Tawani's Blog Rants

Hoerdt

2011-09-13T10:58:00.001-07:00

Hoerdt, a photo by still tippin' on Flickr.

Hoerdt

Health Care Debate Analysis

2009-10-09T13:12:00.000-07:00

Just read one of the best analogy to the Health Care debate: Who is my neighbor? A lesson from the Fire Department.
http://substitute.livejournal.com/1922188.html

Kobe - A true "Worst Practices" ASP.NET MVC Example

2009-04-17T07:21:00.000-07:00

I never comment about such things but after reading going through Kobe, I believe Microsoft has finally put out a true "Worst Practices" and "How-not-to" develop an ASP.NET MVC application. Check out these detailed analysis:

High level overiview by Karl Seguin : Kobe - Oh Dear Lord Why?!

Low level analysis by Ayende Rahien : Kobe – In the nuts & bolts and don’t really liking it.

There is nothing worse for a coding newbie than to be mislead with such ridiculous "sample reference application" especially from Microsoft.

Topological Sorting and Cyclic Dependencies

2009-02-18T12:54:00.000-08:00

Recently I needed to re-arrange items in an array based on its dependencies? and also detect any cyclic dependency. To be more clear, consider the following:

Given the type:


class Field
{
    public string Name{get;set;}
    public string[] DependsOn{get;set;}
}

Let's say I have an array of Field items:


List<Field> fields = new List<Field>();
fields.Add(new Field() { Name = "FirstName" });
fields.Add(new Field() { Name = "FullName",
    DependsOn = new[] {"FirstName","LastName"}});
fields.Add(new Field() { Name = "Age",
    DependsOn = new[] { "DateOfBirth" } });
fields.Add(new Field() { Name = "LastName" });
fields.Add(new Field() { Name = "DateOfBirth" });

So clearly we get our items in the following order:

FirstName
FullName
Age
LastName
DateOfBirth

First question: What is the best way to re-arrange the items in my list/array so that dependent columns (FullName & Age) are placed after the columns they depend on i.e. something like this:

FirstName
LastName
FullName
DateOfBirth
Age

So fields like Age always come after DateOfBirth which it depends on.

Second question: How do you detect cyclic dependencies? i.e. when
Field1 depends on Field2 and
Field2 depends on Field3 and
Field3 depends on Field1
So we don't get caught in a circle.

The solution will be to sort the fields in topological order. Below is the C# sample code I adopted from the Java version found at: http://www.java2s.com/Code/Java/Collections-Data-Structure/Topologicalsorting.htm.


class TopologicalSorter
{
    #region - Private Members -

    private readonly int[] _vertices; // list of vertices
    private readonly int[,] _matrix; // adjacency matrix
    private int _numVerts; // current number of vertices
    private readonly int[] _sortedArray;

    #endregion

    #region - CTors -

    public TopologicalSorter(int size)
    {
        _vertices = new int[size];
        _matrix = new int[size, size];
        _numVerts = 0;
        for (int i = 0; i < size; i++)
            for (int j = 0; j < size; j++)
                _matrix[i, j] = 0;
        _sortedArray = new int[size]; // sorted vert labels
    }

    #endregion

    #region - Public Methods -

    public int AddVertex(int vertex)
    {
        _vertices[_numVerts++] = vertex;
        return _numVerts - 1;
    }

    public void AddEdge(int start, int end)
    {
        _matrix[start, end] = 1;
    }

    public int[] Sort() // toplogical sort
    {
        while (_numVerts > 0) // while vertices remain,
        {
            // get a vertex with no successors, or -1
            int currentVertex = noSuccessors();
            if (currentVertex == -1) // must be a cycle                
                throw new Exception("Graph has cycles");

            // insert vertex label in sorted array (start at end)
            _sortedArray[_numVerts - 1] = _vertices[currentVertex];

            deleteVertex(currentVertex); // delete vertex
        }

        // vertices all gone; return sortedArray
        return _sortedArray;
    }

    #endregion

    #region - Private Helper Methods -

    // returns vert with no successors (or -1 if no such verts)
    private int noSuccessors()
    {
        for (int row = 0; row < _numVerts; row++)
        {
            bool isEdge = false; // edge from row to column in adjMat
            for (int col = 0; col < _numVerts; col++)
            {
                if (_matrix[row, col] > 0) // if edge to another,
                {
                    isEdge = true;
                    break; // this vertex has a successor try another
                }
            }
            if (!isEdge) // if no edges, has no successors
                return row;
        }
        return -1; // no
    }

    private void deleteVertex(int delVert)
    {
        // if not last vertex, delete from vertexList
        if (delVert != _numVerts - 1)
        {
            for (int j = delVert; j < _numVerts - 1; j++)
                _vertices[j] = _vertices[j + 1];

            for (int row = delVert; row < _numVerts - 1; row++)
                moveRowUp(row, _numVerts);

            for (int col = delVert; col < _numVerts - 1; col++)
                moveColLeft(col, _numVerts - 1);
        }
        _numVerts--; // one less vertex
    }

    private void moveRowUp(int row, int length)
    {
        for (int col = 0; col < length; col++)
            _matrix[row, col] = _matrix[row + 1, col];
    }

    private void moveColLeft(int col, int length)
    {
        for (int row = 0; row < length; row++)
            _matrix[row, col] = _matrix[row, col + 1];
    }

