Correct way to obtain base name of a generic type in .NET is through Substring?

Question

If I have this:

Type t = typeof(Dictionary<String, String>);

How do I get "System.Collections.Generic.Dictionary" as a string? Is the best/only way to do this:

String n = t.FullName.Substring(0, t.FullName.IndexOf("`"));

Seems kinda hackish to me though.

The reason I want this is that I want to take a Type object, and produce code that is similar to the one found in a C# source code file. I'm producing some text templates, and I need to add types as strings into the source, and the FullName property produces something like this:

System.Collections.Generic.Dictionary`2[[System.String, mscorlib, Version=2.0.0.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.String, mscorlib, Version=2.0.0.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089]]

instead of what I want:

System.Collections.Generic.Dictionary<System.String, System.String>

---

Edit: Ok, here's the final code, still seems a bit like a hack to me, but it works:

/// <summary>
/// This method takes a type and produces a proper full type name for it, expanding generics properly.
/// </summary>
/// <param name="type">
/// The type to produce the full type name for.
/// </param>
/// <returns>
/// The type name for <paramref name="type"/> as a string.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <para><paramref name="type"/> is <c>null</c>.</para>
/// </exception>
public static String TypeToString(Type type)
{
    #region Parameter Validation

    if (Object.ReferenceEquals(null, type))
        throw new ArgumentNullException("type");

    #endregion

    if (type.IsGenericType)
    {
        if (type.GetGenericTypeDefinition() == typeof(Nullable<>))
        {
            Type underlyingType = type.GetGenericArguments()[0];
            return String.Format("{0}?", TypeToString(underlyingType));
        }
        String baseName = type.FullName.Substring(0, type.FullName.IndexOf("`"));
        return baseName + "<" + String.Join(", ", (from paramType in type.GetGenericArguments()
                                                   select TypeToString(paramType)).ToArray()) + ">";
    }
    else
    {
        return type.FullName;
    }
}

Answer 1

AFAIK the internal notation for generics uses the `x notation to indicate the number of type parameters to the generic type. I.e. 2 indicates that the Dictionary needs two types to close it. It is the same notation used by ILDasm and Reflection.

Answer 2

The problem is that you want a language specific notation, in this case C#.

IL syntax:     [mscorlib]System.Collections.Generic.Dictionary`2<class [mscorlib]System.String, class [mscorlib]System.String>
C# syntax:     System.Collections.Generic.Dictionary<System.String, System.String>
VB.NET syntax: System.Collections.Generic.Dictionary(Of System.String, system.String)

Maybe you can call a language service to get the string you want, but you're probably better of with generating the string yourself.

Answer 3

You can use CodeDom to generate a more "normal" looking C#-style declaration.

CodeDomProvider csharpProvider = CodeDomProvider.CreateProvider("C#");
CodeTypeReference typeReference = new CodeTypeReference(typeof(Dictionary<string, int>));
CodeVariableDeclarationStatement variableDeclaration = new CodeVariableDeclarationStatement(typeReference, "dummy");
StringBuilder sb = new StringBuilder();
using (StringWriter writer = new StringWriter(sb))
{
    csharpProvider.GenerateCodeFromStatement(variableDeclaration, writer, new CodeGeneratorOptions());
}

sb.Replace(" dummy;", null);
Console.WriteLine(sb.ToString());

The above code has the following output:

System.Collections.Generic.Dictionary<string, int>

That should get you most of what you want without any custom type-stringifying code.

Answer 4

Is this closer to what you're looking for?

It uses CodeTypeReferenceExpression and doesn't require any further Substring or Replace calls:

var type = typeof(Dictionary<string, string>);
Console.WriteLine(TypeToString(type));

// ...

public static string TypeToString(Type type)
{
    if (type == null) throw new ArgumentNullException("type");

    var sb = new StringBuilder();
    using (var sw = new StringWriter(sb))
    {
        var expr = new CodeTypeReferenceExpression(type);

        var prov = new CSharpCodeProvider();
        prov.GenerateCodeFromExpression(expr, sw, new CodeGeneratorOptions());
    }
    return sb.ToString();
}