.NET AYUDA

C# Unión Discriminada (Cómo Funciona para Desarrolladores)

Actualizado:julio 28, 2025

Discriminated Unions, also known as tagged unions or sum types, represent a powerful tool to model data that can take different forms, but with well-defined and limited possible cases. Although C# doesn't have native discriminated unions like some other languages (e.g., F# or Rust), you can simulate discriminated unions using several techniques in the language. In this tutorial, we'll dive into discriminated unions, how to implement them in C#, and their practical use case with the IronPDF library.

What is a Discriminated Union?

In simple terms, a discriminated union is a type that can hold one of several predefined forms or values. It provides a way to create a type-safe structure that encapsulates different types or values while ensuring at compile time that only valid cases are handled.

Imagine a scenario where you want to represent the result of an operation. The operation can either succeed, returning some data, or fail, returning an error message. A discriminated union would allow you to represent these two possible outcomes in a single type.

Example: Simulating Discriminated Union in C#

Here’s an example of how you can simulate a discriminated union in C# using a class structure:

// Define an abstract base class representing the operation result.
public abstract class OperationResult<T>
{
    // Private constructor to ensure the class cannot be instantiated directly.
    private OperationResult() { }

    // Nested class representing a successful operation result.
    public sealed class Success : OperationResult<T>
    {
        public T Value { get; }

        public Success(T value) => Value = value;

        public override string ToString() => $"Success: {Value}";
    }

    // Nested class representing a failed operation result.
    public sealed class Failure : OperationResult<T>
    {
        public string Error { get; }

        public Failure(string error) => Error = error;

        public override string ToString() => $"Failure: {Error}";
    }

    // Factory method to create a successful operation result.
    public static OperationResult<T> CreateSuccess(T value) => new Success(value);

    // Factory method to create a failed operation result.
    public static OperationResult<T> CreateFailure(string error) => new Failure(error);
}

// Define an abstract base class representing the operation result.
public abstract class OperationResult<T>
{
    // Private constructor to ensure the class cannot be instantiated directly.
    private OperationResult() { }

    // Nested class representing a successful operation result.
    public sealed class Success : OperationResult<T>
    {
        public T Value { get; }

        public Success(T value) => Value = value;

        public override string ToString() => $"Success: {Value}";
    }

    // Nested class representing a failed operation result.
    public sealed class Failure : OperationResult<T>
    {
        public string Error { get; }

        public Failure(string error) => Error = error;

        public override string ToString() => $"Failure: {Error}";
    }

    // Factory method to create a successful operation result.
    public static OperationResult<T> CreateSuccess(T value) => new Success(value);

    // Factory method to create a failed operation result.
    public static OperationResult<T> CreateFailure(string error) => new Failure(error);
}

' Define an abstract base class representing the operation result.
Public MustInherit Class OperationResult(Of T)
	' Private constructor to ensure the class cannot be instantiated directly.
	Private Sub New()
	End Sub

	' Nested class representing a successful operation result.
	Public NotInheritable Class Success
		Inherits OperationResult(Of T)

		Public ReadOnly Property Value() As T

		Public Sub New(ByVal value As T)
			Me.Value = value
		End Sub

		Public Overrides Function ToString() As String
			Return $"Success: {Value}"
		End Function
	End Class

	' Nested class representing a failed operation result.
	Public NotInheritable Class Failure
		Inherits OperationResult(Of T)

		Public ReadOnly Property [Error]() As String

		Public Sub New(ByVal [error] As String)
			Me.Error = [error]
		End Sub

		Public Overrides Function ToString() As String
			Return $"Failure: {[Error]}"
		End Function
	End Class

	' Factory method to create a successful operation result.
	Public Shared Function CreateSuccess(ByVal value As T) As OperationResult(Of T)
		Return New Success(value)
	End Function

	' Factory method to create a failed operation result.
	Public Shared Function CreateFailure(ByVal [error] As String) As OperationResult(Of T)
		Return New Failure([error])
	End Function
End Class

$vbLabelText $csharpLabel

In this example, OperationResult<T> is an abstract class that represents our discriminated union type. It can either be a Success with a value of type T or a Failure with an error message. The private constructor ensures that instances of such a class can only be created through the predefined cases.

Using Pattern Matching with Discriminated Unions

C# provides powerful pattern-matching capabilities that work well with discriminated unions. Let’s extend our OperationResult<T> example with a method that handles different cases using a switch expression.

