README.md

🎭 Emulating Associated Value Enums in C#

This repository provides an example of how to emulate Swift's Associated Value Enums in C#. It demonstrates how to create a C# interface that acts like an enum type, and uses default interface methods to provide struct implementations that store associated values. 🧠💡

📚 Example from Swift Documentation

Let's take an example from the Swift documentation:

enum Barcode {
    case upc(Int, Int, Int, Int)
    case qrCode(String)
}

The Barcode enum has two cases, upc and qrCode. The upc case has four associated values of type Int, and the qrCode case has one associated value of type String. 🏷️

🖥️ C# Implementation

The best way to emulate this in C# is to create an interface IBarcode that acts like the Barcode enum type. Each value of the enum has a default interface method and a struct that stores the associated value. 🛠️

public interface IBarcode {
    public UPC Upc(int numberSystem, int manufacturer, int product, int check)
    {
        return new UPC { NumberSystem = numberSystem, Manufacturer = manufacturer, Product = product, Check = check };
    }

   public QRCode QrCode(string productCode)
    {
        return new QRCode { ProductCode = productCode };
    }
}

In this example, UPC and QRCode are two structs that implement the IBarcode interface. UPC has four properties that correspond to the associated values of the upc case in the Swift example, and QRCode has one property that corresponds to the associated value of the qrCode case. 🏗️

public struct UPC : IBarcode
{
    public int NumberSystem { get; set; }
    public int Manufacturer { get; set; }
    public int Product { get; set; }
    public int Check { get; set; }
}

public struct QRCode : IBarcode
{
    public string ProductCode { get; set; }
}

🚀 Using the Emulated Enum in C#

To use the emulated enum in C#, you can create an instance of the IBarcode interface with the associated values of the struct. For example, to create a Barcode.upc instance with values 8, 85909, 51226, and 3, you would do the following:

IBarcode barcode = new UPC { NumberSystem = 8, Manufacturer = 85909, Product = 51226, Check = 3 };

To create a Barcode.qrCode instance with value "ABCDEFGHIJKLMNOP", you would do the following:

IBarcode barcode = new QRCode { ProductCode = "ABCDEFGHIJKLMNOP" }; 

You can use the emulated enum in a switch statement to perform different actions depending on the type of the associated value. For example, to print the associated values of a Barcode.upc instance or Barcode.qrCode instance, you can use the following code:

switch (barcode)
{
    case UPC upc:
        Console.WriteLine($"UPC: {upc.NumberSystem}, {upc.Manufacturer}, {upc.Product}, {upc.Check}.");
        break;
    case QRCode qrCode:
        Console.WriteLine($"QR code: {qrCode.ProductCode}.");
        break;
} 

📜 License

This code is licensed under the MIT License.

📚 References

• Swift Documentation: Enumerations - Associated Values
• Microsoft C# 8.0 - Default Interface Methods