Praefixum - Unique ID Generator for .NET

Praefixum is a .NET 10 source generator that emits interceptors for automatic unique ID generation. It enables deterministic, human-friendly identifiers to be generated for method parameters marked with the [UniqueId] attribute.

🚀 Features

• Build-time interceptors - Generated code handles IDs without manual wiring
• Deterministic by call site - Same code location generates stable IDs
• Multiple parameter support - Handle multiple [UniqueId] parameters in a single method
• Multiple formats - Support for HTML IDs, GUIDs, timestamps, and hash-based IDs
• Prefix support - Add custom prefixes to generated IDs
• Interceptor-based - Uses .NET 10 preview interceptors for seamless integration
• Thread-safe - Generated IDs are constants, no concurrency issues
• Zero dependencies - Pure source generator implementation

📦 Installation

Install via NuGet Package Manager:

dotnet add package Praefixum

Or via Package Manager Console:

Install-Package Praefixum

🎯 Quick Start

1. Define a method with UniqueId parameter

using Praefixum; public static string CreateButton( string text, [UniqueId(UniqueIdFormat.HtmlId)] string? id = null) { return $"<button id=\"{id}\">{text}</button>"; }

2. Use the method

// Each call generates a unique ID via the generated interceptor var button1 = CreateButton("Click me"); // <button id="a1b2c3d4">Click me</button> var button2 = CreateButton("Submit"); // <button id="x9y8z1w2">Submit</button>

3. Compilation magic ✨

The source generator emits interceptors that replace null [UniqueId] parameters with generated IDs based on the call location.

🎨 Supported ID Formats

Format	Example	Description
HtmlId	a1b2c3d4	HTML5-compliant ID (starts with letter, 8 characters)
Guid	a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6	32-character deterministic GUID (no dashes)
Timestamp	1735052327842	Unix timestamp in milliseconds
ShortHash	YWJjZGVm	8-character Base64-encoded hash

📖 Usage Examples

HTML ID Generation

public static string Div( string content, [UniqueId(UniqueIdFormat.HtmlId, prefix: "div-")] string? id = null) { return $"<div id=\"{id}\">{content}</div>"; } // Usage var html = Div("Hello World"); // <div id="div-a1b2c3d4">Hello World</div>

Multiple Parameters

NEW: Praefixum now supports multiple [UniqueId] parameters in a single method!

public static string Form( [UniqueId(UniqueIdFormat.HtmlId, prefix: "form-")] string? formId = null, [UniqueId(UniqueIdFormat.HtmlId)] string? nameInputId = null, [UniqueId(UniqueIdFormat.HtmlId)] string? emailInputId = null, [UniqueId(UniqueIdFormat.Guid)] string? submitId = null) { return $@" <form id=""{formId}""> <input id=""{nameInputId}"" name=""name"" type=""text"" /> <input id=""{emailInputId}"" name=""email"" type=""email"" /> <button id=""{submitId}"" type=""submit"">Submit</button> </form>"; } // Usage - all IDs are automatically generated and unique var form = Form(); // Generates: form-x1y2z3w4, a5b6c7d8, e9f0g1h2, i3j4k5l6m7n8o9p0q1r2s3t4u5v6w7x8

Custom Prefixes

public static string Input( [UniqueId(UniqueIdFormat.HtmlId, prefix: "input-")] string? id = null) { return $"<input id=\"{id}\" type=\"text\" />"; }

Different Formats in Same Method

public static string Widget( [UniqueId(UniqueIdFormat.HtmlId)] string? elementId = null, [UniqueId(UniqueIdFormat.Timestamp)] string? timestampId = null, [UniqueId(UniqueIdFormat.Guid)] string? uuid = null) { return $@" <div id=""{elementId}"" data-timestamp=""{timestampId}"" data-uuid=""{uuid}""> Widget Content </div>"; }

🏗️ How It Works

1. Attribute Detection: The source generator scans for methods with [UniqueId] parameters
2. Call Site Analysis: Identifies calls to methods with [UniqueId] parameters
3. Interceptor Generation: Creates interceptor methods for each call site using .NET 10 preview interceptors
4. ID Generation: Generates IDs from call-site location data at build time
5. Invocation: The interceptor fills null parameters with literal IDs and calls the original method