    #endregion
}

So we can then test our code using something as below:


class Program
{
    public static void Main (string[] args)
    {
        List<Field> fields = new List<Field>();
        fields.Add(new Field() { Name = "FirstName" });
        fields.Add(new Field()
        {
            Name = "FullName",
            DependsOn = new[] { "FirstName", "LastName" }
        });
        fields.Add(new Field()
        {
            Name = "Age",
            DependsOn = new[] { "DateOfBirth" }
        });
        fields.Add(new Field() { Name = "LastName" });
        fields.Add(new Field() { Name = "DateOfBirth" });

        foreach (var field in fields)
        {
            Console.WriteLine(field.Name);
            if(field.DependsOn != null)
                foreach (var item in field.DependsOn)
                {
                    Console.WriteLine(" -{0}",item);
                }
        }

        Console.WriteLine("\n...Sorting...\n");

        int[] sortOrder = getTopologicalSortOrder(fields);

        for (int i = 0; i < sortOrder.Length; i++)
        {
            var field = fields[sortOrder[i]];
            Console.WriteLine(field.Name);
            if (field.DependsOn != null)
                foreach (var item in field.DependsOn)
                {
                    Console.WriteLine(" -{0}", item);
                }
        }

    }

    private static int[] getTopologicalSortOrder(List<Field> fields)
    {
        TopologicalSorter g = new TopologicalSorter(fields.Count);
        Dictionary<string, int> _indexes = new Dictionary<string, int>();

        //add vertices
        for (int i = 0; i < fields.Count; i++)
        {
            _indexes[fields[i].Name.ToLower()] = g.AddVertex(i);
        }

        //add edges
        for (int i = 0; i < fields.Count; i++)
        {
            if (fields[i].DependsOn != null)
            {
                for (int j = 0; j < fields[i].DependsOn.Length; j++)
                {
                    g.AddEdge(i,
                        _indexes[fields[i].DependsOn[j].ToLower()]);
                }
            }
        }

        int[] result = g.Sort();
        return result;

    }


    class Field
    {
        public string Name { get; set; }
        public string[] DependsOn { get; set; }
    }
}

Get a Random Date

2009-02-18T12:48:00.000-08:00


static DateTime GetRandomDate(Random rand, 
    DateTime minDate, DateTime maxDate)
{
    TimeSpan ts = maxDate - minDate;
    int totalDays = (int)ts.TotalDays;
    int randomDays = rand.Next(0, totalDays);
    return minDate.AddDays(randomDays);
}

Algarve

2007-11-08T10:26:00.001-08:00

nice place to be right now (winter)

algarve
Originally uploaded by coulportste.

Some truth about software consulting

2007-09-25T08:52:00.000-07:00

Somehow this poster [from Despair, Inc.] always makes a lot of sense.

Accidents de voiture : Tunnels Russe

2007-09-15T15:26:00.001-07:00

It must be the vodka!

The Bus Lane

2007-09-15T15:19:00.001-07:00

Always respect the bus lane .. or else ... well, see for yourselves

How to get a random date in C#

2007-09-12T09:17:00.000-07:00

I looked everywhere for a sample on generating random dates in C# but could find any so I wrote mine.


private static DateTime getRandomDate(Random rand, 
    DateTime minDate, DateTime maxDate)
{
    int totalDays = (int)DateTimeUtil.DateDiff(
        DateInterval.Day , minDate, maxDate);
    int randomDays = rand.Next(0,totalDays);
    return minDate.AddDays(randomDays);

}

This function uses the DateTime utility class below which I found somewhere on the web.


    public enum DateInterval
    {
        Day,
        DayOfYear,
        Hour,
        Minute,
        Month,
        Quarter,
        Second,
        Weekday,
        WeekOfYear,
        Year
    }

///


    public sealed class DateTimeUtil
    {

        #region DateDiff Methods

        public static long DateDiff(DateInterval interval, 
            DateTime dt1, DateTime dt2)
        {

            return DateDiff(interval, dt1, dt2, System.Globalization
                .DateTimeFormatInfo.CurrentInfo.FirstDayOfWeek);

