# microsoft/proxy

Proxy: Next Generation Polymorphism in C++

Repository: https://github.com/microsoft/proxy
Canonical: https://ross.abutalabs.com/products/proxy
Homepage: https://microsoft.github.io/proxy/spec/
Language: C++
License: MIT
License Family: permissive
Topics: cpp, cpp20, header-only, library, cross-platform, polymorphism, duck-typing, single-header
Archived: true
Last push: 2026-01-29T09:21:48+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 64, release rhythm 38, longevity 100
- inputs: {"age_days": 1556, "days_push": 216, "days_rel": 332, "gap_med": 58, "n_releases_24m": 8}
- flags: archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3040, forks 223 (observed 2026-08-28T04:07:39.251479+00:00)

## What it is
Proxy is a header-only C++20 library from Microsoft that provides next-generation polymorphism without inheritance, using pointer-based facades and compile-time facade builders. It is portable, non-intrusive, and freestanding, suitable even for embedded or kernel-level code.

## Use cases
- replace inheritance-based polymorphism in C++ with a faster alternative
- write polymorphic code in C++ as easily as in Java or C#
- type-erase arbitrary types without intrusive base classes
- use polymorphism in freestanding or embedded environments
- manage lifetimes of polymorphic objects safely
- build traits-like abstractions similar to Rust in C++

## When to choose
- you need polymorphism without inheritance or intrusive modifications to types
- you target C++20 and want a portable, header-only solution
- performance matters and you want to avoid virtual-call overhead and heap allocation where possible
- you work in freestanding environments like kernels or embedded systems

## When to avoid
- your codebase must compile with pre-C++20 compilers
- you prefer classic OOP inheritance hierarchies and virtual functions
- you need a maintained upstream - this Microsoft repo is archived; use ngcpp/proxy instead

## Facets
- artifact type: library
- maturity: maintenance
- function: programming-language, developer-tools
- domain: programming-languages, developer-tools, cross-platform
- platform: cpp, cross-platform, windows
- tags: cpp20, header-only, polymorphism, duck-typing, single-header, type-erasure, no-inheritance, linux, macos

## Member repositories
- microsoft/proxy (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:39.251479+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:46:50.968165+00:00, confidence not recorded.
  - readme: https://github.com/microsoft/proxy (fetched 2026-08-28T04:07:39.251479+00:00, sha a2cdafdcd368)
  - homepage: https://microsoft.github.io/proxy/spec/ (fetched 2026-08-29T09:44:19.452996+00:00, sha 59e4846f833e)
- Data as of 2026-08-30T08:39:29.467469+00:00.