |
| Request handling chain | Chain of Responsibility |
Modern C# Syntax (modern)
| Old Syntax | Modern Alternative |
|---|---|
| Constructor + field assignment | Primary constructor |
new List<T> { ... } | Collection expressions [...] |
| Multiple null checks | Pattern matching, ?., ?? |
| Verbose switch statements | Switch expressions |
| Manual INPC implementation | [ObservableProperty] (CommunityToolkit.Mvvm) |
| Mutable properties (non-MVVM) | required, init for immutability |
| Class for simple data | Record types |
| Traditional foreach | LINQ where appropriate |
Extract Refactoring (extract)
- Extract Method: Long methods → smaller, focused methods
- Extract Class: Large class → multiple cohesive classes
- Extract Interface: Concrete dependencies → interface abstraction
- Extract Base Class: Duplicate code → shared base
- Extract Parameter Object: Many parameters → single object
Output Format
# Refactoring Results
## Target
- File: {file_path}
- Refactor Type: {type}
## Changes Applied
### {Refactoring Name}
- Location: `file.cs:line`
- Before:
```csharp
// old code
- After:
// refactored code
- Benefit: {explanation}
Summary
- Total refactorings: {N}
- Lines changed: {N}
- New files created: {list if any}
Recommendations
- Further improvements that could be made
- Related patterns to consider
## Guidelines
- Preserve existing functionality (no behavior changes)
- Make incremental changes, not massive rewrites
- Prioritize readability over cleverness
- Consider team familiarity with patterns
- Add comments only where logic is non-obvious
- Run tests after each refactoring if available