Awesome
EnumFastToStringDotNet
This is a Visual Studio C# source generator for automatically generating enum extension methods that implement a switch expression based ToString method. Why? The default enum ToString method implements a binary search which is great for large lists but becomes time and memory inefficient for a just a few items when compared to a switch expression. Binary search has an O(log n) while a switch expression in this case has a O(1).
You can thank Nick Chapsas on YouTube for making me aware of this. Check out his awesome video here: C#'s Enum performance trap your code is suffering from
Benchmark
Benchmark done with BenchmarkDotNet. You can run it for yourself by opening the solution in Visual Studio and running the samples/Benchmark project.
| Method | Mean | Error | StdDev | Gen 0 | Allocated |
|------------------------------- |----------:|----------:|----------:|-------:|----------:|
| NativeToString | 25.871 ns | 0.5217 ns | 0.4625 ns | 0.0057 | 24 B |
| SwitchStatementToString | 1.265 ns | 0.0512 ns | 0.0479 ns | - | - |
| SwitchExpressionToString | 1.399 ns | 0.0565 ns | 0.0529 ns | - | - |
| EnumFastToStringDotNetToString | 1.510 ns | 0.0224 ns | 0.0175 ns | - | - |
Quick Start
- Add source generator reference to your project
<ItemGroup>
<ProjectReference Include="path\to\EnumFastToStringDotNet.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
</ItemGroup>
- Add using statement
using EnumFastToStringGenerated;
- Add [FastToString] attribute to your enum
[FastToString]
public enum HumanStates
{
Idle,
Working,
Sleeping,
Eating,
Dead
}
- Call FastToString method
Console.Out.WriteLine(HumanStates.Dead.FastToString());
- The Automatically Generated Code
using System;
namespace EnumFastToStringGenerated
{
public static class EnumExtensions
{
public static string FastToString(this Namespace.HumanStates states)
{
return states switch
{
Namespace.HumanStates.Idle => nameof(Namespace.HumanStates.Idle),
Namespace.HumanStates.Working => nameof(Namespace.HumanStates.Working),
Namespace.HumanStates.Sleeping => nameof(Namespace.HumanStates.Sleeping),
Namespace.HumanStates.Eating => nameof(Namespace.HumanStates.Eating),
Namespace.HumanStates.Dead => nameof(Namespace.HumanStates.Dead),
_ => throw new ArgumentOutOfRangeException(nameof(states), states, null)
};
}
}
}
Custom Method Name
If you would like to use a different method name, you can do so with the attribute argument "MethodName".
[FastToString(MethodName = "CustomMethodName")]
public enum HumanStates
{
Idle,
Working,
Sleeping,
Eating,
Dead
}
Then you can call the method like this:
Console.Out.WriteLine(HumanStates.Dead.CustomMethodName());
Customizing Source Generator
You can customize the source generator by changing the const values in the EnumSwitchSourceGenerator.cs file.
//The namespace that the attribute and extension method classes are defined in
private const string NAMESPACE = "EnumFastToStringGenerated";
//The name of the attribute
private const string ATTRIBUTE_NAME = "FastToString";
//The name of the extension method
private const string EXTENSION_METHOD_NAME = "FastToString";