Why does the WPF Presentation library wrap strings in StringBuilder.ToString()?

Question

The code found in the PresentationCore.dll (.NET4 WPF) by ILSpy:

// MS.Internal.PresentationCore.BindUriHelper internal static string UriToString(Uri uri) {     if (uri == null)     {         throw new ArgumentNullException("uri");     }      return new StringBuilder(uri.GetComponents(uri.IsAbsoluteUri ? UriComponents.AbsoluteUri : UriComponents.SerializationInfoString, UriFormat.SafeUnescaped), 2083).ToString(); } 

The return type of uri.GetComponents is string, why didn't the method just return the string value instead of wrapping it in a StringBuilder(string).ToString(); Is this by design? What would be the reason for doing this in a general sense? Would it reduce allocations or improve Garbage Collection or used for thread safety?

Answer 1

Only thing I can think of is that if the first parameter being passed into the stringBuilder is null, then the stringbuilder will return string.empty rather than null (see http://msdn.microsoft.com/en-us/library/zb91weab(v=vs.100).aspx)

A string is nullable though... so why bother?!

Just doing a check and returning an empty string yourself would be a lot more efficient than newing up a stringBuilder instance.

The second parameter is just a suggested size that the stringbuilder should be initialized to...

Comments on the OP's question are right, it appears to be overkill.