Yahoo! I lost my Yahoo ID!

Well... I'm not sure if it is identity theft yet, but I lost my Yahoo! id vyas_b@yahoo.com. I've been using a STRONG password for the past decade but yet one fine morning yahoo refuses to log me on. The password retrieval page asked me for three pieces of information which I was unable to furnish as: 1. I may have given a wrong birthday (when Yahoo allowed you to edit your birthdays). 2. I am based out of India but I wanted my ID to be on Yahoo.com (as Yahoo was making life difficult for everyone and subtly pushing people towards getting a co.in ID). So I might have abbreivated my then current postal code to make it a 5 digit US zip. 3. To cap it all, it was an ID created for me by somebody else. I am still surprised I was using it for as long as I did. Bottomline: 1. I lost my whole bunch of email contacts in my messenger. a. OK. Not entirely true. I was able to retrieve all the Yahoo IDs of my active friends from C:\Program Files\Yahoo!\Messenger\Profiles\vyas_b\Archive\Messages. b. If you're one of them, please let me know by posting here. :) I also Orkut for your information. 2. I lost all my password emails. Now I have to change my passwords for all my other accounts [wherever I had registered on the web for news / purchases etc. etc.]. 3. I lost all my contacts 4. I have to change my primary personal email 5. And I discovered Google Apps for my domain!

New Blogger Woes

I'm trying to post some code after a LONG time! This "new" blogger is frustrating me. I wanted to post some code, which has <script> tags. It wouldn't let me. I downloaded Word Add-in hoping that would resolve the problem (as word automatically encodes HTML content). To no avail! The info that blogger word add-in doesn't work with the new blogger is hidden somewhere that I could find only AFTER I installed and struggled to login for sometime. Now, I'm blogging my woes instead of what I had to! Anyway, welcome back to blogging :)

Static Constructors

Static Constructors:

1. Cannot have parameters

static A(int i) {} // error CS0132: 'A.A(int)': a static constructor must be parameterless

1. Cannot have accessibility modifiers

public static A() {}; // error CS0515: 'A.A()': access modifiers are not allowed on static constructors

• Cannot be called explicitly


• Called when the class is loaded for the first time


• Run at most once per application domain


• Can be declared for a struct as well


• Execution is triggered by when an instance of the class is created or any of the static members of the class are referenced.


• For a type is run at most once per application domain.


• That are marked extern usually specifies a DllImport attribute.  Note that the keyword here is usually.   The compiler doesn’t mandate you to specify one.  It merely generates a warning when the following is compiled into a library or application.


• TestSC.cs(3,16): warning CS0626: Method, operator, or accessor 'A.A()' is marked external and has no attributes on it. Consider adding a DllImport attribute to specify the external implementation.  

public class A
{
     extern static A();
     static int i =2;
     public static void Main() { return; }

}

Upon execution of the application it throws a TypeLoadException:
Unhandled Exception: System.TypeLoadException: Could not load type 'A' from assembly 'TestSC, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' because the method '.cctor' has no implementation (no RVA).

1. When present in a class force the compiler to omit beforefieldinit declaration.  The following text discusses ramifications.

Verbatim from C# Specification v.1.0: If a static constructor exists in the class, execution of the static field initializers occurs immediately prior to executing that static constructor. Otherwise, the static field initializers are executed at an implementation-dependent time prior to the first use of a static field of that class

Program #1
//Whether field i or j would be initialized first is implementation dependant.
class A
{
     static int i = 2;
}

class B
{
     static int j = 5;
}


On ILDASM

.class public auto ansi beforefieldinit A
       extends [mscorlib]System.Object
{
} // end of class A


Program #2
class Test
{
     public static void Main()
     {
          System.Console.WriteLine(“j = {0}, i={1}”,B.j,A.i);
     }
}
class A
{
     static int i = 2;
     static A() {};
}

class B
{
     static int j = 5;
     static B() {};
}

Since B.j is used first, field ‘j’ is guaranteed to get initialized first.

On ILDASM

.class public auto ansi A
       extends [mscorlib]System.Object
{
} // end of class A


     





Note that there’s no beforefieldinit in the declaration:

1. Can have a return statement with no expression terminating it.

Usage:

1. Can be used to assign computed static fields and static readonly fields


2. To make sure that the type is not marked with beforefieldinit.

Explicit Interface Implementation

I was looking through my study notes when I came across several short programs I wrote sometimes ago that highlight important features of the C# language.  I’ll be posting the same in the coming posts with examples of when to use them.

