ErrorOrValue

A minimalistic library that provides a simple wrapper around traditional try-catch blocks. Instead of throwing exceptions, it returns them as values, making error handling more explicit and easier to work with. This pattern allows you to handle both synchronous and asynchronous operations without the usual verbosity of exception handling, and it gives you full control over expected exceptions and custom exception transformations.

Key Features

• Minimalistic wrapper around try-catch: No additional complexity, just a straightforward mechanism for handling exceptions as values.

• Handle void methods: Run actions that return either null when successful, or an Exception if one occurs.

• Handle functions: Execute functions that return either a result value or an exception, wrapped in an ErrorOr type.

• Custom exception transformation: Supply a catch handler to transform the caught exception into a specific exception type.

• Specify expected exceptions: Provide a list of exception types to catch. If the thrown exception is not in the list, it is rethrown as usual.

• Async support: All functionalities are also available for asynchronous Task-returning methods, keeping your async code clean and consistent.

Installation

Via the nuget package manager:

Install-Package ErrorOrValue

Or via the .NET CLI:

dotnet add package ErrorOrValue

Basic Usage

Running Actions

Call a void-returning action that might throw:

using ErrorOrValue; Exception? error = ErrorOr.Try(() => { // Your code that may throw exceptions }); if (error is not null) { // Handle the exception }

You can also specify which exceptions you expect. If a thrown exception isn't listed, it will be rethrown:

Exception? error = ErrorOr.Try(() => { // Your code }, typeof(ArgumentException), typeof(InvalidOperationException) );

Running Functions with Return Types

Execute a function with a return type and get either a result or an exception:

using ErrorOrValue; using ErrorOrValue.Results; ErrorOr<int> result = ErrorOr.Try(() => { // Your code that returns an int }); if (result.IsSuccess) { int value = result.Value; // Use the value } else { Exception caught = result.Error; // Handle the exception } // Or with deconstruction var (error, user) = ErrorOr.Try(GetUser); if (error is not null) { // Handle the exception }

Transforming Exceptions with a Catch Handler

You can provide a custom handler to transform the caught exception into a specific exception type:

CustomException? customError = ErrorOr.Try(() => { // Your code }, ex => new CustomException("Custom message", ex) );

For functions that return values:

ErrorOr<string, CustomException> result = ErrorOr.Try(() => { // Your code returning a string }, ex => new CustomException("Custom message", ex) ); if (result.IsSuccess) { string value = result.Value; } else { CustomException customEx = result.Error; // Handle the transformed exception } // Or with deconstruction var (customError, customer) = ErrorOr.Try( () => GetCustomer(), ex => new CustomException("Custom message", ex) );

Async Support

All of these patterns also work asynchronously:

Exception? asyncError = await ErrorOr.TryAsync(async () => { // Your async code that may throw }); ErrorOr<int> asyncResult = await ErrorOr.TryAsync(async () => { // Your async code returning int }); // Or with deconstruction var (customError, customer) = await ErrorOr.TryAsync( GetCustomerAsync, ex => new CustomException("Custom message", ex) );

As with synchronous methods, you can specify expected exceptions or provide a custom catch handler for asynchronous functions as well.

API Overview

• Try(Action action, params Type[]? expectedExceptions)
• Try<TException>(Action action, Func<Exception, TException> catchHandler)
• Try<TResult>(Func<TResult> func, params Type[]? expectedExceptions)
• Try<TResult, TException>(Func<TResult> func, Func<Exception, TException> catchHandler)

And their async counterparts:

• TryAsync(Func<Task> func, params Type[]? expectedExceptions)
• TryAsync<TException>(Func<Task> func, Func<Exception, TException> catchHandler)
• TryAsync<TResult>(Func<Task<TResult>> func, params Type[]? expectedExceptions)
• TryAsync<TResult, TException>(Func<Task<TResult>> func, Func<Exception, TException> catchHandler)

ErrorOr<TResult> and ErrorOr<TResult, TException> provide a clean, value-based approach to checking for success or failure without relying on thrown exceptions.

License

This project is licensed under the MIT License.