stakx / TypeNameFormatter

TypeNameFormatter is a small .NET library for formatting type names à la C#.

What is this good for?

Have you ever stumbled over the cryptic formatting of Type objects?

var someType = typeof(IEnumerable<int[]>);

Console.WriteLine(someType);
// => System.Collections.Generic.IEnumerable`1[System.Int32[]]

If you'd rather see something that looks more like a C# type name, then this library might be for you:

using TypeNameFormatter;

var someType = typeof(IEnumerable<int[]>);

Console.WriteLine(someType.GetFormattedName());
// => IEnumerable<int[]>

Formatting any Type involves more special cases than you might expect (such as generic types, nested types, multi-dimensional and jagged arrays, by-reference and pointer types). This library deals with all of those, so that you don't have to.

How do I use it?

By importing the TypeNameFormatter namespace, the following extension methods become available:

• stringBuilder.AppendFormattedName(Type type, [TypeNameFormatOptions options]):
  Appends a C#-formatted type name to the given StringBuilder.

• type.GetFormattedName([TypeNameFormatOptions options]):
  Returns a C#-formatted type name as a string. (This is a convenience method that does exactly the same as the above, using a throw-away StringBuilder.)

Both methods allow you to specify any combination of the following TypeNameFormatOptions flags:

• Namespaces:
  Namespaces should be included. (For example, System.Action instead of Action.)

• NoAnonymousTypes: Anonymous types should not have their "display class" name transformed to a more legible syntax. (For example, <>f__AnonymousType5<string, int> instead of {string Name, int Count}.)

• NoGenericParameterNames:
  Parameter names of an open generic type should be omitted. (For example, IEnumerable<> instead of IEnumerable<T>. Note that this setting does not affect closed generic types; their arguments are always included.)

• NoKeywords:
  Primitive types should not be mapped to their corresponding C# language keywords. (For example, Int32 instead of int.)

• NoNullableQuestionMark: Nullable types should not be formatted using C# question mark syntax. (For example, Nullable<int> instead of int?.)

• NoTuple: Value tuple types should not be formatted using C# tuple syntax. (For example, ValueTuple<bool, int> instead of (bool, int).)

But it doesn't format <some type> correctly!

If you think you've found a bug, please raise an issue so it can be looked into. (Make sure to mention the type that doesn't get formatted as expected.)

Alternatives

• If you're targeting the .NET Framework, you can use good old System.CodeDom (which isn't particularly fast, however):

  using Microsoft.CSharp;
  using System.CodeDom;
  
  static string GetFormattedName(this Type type)
  {
      using (var provider = new CSharpCodeProvider())
      {
          var typeReference = new CodeTypeReference(type);
          return provider.GetTypeOutput(typeReference);
      }
  }

• You could perhaps use Microsoft's .NET Compiler Platform (Roslyn), but that is a large library that can do much more than is needed.

Advanced usage

Configuration knobs for the source code distribution

The TypeNameFormatter.Sources NuGet package comes with a few MSBuild properties that you can set inside your project file (inside a <PropertyGroup>):

• <TypeNameFormatterInternal>:
  This property determines the visibility of the types provided by TypeNameFormatter:

  • If set to True (the default), they are declared internal.
  • If set to False, they are declared public.

• <TypeNameFormatterProjectNodeName>:
  This property determines the name under which TypeNameFormatter's single .cs file will appear in e.g. Visual Studio's Solution Explorer:

  • If set to TypeNameFormatter.cs (the default), a hidden linked file by that name will be added to your project's root.
  • If set to any other relative file path, a visible linked file will be added to your project.

For example:

<Project …>
  …
  <PropertyGroup>
    <!-- Make TypeNameFormatter's types `public` instead of `internal`: -->
    <TypeNameFormatterInternal>False<TypeNameFormatterInternal>

    <!-- Make a linked file `TypeNameFormatter.cs` show up in Solution Explorer
         under a folder node named `Utilities`: -->
    <TypeNameFormatterProjectNodeName>Utilities\TypeNameFormatter.cs</TypeNameFormatterProjectNodeName>
  </PropertyGroup>
  …
</Project>