//Explicit interface definition
//Be able to call an interface method ONLY through that interface

using System;

public class TestInterface : ITestInterface
{
     public void Method1()
     {
          Console.WriteLine("Method 1 Called");
     }     

     public void CallMethod1()
     {
          Method1();
     }
     public void CallMethod2()
     {
          ((ITestInterface)this).Method2();
          Method2();
     }


     ///ITestInterface implementation
     ///Two separate implementations of methods, both explicit and implicit
     

     //Explicit interface implementation
     void ITestInterface.Method2()
     {
          Console.WriteLine("Method 2 Called through ITestInterface");
     }

     //Implicit interface implementation
     public void Method2()
     {
          Console.WriteLine("Method 2 called through the class reference");
     }
}

public class InterfaceCaller
{
     public static void Main()
     {
          TestInterface ti = new TestInterface();
          ti.CallMethod1();
          ti.CallMethod2();
          ti.Method2(); //No such method compiler error if implicit interface implementation is omitted.
     }
}




public interface ITestInterface
{
     void Method1();
     void Method2();
}


Usage Scenarios:

• Explicit Interface Implementation: Restrict the method access to be through the defined interface only.


• While writing wrappers you want to restrict your team members to work only with the interface that you provide.  You may have earmarked the class for refactoring later.


• Both EII & III: Provide two different implementations of the same method.


• For me personally, this is dangerous.  Unless your specific situation demands that you employ this feature, it is better to leave this alone.

TIFF support for IE

IE 6.0 does not have support for TIFF built-in. Here's an useful ActiveX control from Alterna that enables TIFF support. Right click on the TIFF to view, select "Open With" and choose "Internet Explorer".

Bluetooth for VOIP

I've been in UK for the past couple of months on a business trip. What best way to be in touch with friends if not VOIP? The glich: No built-in mic on my laptop. When I was looking for a mic, I stumbled on a Bluetooth earpiece on Amazon. I also own a Sony Ericsson w800i mobile phone that needed this for quite sometime. Suddenly the brain wave: Why can't I use this bluetooth earpiece for VOIP? Amazon rescued me once again with the "People who bought this also bought" refrain. Belkin Bluetooth Adapter! I'm so impressed! I strongly recommend BBA for anybody who wants to use their bluetooth earpiece for VOIP. In 50 pounds, I was online in no time at all.

A Downloader

I was enthralled by the peugeot parking game . I wanted to have this game on my local machine so I could play this whenever I wanted to. I also have the faced the same problem when I'm browsing PDF documents on the Net that disallows saving. I wrote this simple C# program that did it for me. Thanks to .Net SDK 2.0, it's just a couple of lines of code: using System; using System.Net; using System.IO; public class Downloader { public static void Main(string [] args) { if(args.Length == 0 || args.Length > 2) { Console.WriteLine("Usage: Downloader <Url to download> <new filename>"); return; } WebClient client = new WebClient(); string filename = @".\" + Path.GetFileName(args[0]) ; if(args.Length ==2) filename = args[1]; client.DownloadFile(args[0], filename); } } Now, I can play the game whenever I want :)

Posting in Tamil

My system did not have any Tamil fonts. I installed Microsoft's Language Interface Pack. I'm able to use Tamil as a keyboard...ஆனால், now my damned windows interface has gone for a toss. I've been trying with the Language & Regional Options applet to change my UI language back to English to no avail! Windows XP is supposed to be having a "UI / menu language" listbox on the language tab. It's not there, I swear!

MS Word Woes

I've been editing a word document that I need to submit by EOD. This document is having lots of screenshots documenting an existing application. Now, word has an annoying habit of showing only blank spaces for the screenshots. I click them and it shows me an outline (a placeholder where the image is supposed to be!) The background refreshes are so bad that I have to click on the image each time and scroll up and down a couple of times to get it to show. It's maddening and I am getting madder by the minute.

ThreadStaticAttribute

I was experimenting with ThreadStaticAttribute.  A way to make available a new copy of class (note: not instance) variables to each of the threads running.

