Friday, August 16, 2013

Becoming an employable programmer

 Here is my take on this issue of becoming an employable programmer.
  1.  Learn and understand data structures and algorithms (searching , stacks,queues , shortest path , sorting etc)
  2.  Do not read books like pragmatic programming or books on how programming should be done. They just make you feel bad and give you low self esteem.
  3. Learn your own way and make mistakes at the beginning but since you want to learn and improve, your programs will become better and smarter. 
  4. Learn one language very well  so that you can write excellent code that solves problems. 
  5. Understand one database scripting language and how database works
  6. Know how the Internet works and it  commonly used terms
  7. You do not need to learn new language  besides the one you are learning.Learn  a new language when you really and truly understand one programming language .
  8. Learn javascript ,Css and Html
  9.  Build some real works stuff  that solves a problem . Choose a framework and your tools to use.
  10.  Master the framework inner workings
  11.  Practice , learn , read lots of code in projects that you think are really interesting . When you are is interested, the learning and understanding process is easier.
  12. Learn how to sell your skills and value you can create to an employer.
  13. Have a blog to monitor your progress and tell the world what you are good in and learning.
  14. Choose some top software developers and  read their blogs and have a role model in the programming world
  15.  Have a beer and watch programming or tech videos.
  16. Good self esteem and be humble
  17. Develop good communication skills
  18. Have a side project with clear goals
  19. Have fun with friends or family
  20. Learn touch typing.
  21. Have a side activity that makes you feel good and enjoy the the present moment.
  22. Give your self reward for a job well done.

Saturday, September 29, 2012

How to implement a simple IoC Container.

I have decided to take a topic related to software development and dig deeper and write about it on weekends. It will be my weekly learning and knowledge sharing. I have myside projects but its always cool and rewarding to understand how something really works. I do not only want to be a framework user but also a Framework contributor. This can only happen if you deep deeper most of the tools of software and language you use. For this week I want to see how easy is it to implement a simple IoC container that can be used in a project.

 What is an IoC container ?
IoC stands  for Inversion of Control and represents a design pattern used in software development. Wikipedia describes it as " a style of software construction where reusable code controls the execution of problem-specific code. It carries the strong connotation that the reusable code and the problem-specific code are developed independently, which often results in a single integrated application. Inversion of control as a design guideline serves the following purposes:

  • There is a decoupling of the execution of a certain task from implementation.
  • Every module can focus on what it is designed for.
  • Modules make no assumptions about what other systems do but rely on their contracts.
  • Replacing modules has no side effect on other modules. "

 What problem does it try to solve?
 Coupling and dependencies between objects .We let some other objects inject the object when we need it hence we are inverting the control of the process .Passing interfaces into classes and not real objects makes it easy to maintain, add and extend functions of a  feature in an application.

What are the basic prerequisites of building one?
  1. You need a container class.
  2.  In the container class you need a delegate ( A function on the fly!)
  3.  You need a dictionary data structure since you need to look up for keys before sending out objects
  4. Create a function to register the interfaces
  5. Create another function to resolve the interfaces
  6. Use the Container and do something with it.

 Before looking at the code you should understand some concepts like Interfaces, Generics and Delegates in C#. The goal is not build something that I will actually use for production code but just to see and learn the core and basic aspects of an IOC container. Here is the code of the whole project.

   
    /*IOC Container main class */
    public class MyIocContainer
    {
        public delegate object CreateInstance(MyIocContainer container);

        public Dictionary Factory;

        public MyIocContainer()
        {
            this.Factory = new Dictionary();
        }

        public void RegisterInterface(CreateInstance ci)
        {
            if (ci == null)
                throw new ArgumentNullException("ci");

            if (Factory.ContainsKey(typeof(T)))
                throw new ArgumentException("Type already registered");

            Factory.Add(typeof(T), ci);
        }
         
        public T Resolve()
        {
            if (!Factory.ContainsKey(typeof(T)))
                throw new ArgumentException("Type not registered");

