csharp-advanced-patterns

Async/await in C# enables non-blocking asynchronous operations by allowing methods to pause execution and resume when tasks complete. Use async methods with await keywords for I/O-bound operations, pair them with ValueTask for high-frequency scenarios, and implement CancellationToken for graceful cancellation to build responsive applications.

Span<T> and Memory<T> enable allocation-free data processing by providing stack-allocated or heap-allocated views over contiguous memory. Use Span<T> for synchronous low-level operations and Memory<T> for asynchronous contexts to eliminate unnecessary array allocations and reduce garbage collection pressure in performance-critical code.

Pattern matching in C# enables expressive conditional logic across types and values, while records provide immutable data carriers with built-in equality. Combine them to validate objects concisely, implement discriminated unions, and create robust data models that reduce boilerplate and improve code maintainability.

ValueTask reduces heap allocations for operations that complete synchronously or very frequently by returning a value type instead of an object reference. Use ValueTask in high-throughput async methods where the operation often completes before awaiting to avoid unnecessary allocations and improve performance.

Modern C# offers primary constructors, collection expressions, and pattern matching to simplify existing code. Incrementally replace conventional constructors with primary constructors, convert LINQ queries to collection expressions, and apply pattern matching to reduce conditional nesting for clearer, more maintainable legacy refactoring.

Dependency Injection decouples components and enables testability; Strategy pattern encapsulates interchangeable algorithms; Decorator pattern adds behavior dynamically. Apply these patterns with modern C# records and pattern matching to create flexible architectures that adapt to changing requirements without modifying existing code.