Generated Code Example

For this source code:

var form = CreateFormWithMultipleIds(); // Line 42, Column 12

The generator creates an interceptor that:

1. Checks if all [UniqueId] parameters are provided
2. If any are null, generates unique IDs based on call site + parameter index
3. Calls the original method with generated or provided IDs

[InterceptsLocation(1, "D:\\MyProject\\Program.cs(42,12)")] public static string CreateFormWithMultipleIds_0( string? formId = null, string? nameInputId = null, string? emailInputId = null, string? submitButtonId = null) { // Check if all parameters provided if (formId != null && nameInputId != null && emailInputId != null && submitButtonId != null) return OriginalClass.CreateFormWithMultipleIds(formId, nameInputId, emailInputId, submitButtonId); // Generate IDs for null parameters var formIdFinal = formId ?? GenerateId("key:0", 1, UniqueIdFormat.HtmlId, "form-"); var nameInputIdFinal = nameInputId ?? GenerateId("key:1", 1, UniqueIdFormat.HtmlId, null); var emailInputIdFinal = emailInputId ?? GenerateId("key:2", 1, UniqueIdFormat.HtmlId, null); var submitButtonIdFinal = submitButtonId ?? GenerateId("key:3", 1, UniqueIdFormat.Guid, null); return OriginalClass.CreateFormWithMultipleIds(formIdFinal, nameInputIdFinal, emailInputIdFinal, submitButtonIdFinal); }

🧪 Testing

The project includes a comprehensive test suite covering:

• Basic functionality - Core ID generation and validation
• Multiple parameter support - Methods with multiple [UniqueId] parameters
• Format compliance - Each format meets its specification
• Edge cases - Error conditions and unusual scenarios
• Performance - Concurrency and load testing
• Integration - Real-world usage patterns with actual [UniqueId] attributes

Run tests with:

dotnet test

🔧 Requirements

• .NET 10.0 or later (for interceptor support)
• C# preview (interceptors are preview)
• EnablePreviewFeatures and InterceptorsNamespaces enabled in your project

<PropertyGroup> <TargetFramework>net10.0</TargetFramework> <LangVersion>preview</LangVersion> <EnablePreviewFeatures>true</EnablePreviewFeatures> <InterceptorsNamespaces>$(InterceptorsNamespaces);Praefixum</InterceptorsNamespaces> </PropertyGroup>

🤝 Contributing

We welcome contributions! Please see CONTRIBUTING.md for guidelines.

Development Setup

1. Clone the repository
2. Run dotnet restore
3. Run dotnet build to build all projects
4. Run dotnet test to execute the test suite

📋 Project Structure

Praefixum/ ├── Praefixum/ # Main source generator project │ ├── UniqueIdGenerator.cs # Core source generator logic │ └── UniqueIdAttribute.cs # Attribute definitions ├── Praefixum.Demo/ # Demo application │ ├── Program.cs # Console demo │ └── Html.cs # HTML generation examples ├── Praefixum.Tests/ # Comprehensive test suite │ ├── UniqueIdGeneratorBasicTests.cs │ ├── UniqueIdGeneratorEdgeCaseTests.cs │ ├── UniqueIdFormatTests.cs │ ├── UniqueIdGeneratorPerformanceTests.cs │ └── TestHelpers.cs └── docs/ # Documentation

📈 Performance

• No runtime ID generation - IDs are compile-time literals in generated code
• Fast compilation - Minimal impact on build time
• Memory efficient - No runtime allocations for ID generation
• Thread-safe - Generated constants are inherently thread-safe

🐛 Troubleshooting

Common Issues

Q: IDs are not being generated A: Ensure you're using .NET 10 and have enabled preview features and interceptors in your project.

Q: Duplicate ID errors A: This indicates the same call site is generating multiple IDs. Check your code structure.

Q: Build errors with interceptors A: Verify your project targets .NET 10, LangVersion is preview, and preview features are enabled.

📄 License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.

🙏 Acknowledgments

• Built with Roslyn source generators
• Uses .NET 10 preview interceptor feature
• Inspired by compile-time code generation patterns

Made with ❤️ for the .NET community