        }

        private static int GetQuarter(int nMonth)
        {
            if (nMonth <= 3)
                return 1;
            if (nMonth <= 6)
                return 2;
            if (nMonth <= 9)
                return 3;
            return 4;
        }

        public static long DateDiff(DateInterval interval, 
            DateTime dt1, DateTime dt2, DayOfWeek eFirstDayOfWeek)
        {

            if (interval == DateInterval.Year)

                return dt2.Year - dt1.Year;

            if (interval == DateInterval.Month)

                return (dt2.Month - dt1.Month) + 
                    (12 * (dt2.Year - dt1.Year));

            TimeSpan ts = dt2 - dt1;

            if (interval == DateInterval.Day || 
                interval == DateInterval.DayOfYear)
                return Round(ts.TotalDays);

            if (interval == DateInterval.Hour)
                return Round(ts.TotalHours);

            if (interval == DateInterval.Minute)
                return Round(ts.TotalMinutes);

            if (interval == DateInterval.Second)

                return Round(ts.TotalSeconds);

            if (interval == DateInterval.Weekday)
            {
                return Round(ts.TotalDays / 7.0);
            }

            if (interval == DateInterval.WeekOfYear)
            {
                while (dt2.DayOfWeek != eFirstDayOfWeek)
                    dt2 = dt2.AddDays(-1);
                while (dt1.DayOfWeek != eFirstDayOfWeek)
                    dt1 = dt1.AddDays(-1);
                ts = dt2 - dt1;
                return Round(ts.TotalDays / 7.0);
            }

            if (interval == DateInterval.Quarter)
            {
                double d1Quarter = GetQuarter(dt1.Month);
                double d2Quarter = GetQuarter(dt2.Month);
                double d1 = d2Quarter - d1Quarter;
                double d2 = (4 * (dt2.Year - dt1.Year));
                return Round(d1 + d2);
            }
            return 0;
        }

        private static long Round(double dVal)
        {
            if (dVal >= 0)
                return (long)Math.Floor(dVal);
            return (long)Math.Ceiling(dVal);
        }
        #endregion
    }

Visual Studio is a memory hog - uses 1/2 a gig of memory

2007-09-06T12:47:00.000-07:00

Visual Studio (2005) and ASP.NET server are using more than 1/3 (765,304k) of all my memory. Has Microsoft lost its mind?

C# - How to check if a property type is an Enum

2007-07-03T10:39:00.001-07:00


class EnumTests
{
  public static void Run()
  {
      // convert a string into a color Enum
      Colour c = (Colour)Enum.Parse(typeof(Colour), "Red", true);
      Console.WriteLine("Colour Value: {0}", c.ToString());

      // Picking an invalid colour throws an ArgumentException. To
      // avoid this, call Enum.IsDefined() first, as follows:
      string nonColour = "OrangeGreen";

      if (Enum.IsDefined(typeof(Colour), nonColour))
          c = (Colour)Enum.Parse(typeof(Colour), nonColour, true);
      else
          Console.WriteLine("'{0}' is an undefined Color", nonColour);

      //Check if c is an Enum
      Console.WriteLine("c is an Enum = {0} ", c.GetType().IsEnum);
  }
}

#region Helper Classes

enum Colour
{
  Red,
  Green,
  Blue
}

#endregion

Yande, almost 10 weeks later.

2007-05-30T15:52:00.000-07:00

It's been almost 10 weeks since Yande was born, and he has almost double in size - about 16 lbs now. Anyway he wore shoes today and I thought I should take him some pictures.

Apollo Extensions for Flexbuilder 2.0.1 won't Install/Run

2007-03-20T18:01:00.000-07:00

After painstakingly downloading the new Apollo runtime and Apollo extensions for Flex Builder from Adobe Labs, I now have to deal with errors nobody at the Apollo forums seems to have any clue about. (Except another few 10s of developers who have the same problems).

I am running WinXP Pro SP2. During the Flex extensions install, I get to select the location of the Flex Builder folder and then I get an Eclipse Folder Error as shown below:

And I do not have Eclipse installed on this computer. I know Flex is built on Eclipse, but common, Adobe should be able to do better - I've been waiting for Apollo for too long.

The when I start Flex Builder, Apollo is present but still won't run.

I'm still watching the forums hoping somebody will answer this one.

Adobe.com is just Unacceptably TOO SLOW

2007-03-19T07:44:00.000-07:00

As a matter of fact, this site doesn't even load.

Today I received an email from adobe to download the alpha release for the highly anticipated Apollo SDK for building desktop apps that will run on Windows & Mac. But unfortunaly for the last 10 minutes, the site still hasn't loaded.
Adobe.com is notoriously slow especially when compared to other tech company sites such as Yahoo.com and Microsoft.com.