// Method to handle the result using pattern matching.
public string HandleResult(OperationResult<int> result) =>
    result switch
    {
        OperationResult<int>.Success success => $"Operation succeeded with value: {success.Value}",
        OperationResult<int>.Failure failure => $"Operation failed with error: {failure.Error}",
        _ => throw new InvalidOperationException("Unexpected result type")
    };

// Method to handle the result using pattern matching.
public string HandleResult(OperationResult<int> result) =>
    result switch
    {
        OperationResult<int>.Success success => $"Operation succeeded with value: {success.Value}",
        OperationResult<int>.Failure failure => $"Operation failed with error: {failure.Error}",
        _ => throw new InvalidOperationException("Unexpected result type")
    };

' Method to handle the result using pattern matching.
'INSTANT VB TODO TASK: The following 'switch expression' was not converted by Instant VB:
'public string HandleResult(OperationResult<int> result) => result switch
'	{
'		OperationResult<int>.Success success => $"Operation succeeded with value: {success.Value}",
'		OperationResult<int>.Failure failure => $"Operation failed with error: {failure.Error}",
'		_ => throw new InvalidOperationException("Unexpected result type")
'	};

$vbLabelText $csharpLabel

The switch expression here handles both the Success and Failure cases of the OperationResult<int>. This ensures that all possible cases are covered at compile time, providing type safety and reducing the risk of runtime errors.

Extension Methods for Discriminated Unions

You can extend the functionality of discriminated unions using extension methods. For example, let’s create an extension method for our OperationResult<T> to determine if the result is a success:

// Static class to hold extension methods for OperationResult<T>.
public static class OperationResultExtensions
{
    // Extension method to check if the operation result indicates success. 
    public static bool IsSuccess<T>(this OperationResult<T> result) =>
        result is OperationResult<T>.Success;
}

// Static class to hold extension methods for OperationResult<T>.
public static class OperationResultExtensions
{
    // Extension method to check if the operation result indicates success. 
    public static bool IsSuccess<T>(this OperationResult<T> result) =>
        result is OperationResult<T>.Success;
}

' Static class to hold extension methods for OperationResult<T>.
Public Module OperationResultExtensions
	' Extension method to check if the operation result indicates success. 
	<System.Runtime.CompilerServices.Extension> _
	Public Function IsSuccess(Of T)(ByVal result As OperationResult(Of T)) As Boolean
		Return TypeOf result Is OperationResult(Of T).Success
	End Function
End Module

$vbLabelText $csharpLabel

This static method checks if the result is an instance of the Success case.

Native Support for Discriminated Unions in C#

C# does not have native support for discriminated unions like some other languages, but there are ongoing discussions in the community about adding such a feature. Native discriminated unions would make it easier to define and work with union types without needing to rely on class hierarchies.

Compiler Errors and Type Safety

One of the key benefits of discriminated unions is the type safety they provide. Since all possible cases are known at compile time, the compiler can enforce that all cases are handled. This leads to fewer runtime errors and makes the code less error-prone.

For example, if you forget to handle a specific case in a switch statement, the compiler will produce an error, prompting you to address the missing case. This is especially useful when dealing with complex data structures with multiple possible cases.

Using IronPDF with Discriminated Unions in C#

C# Discriminated Union (How It Works For Developers): Figure 1 - IronPDF

IronPDF is a C# PDF library that helps developers create PDF files from HTML and allows them to modify PDF files without any hassle. When working with PDFs in C#, you can integrate IronPDF with discriminated unions to handle different scenarios when generating or processing PDF files. For example, you might have a process that either successfully generates a PDF or encounters an error. Discriminated unions allow you to model this process clearly. Let’s create a simple example where we generate a PDF using IronPDF and return the result as a discriminated union.

// Using directives for necessary namespaces.
using IronPdf;
using System;

// Define an abstract base class representing the PDF generation result.
public abstract class PdfResult
{
    // Private constructor to ensure the class cannot be instantiated directly.
    private PdfResult() { }

    // Nested class representing a successful PDF generation result.
    public sealed class Success : PdfResult
    {
        public PdfDocument Pdf { get; }

        public Success(PdfDocument pdf) => Pdf = pdf;

        public override string ToString() => "PDF generation succeeded";
    }

    // Nested class representing a failed PDF generation result.
    public sealed class Failure : PdfResult
    {
        public string ErrorMessage { get; }

        public Failure(string errorMessage) => ErrorMessage = errorMessage;

        public override string ToString() => $"PDF generation failed: {ErrorMessage}";
    }

    // Factory method to create a successful PDF result.
    public static PdfResult CreateSuccess(PdfDocument pdf) => new Success(pdf);

    // Factory method to create a failed PDF result.
    public static PdfResult CreateFailure(string errorMessage) => new Failure(errorMessage);
}

