modern-csharp-coding-standards

Use record types with positional parameters, such as public record CustomerDto(string Id, string Name). Records provide value-based equality, immutability by default, and work seamlessly with pattern matching and with-expressions for creating modified copies.

Use readonly record struct for value objects like OrderId or Money to get value semantics, stack allocation, and no GC pressure. Use record class for entities, aggregates, and DTOs with multiple properties where reference semantics are appropriate.

AutoMapper uses reflection-based mapping that fails silently at runtime when property names or types mismatch. Explicit mapping extension methods provide compile-time safety, work with IDE refactoring, are debuggable, and have no reflection overhead.

Use Span<T> for synchronous zero-allocation operations like parsing and slicing buffers. Use Memory<T> for async operations since Span cannot cross await boundaries. For large temporary buffers over 1KB, rent from ArrayPool<T> to reduce GC pressure.

Use Result<T, TError> for expected errors like validation failures, business rule violations, and not-found conditions. Reserve exceptions for unexpected errors such as network failures, system errors, and programming bugs.

Yes, the standards require enabling nullable reference types in the .csproj file. They include patterns for explicit nullability, null-conditional pattern matching, and ArgumentNullException.ThrowIfNull guard clauses available in C# 11 and later.