awesome-claude-copilot csharp.instructions.md

C# Development

Instructions

• Always use the latest version C#, currently C# 14 features.
• Make only high confidence suggestions when reviewing code changes.
• Write maintainable code; handle edge cases with clear exception handling.
• Comment only what code cannot say: why-decisions, constraints, non-obvious invariants. Never restate what the code does or narrate a change.
• Web/API-specific standards (auth, validation, versioning, performance, deployment) live in aspnet-rest-apis.instructions.md.

Naming Conventions

• Follow PascalCase for component names, method names, and public members.
• Prefix private fields with an underscore and use _camelCase (e.g., _userService, _cache).
• Use camelCase for local variables and parameters.
• Prefix interface names with "I" (e.g., IUserService).

Modern C# Constructs

• Prefer primary constructors for classes (services, controllers, handlers). Capture every injected dependency into a private readonly _camelCase field at the top of the class, and reference the field — not the primary-constructor parameter — in method bodies:

  public class UserService(IUserRepository repository, ILogger<UserService> logger) : IUserService
  {
      private readonly IUserRepository _repository = repository;
      private readonly ILogger<UserService> _logger = logger;
  }
  

• Prefer collection expressions wherever the target type is clear: [] for empty collections, [1, 2, 3] for literals, and spreads like [.. items, extra]. Do not write new List<T>(), new T[] { }, or Array.Empty<T>() when a collection expression works:

  private readonly List<string> _names = [];
  string[] merged = [.. first, .. second];
  

Formatting

• Apply code-formatting style defined in .editorconfig.
• Prefer file-scoped namespace declarations and single-line using directives.
• Insert a newline before the opening curly brace of any code block (e.g., after if, for, while, foreach, using, try, etc.).
• Ensure that the final return statement of a method is on its own line.
• Use pattern matching and switch expressions wherever possible.
• Use nameof instead of string literals when referring to member names.
• Ensure that XML doc comments are created for any public APIs. When applicable, include <example> and <code> documentation in the comments.