Static methods usually do not store state in class level variables for it would be shared by all other static methods too.  Unless marked ‘volatile’ two threads executing two different static methods on the same class could step on each other while assigning / reading from the variable.  Also, they get to share the copy of the state.  Now you could store state from a static method into “ThreadStatic” variables that only the same executing thread could see.  There’s a side effect though: If you happen to use a ThreadPool.  ThreadPool threads could be reused leading to state being visible when it isn’t supposed to be.  Well, you could always re-initialize before exiting.   The following example demonstrates that.

using System;
using System.Threading;

public class TestThreadStatic
{

     int completed = 0;
     public static void Main(string [] args)
     {
          TestThreadStatic tts = new TestThreadStatic();
          tts.StartTesting();
          while(tts.completed < 5)
          {
               Thread.Sleep(1000);
          }
     }


     public void StartTesting()
     {
          Console.WriteLine("Initial value of ticks at " +
" the beginning: {0}", ticks);
          for(int i = 0; i < 5; i++)
          {
               Console.WriteLine("Assigning work item {0}", i);
               ThreadPool.QueueUserWorkItem(ExecutedOnAThread, i);
          }

     }

     [ThreadStatic]
     private static long ticks;

     public void ExecutedOnAThread(object state)
     {
          string hashCode = Thread.CurrentThread.GetHashCode().ToString();
          //Initialize only once
          switch(ticks)
          {
               case 0:
                    Console.WriteLine("[{0}] A New Thread", hashCode);
                    ticks = -2;
                    break;
               case -1:
                    Console.WriteLine("[{0}] Thread reused", hashCode);
                    break;
               default:  // if ticks is -2
                    Console.WriteLine("[{0}] A supposedly new " +
                                   "thread is able to see "         +
"the old value {1}",
hashCode,
ticks);
                    break;
          }

          Console.WriteLine("[{0}] Ticks at starting: {1}"
, hashCode, ticks);
          ticks = DateTime.Now.Ticks;
          Console.WriteLine("[{0}] Ticks at End: {1}", hashCode, ticks);
          ticks = -1;

          //If sleep is reduced some of the threads would be reused
          Thread.Sleep(5000);
            completed++;
     }
}


Remember, the variable must be declared static.


Results (if running with a 5 second delay):


Initial value of ticks at the beginning: 0
Assigning work item 0
Assigning work item 1
Assigning work item 2
Assigning work item 3
Assigning work item 4
[3] A New Thread
[3] Ticks at starting: -2
[3] Ticks at End: 632691576162343750
[4] A New Thread
[4] Ticks at starting: -2
[4] Ticks at End: 632691576171406250
[5] A New Thread
[5] Ticks at starting: -2
[5] Ticks at End: 632691576176406250
[6] A New Thread
[6] Ticks at starting: -2
[6] Ticks at End: 632691576181406250
[7] A New Thread
[7] Ticks at starting: -2
[7] Ticks at End: 632691576186406250

If the delay is made 1 second:

Initial value of ticks at the beginning: 0
Assigning work item 0
Assigning work item 1
Assigning work item 2
Assigning work item 3
Assigning work item 4
[3] A New Thread
[3] Ticks at starting: -2
[3] Ticks at End: 632691595203906250
[3] Thread reused
[3] Ticks at starting: -1
[3] Ticks at End: 632691595213906250
[4] A New Thread
[4] Ticks at starting: -2
[4] Ticks at End: 632691595213906250
[5] A New Thread
[5] Ticks at starting: -2
[5] Ticks at End: 632691595218906250
[3] Thread reused
[3] Ticks at starting: -1
[3] Ticks at End: 632691595223906250

Software as a Service

Is Microsoft really behind in its initiatives with “Windows Live”? Since I was there when the world – at least the Java guys - called Microsoft.Net initiative as “vaporware”, I suspect that it really might not. Though Microsoft has enough resources to buy its way into this futurescape, I feel it doesn’t have to. Windows Update is by far the most effective way to deliver OS Updates and is a feat not matched by any “practical” Operating Systems. Microsoft gets notified when a program on your machine crashes. Yes, it merely gets posted for the end-user with no apparent benefit. For Microsoft? It builds a database on possible failures that its Windows Updates can “evolve” to learn to anticipate and suggest “solutions”. Software-as-a-service is an idea, if I remember correctly, is something I read having propounded by Bill Gates about quite sometimes in the past. Now, yeah, Microsoft may be trailing its competitors in delivering on that promise. But don’t underestimate Microsoft. It may be a behemoth but when it moves, it does so with surprising speed. And, it has all the right things going for it. It has the software - Windows, IE, Windows Media Player, Windows CE, Windows Mobile - and partnerships - with Noika, Palm(!), AOL (Heard Microsoft is trying to buy into it?) and million other deals not disclosed to the mere mortals to do it for them.

