AterraEngine.Unions.Generators 0.5.0-alpha

🔗 AterraEngine.Unions 🔗

A Union Library for DotNet

Overview

AterraEngine.Unions is a comprehensive library for creating and managing union types in .NET. It leverages the latest features of C# 13.0 and .NET 9.0 to provide a robust and efficient framework for representing multiple and diverse data types as a single unit. The package was inspired by the OneOf package.

Features

• Type Safety: Ensure type safety with union types that encapsulate various data forms.
• Ease of Use: Simplified API to integrate union types seamlessly into your project.
• Performance Optimizations: Designed with performance in mind to handle high-scale applications.
• Generate: Not satisfied with the basic unions we have made for you? No worries, you can generate your own using AterraEngine.Unions.Generator
• Auto Alias: Instead of having a pre-made Union<T0,T1,...> base type which simply provides a IsT0 or AsT1 api, this package generates all unions from the ground up.
  • This allows us to create insert any names we want. By default, it will choose the name of the types chosen for the aliases, example : IsTrue AsString.
  • You can also set your own alias for specific types using the attribute [UnionAliases(aliasT2:"Something")]. See usage in the example below.
• Up to 16: By default the IUnion<> interface allows up to 16 types within the union. Because we use casting instead of the index based approach by OneOf, there doesn't need to be a limit to this in the future.

Getting Started

Installation

You can install AterraEngine.Unions via NuGet Package Manager:

dotnet add package AterraEngine.Unions

You can install AterraEngine.Unions.Generator via NuGet Package Manager:

dotnet add package AterraEngine.Unions.Generator

Usage

Here is a basic example to demonstrate how to create and use union types with AterraEngine.Unions.

using AterraEngine.Unions;

TrueOrFalse trueOrFalse = new True();

if (trueOrFalse.IsTrue) {    
    // Do stuff here
}

using AterraEngine.Unions;

ManyOneNoneOrError<int, string> union = new Many<int>([1, 2, 3]);
if (union.TryGetAsMany(out Many<T> values) {
  // Do stuff here
}
if (union.TryGetAsOne(out One<T> value) {
  // Do stuff here
}
if (union.TryGetAsNone(out None value) {
  // Do stuff here
}
if (union.TryGetAsError(out Error<T> value) {
  // Do stuff here
}

Using .Value will incur boxing. If you want to avoid boxing, it is currently advised to use the TryGetAs{TypeName} method or a combination of Is{TypeName} and As{Typename} properties.

using AterraEngine.Unions;

ManyOneNoneOrError<int, string> union = new One<int>(1);
switch (union.Value) {
    case Many<int>: //...
    case One<int>: //...
    case None: //...
    case Error: //...
}

if (union.TryGetAsNone(out None value) {
    // ...        
}

Another version of using the switch case would be like the following example. Although a little more cumbersome to write, it will do the same as the above example, without boxing.

TrueOrFalse union = new False();
switch (union) {
    case {IsTrue: true, AsTrue: var trueValue}: 
        Assert.Equal(new True(), trueValue);
        break;
    case {IsFalse: true, AsFalse: var falseValue}: 
        Assert.Equal(new False(), falseValue);
        break;
}

Creating your own unions is easily done by installing AterraEngine.Unions.Generators and following the example:

using AterraEngine.Unions;

[UnionAliases(aliasT2:"ErrorTuple")]
public readonly partial struct TrueFalseOrErrorTuple() : IUnion<True, False, (Error<string>, Type)>;
// Which will generate the following, instead of a default generated name for the 3rd type in the union.
// - IsErrorTuple
// - AsErrorTuple
// - TryGetErrorTuple(...)

Here is an advanced example demonstrating a custom union type with user-defined aliases:

using AterraEngine.Unions;

[UnionAliases(aliasT2: "ErrorTuple")]
public readonly partial struct TrueFalseOrErrorTuple : IUnion<True, False, (Error<string>, Type)>;

class Program {
    static void Main() {
        TrueFalseOrErrorTuple union = new True();
        
        if (union.IsTrue) {
            Console.WriteLine("It's true!");
        }

        // Using the custom alias
        union = new ((new Error<string>("An error occurred"), typeof(int)));

        if (union.IsErrorTuple) {
            var errorTuple = union.AsErrorTuple;
            Console.WriteLine($"Error: {errorTuple.Item1.Message}, Type: {errorTuple.Item2}");
        }
    }
}

Benchmarks

The following is a result of the benchmarks found at Benchmarks.AterraEngine.Unions.