neo-csharp

跨版本 C# 專家技能 (10, 11, 12, 13, 14+)。支援從 .NET 6 (LTS) 到 .NET 10 (LTS) 的現代開發模式，涵蓋 File-scoped namespaces 到 Extension Types 的全方位演進。

Modern C# (10+) Expert Skill

Trigger On

  • The user asks to write, debug, refactor, or review C# code.
  • The project directory contains *.cs, *.csproj, or single-file C# scripts.
  • The target framework is .NET 6.0 (LTS) and above.
  • Code modernization is needed (e.g., converting legacy nested namespaces to File-scoped namespaces).

Workflow

  1. Perceive (Version Awareness):
    • Check .csproj to identify TargetFramework and determine the syntax upper limit:
      • net6.0: C# 10 (File-scoped namespaces, Global usings).
      • net7.0: C# 11 (Raw string literals, Required members).
      • net8.0: C# 12 (Primary Constructors, Collection Expressions).
      • net9.0: C# 13 (params collections, Lock object).
      • net10.0: C# 14 (Extension members, field keyword).
  2. Reason (Planning Phase):
    • Evaluate the modernization level of the current code to determine the refactoring strategy.
    • In lower version environments (like .NET 6), avoid using higher version syntax (like Primary Constructors), but prioritize using File-scoped namespaces.
    • In higher version environments, actively adopt new features to reduce boilerplate code.
  3. Act (Execution Phase):
    • Write high-quality code, prioritizing "syntactic sugar" to improve readability.
    • Implement strong typing and immutable data structures (record, record struct).
    • Utilize Interpolated string handlers and Span<T> to optimize performance-sensitive paths.
  4. Validate (Standard Validation):
    • Validate the safety of NRT (Nullable Reference Types).
    • Check if asynchronous operations correctly handle cancellation tokens (CancellationToken).
    • Ensure naming conventions comply with official .NET recommendations.

Feature Roadmap (C# 10 - 14)

C# 10 & 11 (Foundation)

  • File-scoped Namespaces: Reduce indentation levels.
  • Global Using Directives: Centralize common namespaces management.
  • Raw String Literals: """...""" easily handle multi-line and special characters.
  • Required Members: Ensure required properties during object initialization.
  • List Patterns: if (list is [1, 2, ..]) powerful collection matching.

C# 12 & 13 (Productivity)

  • Primary Constructors: Simplify class-level dependency injection.
  • Collection Expressions: Uniformly use [1, 2, 3] to initialize collections.
  • params Collections: Method parameters support various collection types.
  • Implicit Span Conversion: Handle memory-safe code more naturally.

C# 14+ (Cutting Edge)

  • Extension Members: Extension properties, operators, and static members.
  • field Keyword: Directly access backing fields in property logic.
  • Null-conditional Assignment: target?.Property = value;.
  • Scripting: Support dotnet run file.cs for direct execution.

Coding Standards

  • Clean Structure: Prioritize using File-scoped namespaces.
  • Immutability: Use record for Data Transfer Objects (DTO).
  • Performance: Use Span<T> and ReadOnlySpan<char> in critical paths.
  • Async Safety: Always pass CancellationToken, avoid .Result or .Wait().

Deliver

  • Version-Optimized Code: Provide the most appropriate modernized syntax code based on the target C# version.
  • Modernization Insights: Provide specific refactoring suggestions for upgrading from older C# syntax to new features (e.g., from nested namespaces to File-scoped namespaces).
  • Syntax Explanations: Clearly explain the design intent and syntax advantages behind the new C# features used.

Validate

  • Ensure the provided code complies with the syntax specifications of the target C# version.
  • Validate whether the code follows C# strong typing and Null safety (NRT) principles.
  • Confirm the code has good readability and best practices at the pure C# language level (e.g., proper use of Span<T>, record, etc.).

Documentation

Official References

Internal References