Proxy: Next Generation Polymorphism

Modern C++ demands a rethinking of polymorphism that moves beyond the constraints of classical inheritance while preserving performance and safety. In this talk, I will introduce Proxy — an open-source header-only C++20 library for non-intrusive polymorphism designed and refined by Microsoft. Proxy leverages pointer-based lifetime management to offer a GC-like capability without incurring the overhead of a garbage collector. Please find more information from our GitHub repository: https://github.com/microsoft/proxy. The library’s design is a response to long-standing challenges in traditional polymorphic code. It provides an alternative to inheritance by allowing any expression, be it member functions, free functions, operators, or conversions, to participate in a unified abstraction. Developed with portability, efficiency, and ease-of-use in mind, Proxy is engineered as a freestanding solution that works consistently across platforms—from embedded systems to operating systems, where it has been deployed in production since 2022. Key points of discussion will include: Non-Intrusive Abstraction: How Proxy eliminates the need for inheritance, making polymorphic interfaces simpler yet powerful; Lifetime Management: The innovative approach to managing object lifetimes, which offers performance competitive with hand-crafted solutions while avoiding common pitfalls; Flexibility and Performance: Detailed considerations on balancing API accessibility and efficient resource handling in a modern C++ ecosystem; Real-World Impact: Lessons learned from using Proxy in a large-scale, production environment, and a comparison with alternative polymorphic programming techniques. Join me for an in-depth exploration of Proxy’s design decisions, practical applications, and potential future directions that reimagine polymorphism for the next generation of C++ development. Please find more information from our GitHub repository: https://github.com/microsoft/proxy Microsoft for C++ developers: https://developer.microsoft.com/en-us/cpp