Stupid little keys...: May 2016

Saturday 21 May 2016

Guid parsing - strange casing behavior

System.Guid is used quite often by .NET developers. For most of the scenarios that you encounter it works quite well. However consider the following code block:

string guidstr1 = "122F5113-FF7E-455D-8FF0-D79A2B830375";
string guidstr2 = "076e6c09-57b1-48da-836f-57d3646d8cb0";
Guid guid = Guid.NewGuid();
Console.WriteLine(guid);
guid = new Guid(guidstr1);
Console.WriteLine(guid);
guid = new Guid(guidstr2);
Console.WriteLine(guid);
Console.ReadLine();

Output:
edca0d0e-e62f-4c03-b41a-16cc9176df71
122f5113-ff7e-455d-8ff0-d79a2b830375
076e6c09-57b1-48da-836f-57d3646d8cb0

Did you expect the highlighted output? Parsed GUID has changed the casing of alphabets.

If you crack open ILSpy and checkout the implementation of Guid constructor, you can locate the line that tries to parse the Guid using a style option "any".

public Guid(string g)
{
    if (g == null)
    {
        throw new ArgumentNullException("g");
    }
    this = Guid.Empty;
    Guid.GuidResult guidResult = default(Guid.GuidResult);
    guidResult.Init(Guid.GuidParseThrowStyle.All);
    if (Guid.TryParseGuid(g, Guid.GuidStyles.Any, ref guidResult))
    {
        this = guidResult.parsedGuid;
        return;
    }
    throw guidResult.GetGuidParseException();
}

There are many styles supported for GUID but there is no option that can preserve casing of the value.

private enum GuidStyles
{
    None = 0,
    AllowParenthesis = 1,
    AllowBraces = 2,
    AllowDashes = 4,
    AllowHexPrefix = 8,
    RequireParenthesis = 16,
    RequireBraces = 32,
    RequireDashes = 64,
    RequireHexPrefix = 128,
    HexFormat = 160,
    NumberFormat = 0,
    DigitFormat = 64,
    BraceFormat = 96,
    ParenthesisFormat = 80,
    Any = 15
}

Interesting to know!!

Sunday 15 May 2016

Visual Studio 2015 crash : case # 1

Recently I ran into an interesting problem. One of my colleague was facing an issue with his Visual Studio 2015 crashes. As soon as he would launch VS on his machine, the VS application screen would freeze for some time and then the process would terminate automatically. So, we started looking around for clues in the EventLog. We noticed the following log reported when the VS crashed on the machine.

Application: devenv.exe

Framework Version: v4.0.30319

Description: The process was terminated due to an unhandled exception.

Exception Info: System.TypeLoadException

at Microsoft.VisualStudio.Shell.Connected.ConnectedUser.BaseUserContext+d__56.MoveNext()

at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].Start[[Microsoft.VisualStudio.Shell.Connected.ConnectedUser.BaseUserContext+d__56, Microsoft.VisualStudio.Shell.Connected, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]](d__56 ByRef)

at Microsoft.VisualStudio.Shell.Connected.ConnectedUser.BaseUserContext.GetProfileSessionTokenCredentialsAsync(Boolean, System.Threading.CancellationToken)

at Microsoft.VisualStudio.Shell.Connected.ConnectedUser.BaseUserContext+d__54.MoveNext()