// Class to generate PDFs using IronPDF.
public class PdfGenerator
{
    // Method to generate a PDF from HTML content and return the result as a PdfResult.
    public PdfResult GeneratePdf(string htmlContent)
    {
        try
        {
            // Create a new ChromePdfRenderer instance.
            var renderer = new ChromePdfRenderer();

            // Attempt to render the HTML content as a PDF.
            var pdf = renderer.RenderHtmlAsPdf(htmlContent);

            // Return a success result with the generated PDF.
            return PdfResult.CreateSuccess(pdf);
        }
        catch (Exception ex)
        {
            // Return a failure result with the error message if an exception occurs.
            return PdfResult.CreateFailure(ex.Message);
        }
    }
}

// Using directives for necessary namespaces.
using IronPdf;
using System;

// Define an abstract base class representing the PDF generation result.
public abstract class PdfResult
{
    // Private constructor to ensure the class cannot be instantiated directly.
    private PdfResult() { }

    // Nested class representing a successful PDF generation result.
    public sealed class Success : PdfResult
    {
        public PdfDocument Pdf { get; }

        public Success(PdfDocument pdf) => Pdf = pdf;

        public override string ToString() => "PDF generation succeeded";
    }

    // Nested class representing a failed PDF generation result.
    public sealed class Failure : PdfResult
    {
        public string ErrorMessage { get; }

        public Failure(string errorMessage) => ErrorMessage = errorMessage;

        public override string ToString() => $"PDF generation failed: {ErrorMessage}";
    }

    // Factory method to create a successful PDF result.
    public static PdfResult CreateSuccess(PdfDocument pdf) => new Success(pdf);

    // Factory method to create a failed PDF result.
    public static PdfResult CreateFailure(string errorMessage) => new Failure(errorMessage);
}

// Class to generate PDFs using IronPDF.
public class PdfGenerator
{
    // Method to generate a PDF from HTML content and return the result as a PdfResult.
    public PdfResult GeneratePdf(string htmlContent)
    {
        try
        {
            // Create a new ChromePdfRenderer instance.
            var renderer = new ChromePdfRenderer();

            // Attempt to render the HTML content as a PDF.
            var pdf = renderer.RenderHtmlAsPdf(htmlContent);

            // Return a success result with the generated PDF.
            return PdfResult.CreateSuccess(pdf);
        }
        catch (Exception ex)
        {
            // Return a failure result with the error message if an exception occurs.
            return PdfResult.CreateFailure(ex.Message);
        }
    }
}

' Using directives for necessary namespaces.
Imports IronPdf
Imports System

' Define an abstract base class representing the PDF generation result.
Public MustInherit Class PdfResult
	' Private constructor to ensure the class cannot be instantiated directly.
	Private Sub New()
	End Sub

	' Nested class representing a successful PDF generation result.
	Public NotInheritable Class Success
		Inherits PdfResult

		Public ReadOnly Property Pdf() As PdfDocument

		Public Sub New(ByVal pdf As PdfDocument)
			Me.Pdf = pdf
		End Sub

		Public Overrides Function ToString() As String
			Return "PDF generation succeeded"
		End Function
	End Class

	' Nested class representing a failed PDF generation result.
	Public NotInheritable Class Failure
		Inherits PdfResult

		Public ReadOnly Property ErrorMessage() As String

		Public Sub New(ByVal errorMessage As String)
			Me.ErrorMessage = errorMessage
		End Sub

		Public Overrides Function ToString() As String
			Return $"PDF generation failed: {ErrorMessage}"
		End Function
	End Class

	' Factory method to create a successful PDF result.
	Public Shared Function CreateSuccess(ByVal pdf As PdfDocument) As PdfResult
		Return New Success(pdf)
	End Function

	' Factory method to create a failed PDF result.
	Public Shared Function CreateFailure(ByVal errorMessage As String) As PdfResult
		Return New Failure(errorMessage)
	End Function
End Class

' Class to generate PDFs using IronPDF.
Public Class PdfGenerator
	' Method to generate a PDF from HTML content and return the result as a PdfResult.
	Public Function GeneratePdf(ByVal htmlContent As String) As PdfResult
		Try
			' Create a new ChromePdfRenderer instance.
			Dim renderer = New ChromePdfRenderer()

			' Attempt to render the HTML content as a PDF.
			Dim pdf = renderer.RenderHtmlAsPdf(htmlContent)

			' Return a success result with the generated PDF.
			Return PdfResult.CreateSuccess(pdf)
		Catch ex As Exception
			' Return a failure result with the error message if an exception occurs.
			Return PdfResult.CreateFailure(ex.Message)
		End Try
	End Function
End Class

$vbLabelText $csharpLabel

The PdfResult class represents a discriminated union with two cases: Success and Failure. The Success case contains a PdfDocument, while the Failure case holds an error message. The GeneratePdf method takes an HTML string, attempts to generate a PDF using IronPDF, and returns the result as a PdfResult. If PDF generation succeeds, it returns the Success case with the generated PDF. If an exception occurs, it returns the Failure case with the error message.

