Question

I know there are tools to count the number of classes i use in my code base, and this is a reasonable software engineering metric (e.g. average lines of code per class).

However i was idly wondering whether there are any tools to count the number of anonymous classes in the code base?

If so would this make an interesting software quality metric? e.g. i would probably be worried if i had more anonymous classes than normal classes though I’m not sure if i should be.

Answer 1

I don’t think the number of anonymous types is a useful metric, whether by itself or when compared with the number of named types. I also don’t know about any tools that measure this (that doesn’t mean they don’t exist, though).

To find out the number of anonymous types in a compiled assembly, you could use these facts about compiled anonymous types:

1. They have the [CompilerGenerated] attribute
2. Their name starts with <>f__AnonymousType (an unspeakable name in C#)
3. They have the [DebuggerDisplay] attribute with Type="<Anonymous Type>"

#1 by itself is not enough to identify an anonymous type. And I think you can’t rely on #2 or #3, since MS can decide to change them at any time and other compilers, like Mono C#, can use another style. But I think it’s the best you can do. Using #1 and #2, you could write a method that does what you want like this:

private static int ComputeNumberOfAnonymousTypes(Assembly assembly)
{
    return (from type in assembly.GetTypes()
            where Attribute.IsDefined(type, typeof(CompilerGeneratedAttribute))
                    && type.Name.StartsWith("<>f__AnonymousType")
            select type)
        .Count();
}

If you wanted to find out the number of anonymous files in a bunch of source code files, you would need C# parser. If you are willing to use pre-release software, I think this would be a good job for Roslyn, except it doesn’t support anonymous types yet.