The Machines & Us

I've been a big fan of Kevin Kelly, the founder editor of the Wired Magazine, for quite a while. Recently, when I was in US, I had a chance to buy his book Out Of Control which I had partially read it on his website - again a while ago, I guess. Even after 11 years after its publication, the book hasn't lost its charm. I think it will not for another 5-10 years at the least. His book is what I would call "a book of ideas" and a book where he mulls what's learnt and makes educated guess on what it will be. I ran a search on Google news, and found his latest article here It talks about a WebOS, the all knowing intelligence that our Net will be, similar to the AIs in Arthur Clark & Stephen Baxter - my favorite science fiction author(s). It's a fitting analogy to compare the human brain to the Net. But what's the analogy of consciousness will be? The consciousness, unbeknownst to itself, commands the brain to do what it wants. Now, all the computers sit there interlinked...and does the consciousness emerge itself as it does in human brains? I think, we have not understood the origin of consciousness yet, no? You just have the infrastructure and bingo, the consciousness emerges? I'm not too widely read to even fathom that question. But it's interesting indeed for me to come out of my blogging slumber and record it. I've been an application developer for the past 10 years from dBase, Clipper to now .Net. Yeah, what would an application developer know! But, I think, I've read and intuitively understand enough to realize that Network and software that evolves is the future. I can easily imagine what Kelly points to - A Web that learns from the actions of its users - prosumers. Right now, the web is a tangle of standards: CGI, PHP, ASPX and ASP etc. They are mostly designed and written to serve up what their masters are meant to. We have protocols on how information travels on the web and how the handshake and the further response of the Web Server (a piece of software that requires a PC with an Operating System). What shall push the Web to become the Ultimate Observer? I do not know. The infrastructure - consciousness - for that, I feel, is yet to emerge.

Finding the angle between two clock hands

 

I had come across an URL couple of days back: http://www.karrels.org/Ed/ACM/ec97/prob_2.html where this problem of finding the angle between two clock hands was mentioned. I wrote the following C# code yesterday. This seems to work (at least for the test inputs posted on the page). Do let me know if there's a bug.

    1 using System;

    2 

    3 public class ClockProblem

    4 {

    5     #region Public Methods

    6 

    7     public static void Main(string[] args)

    8     {

    9         if (args.Length != 1)

   10         {

   11             Console.WriteLine("Usage: ClockProblem 12:00");

   12             return;

   13         }

   14         string[] time = args[0].Split(':');

   15         var hr = Convert.ToInt32(time[0]);

   16         var min = Convert.ToInt32(time[1]);

   17         var clock = new ClockProblem();

   18         Console.WriteLine(

   19             "Angle between two hands at hour {0} min {1} is {2}",

   20             time[0],

   21             time[1],

   22             clock.FindAngleBetweenHands(hr, min)

   23         );

   24     }

   25 

   26     public float FindAngleBetweenHands(int hour, int minute)

   27     {

   28         float minuteHandAngle, hourHandAngle, angle;

   29 

   30         //If it's 12 hour consider it 0 if(hour == 12) hour = 0;

   31         //Whole clock face has 360 degrees and hence for each minute,

   32         //the minute hand must move 6 degrees in clockwise direction

   33         minuteHandAngle = minute * 6;

   34 

   35         //A hour hand moves 30 degrees in an hour.

   36         //Hence (hour * 30) gives us the number of degrees it moves.

   37         //Also, the hour hand must move 0-30 degrees in accordance with

   38         //the number of minutes the minute hand is showing.

   39         //the hour hand moves 0.5f degrees per minute.

   40         //Adjust hour angle accordingly.

   41         hourHandAngle = (hour * 30) + (minute * 0.5f) ;

   42         angle = Math.Abs(hourHandAngle - minuteHandAngle);

   43 

   44         //The degrees must always be within 180 degrees meaning

   45         //3:00 & 9:00 PM both show 90 degrees. if(angle > 180)

   46         angle = 360 - angle;

   47         return angle;

   48     }

   49 

   50     #endregion

   51 }

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