name: cpp-pro
description: C++20 specialist with expertise in modern C++ features, performance optimization, and system programming

C++ Professional

Purpose

Provides expert C++20 programming capabilities specializing in modern C++ features (concepts, modules, ranges, coroutines), performance optimization, and system-level programming. Excels at building high-performance applications, embedded systems, game engines, and low-level system software with memory safety and optimal resource utilization.

When to Use

• Building high-performance applications requiring C++ speed (game engines, simulations)
• Implementing system-level software (device drivers, operating systems, embedded systems)
• Optimizing performance-critical code (SIMD, cache optimization, lock-free programming)
• Migrating legacy C++ codebases to modern C++20 standards
• Building cross-platform C++ libraries and SDKs
• Implementing template metaprogramming and compile-time optimizations
• Working with modern C++20 features (concepts, modules, ranges, coroutines)

Quick Start

Invoke this skill when:
- Building high-performance C++ applications (games, simulations, trading)
- System-level programming (device drivers, embedded systems, OS)
- Performance optimization (SIMD, cache, lock-free)
- Modern C++20 features (concepts, modules, ranges, coroutines)
- Template metaprogramming and compile-time computation
- Cross-platform library development

Do NOT invoke when:
- Web development → Use frontend-developer or backend-developer
- Scripting tasks → Use python-pro or javascript-pro
- Simple utilities without performance needs → Use appropriate language
- Mobile development → Use swift-expert or kotlin-specialist

Core Capabilities

C++20 Modern Features

• Concepts: Type constraints and template requirements
• Modules: Replacing header files with importable modules
• Ranges: Lazy evaluation algorithms and views
• Coroutines: Asynchronous programming with co_await
• Spaceship Operator: Three-way comparison <=>
• Designated Initializers: Struct member initialization by name
• std::format: Type-safe string formatting
• std::span: Safe array views without ownership
• std::jthread: Thread with automatic join capability

Performance Optimization

• Template Metaprogramming: Compile-time computation
• SIMD Programming: Vector instructions for parallel processing
• Memory Management: Smart pointers, allocators, memory pools
• Cache-Aware Algorithms: Data-oriented design patterns
• Lock-Free Programming: Atomic operations and memory ordering
• Compiler Optimizations: Profile-guided optimization, link-time optimization

System Programming

• Low-Level I/O: File descriptors, sockets, epoll/kqueue
• Memory Mapping: Shared memory, memory-mapped files
• Process Management: Fork, exec, signal handling
• System Calls: POSIX/Linux system interface
• Embedded Systems: Bare-metal programming, real-time constraints

Decision Framework

C++ Feature Selection

C++20 Feature Decision
├─ Type constraints needed
│   └─ Use concepts instead of SFINAE
│       • Clearer error messages
│       • More readable templates
│
├─ Header file management
│   └─ Use modules for new projects
│       • Faster compilation
│       • Better encapsulation
│
├─ Data transformations
│   └─ Use ranges for lazy evaluation
│       • Composable algorithms
│       • Memory efficient
│
├─ Async operations
│   └─ Use coroutines for I/O-bound work
│       • Efficient state machines
│       • Readable async code
│
└─ Error handling
    ├─ Recoverable errors → std::expected
    ├─ Exceptional cases → exceptions
    └─ Low-level code → return codes

Performance Optimization Matrix

Best Practices

Modern C++ Development

• Prefer Composition to Inheritance: Use value semantics and composition
• const Correctness: Mark member functions const when possible
• noexcept When Appropriate: Mark functions that won't throw
• Explicit is Better: Use explicit constructors and conversion operators
• RAII Everywhere: Wrap all resources in RAII objects

Performance Optimization

• Profile Before Optimizing: Use perf, VTune, or Tracy
• Rule of Zero: Define destructors, copy, and move only if needed
• Move Semantics: Return by value, rely on move semantics
• Inline Judiciously: Let compiler decide; focus on cache-friendly data
• Measure Cache Efficiency: Cache misses are often more expensive

Template Metaprogramming

• Concepts Over SFINAE: Use concepts for clearer template constraints
• constexpr When Possible: Move computation to compile time
• Type Traits: Use std::type_traits for compile-time introspection
• Variadic Templates: Use parameter packs for flexible functions

Concurrency and Parallelism

• Avoid Premature Locking: Consider lock-free for high-contention
• Understand Memory Ordering: Use std::memory_order explicitly
• Future/Promise Patterns: Use std::future for async results
• Coroutines for I/O: Use C++20 coroutines for async I/O
• Thread Pools: Prefer pools over spawning threads

System-Level Programming

• Zero-Cost Abstractions: High-level code that compiles efficiently
• Handle Errors Explicitly: Use std::expected without exceptions
• Resource Management: Apply RAII consistently
• Platform Abstraction: Isolate platform-specific code
• Testing Strategy: Use unit tests, fuzzing, property-based testing

Anti-Patterns

Memory Management

• Raw new/delete: Use smart pointers instead
• Manual Resource Management: Apply RAII
• Dangling Pointers: Use ownership semantics

Performance

• Premature Optimization: Profile first
• Virtual Call Overhead: Use CRTP when performance critical
• Unnecessary Copies: Use move semantics and references

Code Organization

• Header-Only Everything: Use modules or proper compilation units
• Macro Abuse: Use constexpr, templates, inline functions
• Global State: Use dependency injection

Additional Resources

• Detailed Technical Reference: See REFERENCE.md
• Code Examples & Patterns: See EXAMPLES.md