Adobe, I have 2 questions.
1. Why should I even bother about your software when your site would load?
2. Is your site running on ColdFusion?
Bonus
3. Add I hear you want to put Photoshop on the web, good luck.

Yande's Home Coming

2007-03-18T11:40:00.000-07:00

Yande and mother (Philo) finally came home on Thursday (3/15/2007). I will be putting up hist first home pictures later.
Apart from the Wheel Chair incident I still give Prince George's Hospital Center a solid “A” for their service. PG Hospital Center currently is run by Dimensions Healthcare System and I salute them for the excellent experience we had with their services. KUTGW.

Yande Franklin Anyangwe - First Pictures

2007-03-14T09:22:00.000-07:00

...more...

Since blogger does not provide a way to upload or manage a simple photo gallery, I have uploaded the pictures to my personal website at http://www.cityjams.com/yande

Yande Franklin Anyangwe 03/12/07

2007-03-13T07:21:00.000-07:00

Philo and I hereby welcome Yande F. Anyangwe into our family who arrived yesterday March 12th 2007 at 8lbs. 10oz.

Best Comparism: Ruby vs Java et al

2007-01-08T08:40:00.000-08:00

This is probably the best analogy I've seen comparing dynamic languages (like Ruby & JavaScript) to static object oriented languages (like C# & Java) by Joel on Software.

Also a good start to understand how to map (ConvertAll) and reduce (Fold) your code - MapReduce
http://www.joelonsoftware.com/items/2006/08/01.html

Serialize JavaScript objects to XML (for use with Ajax)

2006-12-27T20:55:00.001-08:00

The following 3 functions can be added to any JavaScript library to serialize objects to XML for use with Ajax.

--- serialize.js ---


Array.prototype.toXml = function(t){
    var s = new Array(), i, l = this.length, v;
    var t2 = (t.charAt(t.length-1)=='s')?t.substring(0,t.length-1):t;
   
    for(i=0;i<l;i++){
        v = this[i];
        switch (typeof v) {
            case 'undefined':
            case 'function':
            case 'unknown':break;
            case 'object':if(v!=null){s.push(v.toXml(t2));}break;
            case 'string':v = v.toXml();
            default:s.push('<'+t2+'>'+v+'');
        }
    }
    if(s.length>1)return '<'+t+'>'+s.join('')+'';
    return s;
};

Object.prototype.toXml = function(t){
    var sa = new Array(''), se = new Array('');
    if(!t) t=this._tagName||'object';
   
    for(var i in this){               
        if (this.hasOwnProperty(i) && i.charAt(0)!='_') {
            var v = this[i];
            switch (typeof v) {
                case 'undefined':
                case 'function':
                case 'unknown':break;
                case 'object':if(v!=null){se.push(v.toXml(i));}break;
                case 'string':v = v.toXml();
                default: sa.push(' '+i+'="'+v+'"');
            }
        }
    }
    var s = se.join('');
    return '<'+t+sa.join('')+((s!='')?'>'+s+'':'/>');
};

String.prototype.toXml = function(){
    return this.replace('&','&amp;').
      replace('<','&lt;').replace('>','&gt;').
      replace('\'','&apos;').replace('"','&quot;');
};

Sample Usage

<script language="javascript" src="serialize.js"></script>
<script language="javascript">


function Car(make,model,color){
    this.make  = make;
    this.model = model;
    this.color = color;
}

var cars = new Array();
cars.push(new Car('BMW','545i','Silver'));
cars.push(new Car('Toyota','Corrola','Red'));
cars.push(new Car('Honda','Accord','Black'));

//serialize to xml
alert(cars.toXml());

</script>

Note:
1. Private properties are prefixed with an underscore
2. You can add a default TagName for an object using the this._tagName property. For example in the Cars object above, you can add:

this._tagName = 'car';

...

Why use FireFox when you can use Opera?

2006-10-12T04:58:00.000-07:00

For the past couple of days I've been getting increasingly frustrated with FireFox because it eats up all of my memory. The tabbed browsing feature is a neccessity for me (I dare not install IE7). So I switched a couple of days ago to Opera which has all the features I need and a very small footprint. After two day, I can say nothing but wonder, Why use FireFox when you can use Opera?

In Stevey's word on Agile Programming

2006-09-28T13:15:00.000-07:00

Up until maybe a year ago, I had a pretty one-dimensional view of so-called "Agile" programming, namely that it's an idiotic fad-diet of a marketing scam making the rounds as yet another technological virus implanting itself in naive programmers who've never read "No Silver Bullet", the kinds of programmers who buy extended warranties and self-help books and believe their bosses genuinely care about them as people, the kinds of programmers who attend conferences to make friends and who don't know how to avoid eye contact with leaflet-waving fanatics in airports and who believe writing shit on index cards will suddenly make software development easier. ... more..
(I kind of agree)