modern-csharp-coding-standards

1# Modern C# Coding Standards
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3## When to Use This Skill
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5Use this skill when:
6- Writing new C# code or refactoring existing code
7- Designing public APIs for libraries or services
8- Optimizing performance-critical code paths
9- Implementing domain models with strong typing
10- Building async/await-heavy applications
11- Working with binary data, buffers, or high-throughput scenarios
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13## Reference Files
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15- [value-objects-and-patterns.md](value-objects-and-patterns.md): Full value object examples and pattern matching code
16- [performance-and-api-design.md](performance-and-api-design.md): Span<T>/Memory<T> examples and API design principles
17- [composition-and-error-handling.md](composition-and-error-handling.md): Composition over inheritance, Result type, testing patterns
18- [anti-patterns-and-reflection.md](anti-patterns-and-reflection.md): Reflection avoidance and common anti-patterns
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20## Core Principles
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221. **Immutability by Default** - Use `record` types and `init`-only properties
232. **Type Safety** - Leverage nullable reference types and value objects
243. **Modern Pattern Matching** - Use `switch` expressions and patterns extensively
254. **Async Everywhere** - Prefer async APIs with proper cancellation support
265. **Zero-Allocation Patterns** - Use `Span<T>` and `Memory<T>` for performance-critical code
276. **API Design** - Accept abstractions, return appropriately specific types
287. **Composition Over Inheritance** - Avoid abstract base classes, prefer composition
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