Conclusion

C# Discriminated Union (How It Works For Developers): Figure 2 - Licensing

Discriminated unions in C# provide a powerful and flexible way to model data with multiple possible cases. Although C# doesn't support discriminated unions, you can simulate them using class hierarchies, pattern matching, and other techniques. The resulting code is more type-safe, less error-prone, and easier to maintain.

IronPDF provides a free trial to help you get a feel for the software without any upfront costs. You can explore all the features and see how they align with your needs. After your trial, licenses are available starting at $799.

Preguntas Frecuentes

¿Cómo puedo crear una unión discriminada en C#?

Puedes crear una unión discriminada en C# definiendo una clase abstracta con subclases anidadas. Cada subclase representa un caso posible, como un estado de éxito o de error, y puedes usar el emparejamiento de patrones para manejar estos casos.

¿Cuál es el papel de la biblioteca de IronPDF en el manejo de uniones discriminadas?

La biblioteca de IronPDF se puede utilizar junto con uniones discriminadas para gestionar los resultados de generación de PDF. Al modelar estos resultados como uniones discriminadas, puedes asegurar la seguridad de tipos y manejar tanto las creaciones de PDF exitosas como cualquier error que ocurra.

¿Cómo mejora el emparejamiento de patrones las uniones discriminadas en C#?

El emparejamiento de patrones mejora las uniones discriminadas en C# al permitir a los desarrolladores manejar elegantemente cada caso posible. Con el emparejamiento de patrones, puedes gestionar de forma segura diferentes resultados, asegurando que todos los escenarios estén cubiertos en tiempo de compilación.

¿Por qué son beneficiosas las uniones discriminadas para la generación de PDF en C#?

Las uniones discriminadas son beneficiosas para la generación de PDF en C# porque proporcionan una manera estructurada de manejar casos de éxito y error. Este enfoque asegura que los problemas potenciales se aborden en tiempo de compilación, reduciendo los errores en tiempo de ejecución durante la creación del PDF.

¿Pueden las uniones discriminadas extenderse para funcionalidad adicional en C#?

Sí, las uniones discriminadas pueden extenderse con funcionalidad adicional usando métodos de extensión. Esto te permite agregar comportamientos personalizados, como verificar el estado de éxito de una generación de PDF, sin alterar la estructura base.

¿Existe una manera de simular uniones discriminadas en C# sin soporte nativo?

Sí, aunque C# no tiene soporte nativo para uniones discriminadas, se pueden simular usando jerarquías de clases. Una clase base abstracta puede usarse con clases anidadas para representar diferentes salidas posibles, como casos de éxito o fracaso.

¿Cómo manejan los desarrolladores de C# errores en la generación de PDF?

Los desarrolladores de C# pueden manejar los errores en la generación de PDF de manera efectiva usando uniones discriminadas para modelar los resultados potenciales. Este enfoque asegura que los errores se aborden en tiempo de compilación, mejorando la fiabilidad y mantenibilidad del código.

¿Cuáles son las ventajas de usar IronPDF con uniones discriminadas para proyectos en C#?

Usar IronPDF con uniones discriminadas en proyectos de C# ofrece la ventaja de un manejo robusto de errores durante la generación de PDF. Esta combinación permite una clara distinción entre operaciones exitosas y errores, mejorando la seguridad y fiabilidad del código.

¿Cómo contribuyen las uniones discriminadas a la seguridad de tipos en C#?

Las uniones discriminadas contribuyen a la seguridad de tipos en C# asegurando que todos los casos potenciales sean manejados durante la compilación. Esto reduce la probabilidad de errores en tiempo de ejecución y hace que el código sea más predecible y fácil de mantener.

Curtis Chau

Chatea con el equipo de ingeniería ahora

Escritor Técnico

Curtis Chau tiene una licenciatura en Ciencias de la Computación (Carleton University) y se especializa en el desarrollo front-end con experiencia en Node.js, TypeScript, JavaScript y React. Apasionado por crear interfaces de usuario intuitivas y estéticamente agradables, disfruta trabajando con frameworks modernos y creando manuales bien ...