DLR Hosting and related stuff... : .NET FW & Runtime

Here's .NET framework 3.0

seshadripv — Sat, 10 Jun 2006 04:51:00 GMT

WinFX will hence be called .NET Framework 3.0. Read more about this at Soma's blog and find answers to some questions on this at jasonz's blog. Soma is the VP of Dev Div and Jason is the GM for the .NET FW – Dev FX group. So please let them have your whatever comments/feedback you have.

Power Toys - Develop Applications for .NET Framework 1.1 using Visual Studio 2005

seshadripv — Fri, 09 Jun 2006 17:47:00 GMT

I had earlier blogged about not being able to develop applications for .NET Framework 1.1 using Visual Studio 2005. Now there is some great news on this.

As part of the Microsoft’s Shared Source initiative ‘PowerToys V 1.0’ for VisualStudio 2005 was released recently. One of the components in that – "MSBee" enables developers to target .NET FW 1.1 using VisualStudio 2005. This means you don’t have to upgrade your .NET 1.1 apps just because you needed some of the cool new features in VisualStudio 2005. Check out a couple of other cool tools also – Team Foundation Server Admin Tool and Managed Stack Explorer.

System.FormatException while parsing a string containing valid integer values

seshadripv — Thu, 09 Mar 2006 16:25:00 GMT

Trying to convert a value to an integer using the Parse function might throw a "System.FormatException" with the following following call stack.

Unhandled Exception: System.FormatException: Input string was not in a correct format.
   at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
   at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
   at System.Int16.Parse(String s, NumberStyles style, NumberFormatInfo info)
   [...] ( application specific callstack)

This could arise from a call to one of the Convert.ToIntxx functions ( viz.,ToInt16, ToInt32, ToInt64) or the Intxx.Parse()( Int16.Parse, Int32.Parse or Int64.parse) . The exception is not thrown for any value other than 0.

This is due to corruption of a registry key's value that deals with globalization settings.

The registry key "sPositiveSign" under HKEY_CURRENT_USER\Control Panel\International should be blank for this to work correctly. If this is set to 0 the above exception will occur. Change this value to " " in the registry key to correct this exception.

Note that whenever the value that is parsed is the same as the value for the 'sPositiveSign' item this exception is thrown.

Auto increment the build number in the 'AssemblyVersion'

seshadripv — Tue, 20 Dec 2005 17:58:00 GMT

Q) How to auto-increment the build number of the ‘AssemblyVersion’ in a managed application?

A) Locate the AssemblyInfo.cs (or VB) file and make the following change - [assembly: AssemblyVersion("1.0.*")] – Voila!!! The assemblyversion should now automatically change after each build. However, be warned – changing the buildnumber in a class library would result in the recompilation of all dependent assemblies.

Serializing an object of the KeyValuePair Generic class

seshadripv — Wed, 02 Nov 2005 18:13:00 GMT

Consider the following piece of C# code running in .NET framework 2.0

static void Main(string[] args)
{
   List<KeyValuePair<string, int>> foobar = new List<KeyValuePair<string, int>>();
   foobar.Add(new KeyValuePair<string, int>("test1", 1));
   foobar.Add(new KeyValuePair<string, int>("test2", 2));

   XmlSerializer serializer = new XmlSerializer(typeof(List<KeyValuePair<string, int>>));
   using (Stream stm = File.Create("foo.txt"))
   {
      serializer.Serialize(stm, foobar);
   }
}

'KeyValuePair' is a new generic class that has been added to the .NET framework in version 2.0. BTW i think KeyValuePair is the second most natural and 'easy-to-guess-usage' name in programming jargon.( The hands down winner is 'int').

On successful execution the expected output is
<?xml version="1.0"?>
<ArrayOfKeyValuePairOfStringInt32 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
     <KeyValuePairOfStringInt32>
          <key>test1</key>
          <value>1</value>
     </KeyValuePairOfStringInt32>
     <KeyValuePairOfStringInt32>
          <key>test2</key>
          <value>2</value>
     </KeyValuePairOfStringInt32>
</ArrayOfKeyValuePairOfStringInt32>

But the output you would see is
<?xml version="1.0"?>
<ArrayOfKeyValuePairOfStringInt32 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<KeyValuePairOfStringInt32 />
<KeyValuePairOfStringInt32 />
</ArrayOfKeyValuePairOfStringInt32>

As we clearly see neither the value nor the key gets serialized. If you had played around with the beta bits of VS 2005 and .NET FW 2.0 you would have had the key and value serializing properly.

BTW, Robert Wlodarczyk(who runs this cool blog - http://blogs.msdn.com/rwlodarc/) ran in to this issue in his real world app and narrowed it down to the KeyValuePair. If you are a die hard Imaging and media fan excited about Avalon/WinFX, you've got to bookmark his blog.

The issue turns out to be the following
1) The 'key' and 'value' members are implemented as 'Read-only' properties in .NET FW 2.0. They dont have a set accessor method.
2) The XmlSerializer class, by design, will not serialize read-only properties. In other words, properties that don't have a set accessor will not be serialized using the XmlSerializer class. Note that, you can trick the serializer in to doing the job by having an 'empty' set accessor function for a property of your class.

From (1) and (2) it turns out that the KeyValuePair cannot be meaningfully serialized.
Also, You can suspect this to be the issue if you run in to cases of missing members during serialization of the Framework classes( or third party classes without source code).

5 quick questions on Custom Attributes

seshadripv — Wed, 19 Oct 2005 13:32:00 GMT

1) What are custom attributes?

Attributes are instances of a Type. Attributes are just like any other class object except that they allow some special syntax.

2) Are attributes an alternate way of specifying a base class for a class? Inside an attributed class can I call the attribute’s method just like a base class method?

No. Even from inside an attributed class we cannot call an attribute’s member function without having an attribute object( as in <object>.SomeMethod() ). This sounds like an obvious statement. But this shows that attributes are not ‘base classes’ and an attributed class doesn’t derive from the attribute class. Normally, we will be able to call the base class methods from inside a derived class without having any object( or by using the Base keyword).

3) So, How are attributes connected to a class?

Attributes are some kind of special MEMBERS of the attributed class. Attributes are native to .NET and they get their own semantics. However there don’t seem to be a direct way to access the attribute instances. We have to go through GetCustomAttributes function to get the attribute instance and invoke its methods. ILDasm comes up with this for an attribute

.custom instance void Attrib.MyAttrib::ctor() = ( 01 00 00 00 )

Attrib is the namespace, MyAttrib the attribute.

4) I have defined my attribute class and applied it to a class. Is that all?

There is no effect on just attributing a class unless somebody\something checks whether a particular attribute is present and do some action based on that. Its like marking a statement in C/C++ with a label. Unless somebody uses a ‘GOTO’ statement, the label is pretty much useless. Using the label alone has no effect on the code.

5) Can I apply attributes only to Classes?

Attributes can be applied to data and method members of a class also. This again means that attributes are some kind of a special entity in .NET and it really doesn’t have any counterparts in classic C++.

Refer to Applied Microsoft.NET Framework Programming by Jeffrey Richter for some excellent coverage on Attributes( and lot of other stuff.NET)