What is the 'polyfill-first' approach in .NET?

It is a strategy that prioritizes using source generators like PolySharp to provide compiler stubs for modern features on older frameworks, reducing the need for messy #if conditional compilation blocks.

Does using PolySharp add runtime dependencies?

No, PolySharp is a source generator that works entirely at compile time. It adds no runtime overhead and only generates code for features missing in the target TFM.

When should I use #if conditional compilation instead of polyfills?

Use conditional compilation when dealing with runtime behavior differences, platform-specific APIs (like Windows Registry), or when using TFM-specific hardware-accelerated APIs.

How does this skill interact with .NET version detection?

This skill consumes structured output from the dotnet-version-detection skill to understand the specific TFM and C# version context before recommending compatibility strategies.

.NET Multi-Targeting Expert

Name: .NET Multi-Targeting Expert
Author: rudironsoni

byrudironsoni

0•

Developer Tools

Streamlines development across multiple .NET Target Frameworks using polyfill-first strategies and conditional compilation patterns.

The dotnet-multi-targeting skill provides Claude with advanced architectural guidance for managing C# projects that must support multiple .NET versions (TFMs). It prioritizes modern development practices by leveraging PolySharp for compiler-synthesized polyfills and SimonCropp/Polyfill for BCL API backporting, allowing developers to use modern C# features on older runtimes. By following a structured decision matrix, the skill helps determine when to use polyfills versus conditional compilation, ensuring codebases remain clean, maintainable, and performant across the entire .NET ecosystem.

Key Features

01Standardized patterns for TFM-based preprocessor symbols

02Decision matrix for polyfill vs. conditional compilation strategies

03PolySharp integration for modern C# syntax support on older TFMs

04BCL API backporting guidance using SimonCropp/Polyfill

05Best practices for multi-targeting .csproj configurations

060 GitHub stars

Use Cases

01Backporting modern C# language features like 'required' members and 'init' properties to legacy projects

02Implementing TFM-specific performance optimizations using APIs like SearchValues or FrozenDictionary

03Developing NuGet libraries that require support for .NET Standard 2.0 alongside modern .NET 8/9+

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add rudironsoni/rulesync-dotnet dotnet-multi-targeting

For use in Claude.ai and ChatGPT

Key Features

01Standardized patterns for TFM-based preprocessor symbols

02Decision matrix for polyfill vs. conditional compilation strategies

03PolySharp integration for modern C# syntax support on older TFMs

04BCL API backporting guidance using SimonCropp/Polyfill

05Best practices for multi-targeting .csproj configurations

060 GitHub stars

Use Cases

01Backporting modern C# language features like 'required' members and 'init' properties to legacy projects

02Implementing TFM-specific performance optimizations using APIs like SearchValues or FrozenDictionary

03Developing NuGet libraries that require support for .NET Standard 2.0 alongside modern .NET 8/9+

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add rudironsoni/rulesync-dotnet dotnet-multi-targeting

For use in Claude.ai and ChatGPT