            // retrieve the object from the dictionary
            var creator = Factory[typeof(T)];

            // call the delegate returning the object created
            return (T)creator(this);
        }      
    }

   // Create some interfaces to use
    public interface IDownloader
    {
        void GetWebSiteContents(string url);
    }

    public interface IExtractHtmlTags
    {
        void ExtractHtmlTags(string pWebsiteHtmlP);
    }

    // Create some classes to use the interfaces 
    public class WebSiteDownLoader : IDownloader
    {
        public void GetWebSiteContents(string url)
        {   //Some code using the webclient class
            Console.WriteLine("Call using the IoC container to load a website");
        }
    }
   
    public class ExtractHtmlTag : IExtractHtmlTags
    {
        public void ExtractHtmlTags(string websiteDataStream)
        {   
            // Some code here using Regex class<.*?>
            Console.WriteLine("Call using the IoC container to extract html tags");
        }
    }

    // Usage class for the interfaces to perform task.
    public class WebSiteTagRemover
    {
        private readonly IExtractHtmlTags _extractHtml;
        private readonly IDownloader _getWebSite;

     public WebSiteTagRemover(IExtractHtmlTags eTag, IDownloader loader)
        {
           _extractHtml = eTag;
            _getWebSite = loader;
        }

     public void PrintResults()
        {
          _getWebSite.GetWebSiteContents("http://ngalatalla.blogspot.se/");
          _extractHtml.ExtractHtmlTags("website html

");
        }
    }
 
  /*Finally execute and use the container Hooray!! */
internal class Program
    {
        private static void Main(string[] args)
        {   
         //Initiate the container
            var container = new MyIocContainer();

        //Register some interfaces to be used
           container.RegisterInterface(x => new WebSiteDownLoader());
           container.RegisterInterface(x => new ExtractHtmlTag());

      //Resolve the interfaces and get the objects mapped to them
            var getContents = container.Resolve();
            var extract = container.Resolve();

        //Do stuff with the interfaces
        var webTagRemover = new WebSiteTagRemover(extract, getContents);
        webTagRemover.PrintResults();
        }
    }

Results---

If you really want to use an IoC Container in any .Net project, you do not need to implement your own. There are much better options out there. Even if you think of implementing your own, I do not think you can implement any feature or features that they do not already have. They are even more mature and free to use in your projects. Here is a list I composed for some popular ones. I use Ninject in my personal projects because it is mature and easily configured. Choose your own based on your needs.
  Happy programming !

Thursday, April 26, 2012

It is time for Javascript . Are you ready to embrace it?


JavaScript is becoming more and more indispensable for any web developer to know. I have heard lost of bad and good stuff about JavaScript but I ask my self if they are not the programmers who write such bad  JavaScript code  are unpredictable or the differences in the JavaScript engines on various browsers makes us think the language is the problem .I have not  really done much JavaScript development  in my short and exciting career but  I think JavaScript works!! and you can see the power on  every client( mobile phones, tablets etc) connected to the web and needs a good experience. Some known JavaScript APIs are Jquery that  make it very easy to navigate the Dom , NodeJs for server and client development in JavaScript and finally I should not forget to mention Knockout Js which give you a clean way to write clean JavaScript code binned to your model using the MVVM pattern.

I bought my first JavaScript book Eloquent javascript after reading the online version of the book and I think it worth the money. It shows you how to think and code generally and in JavaScript. I am still reading and try to do solve the  assignments in the book before looking at the answers. Its really exciting to play with JavaScript learning about closures and the dynamic and functional nature of the language. I mostly write lots of C# and Jquery code at work but to understand Jquery well , one has to understand JavaScript because that's the source and the beginning.

I have been interested to learn  Html5 and I found it rather amazing how easily you can make an animation process with just a few lines of code. I think Html5 is awesome and is good some browsers now accept it. I hope this stays and combining Html5 , Javascript with SignalR that provides a duplex connection to the server one can do some amazing things in real time. May be i should just write a program to prove this.

I think every web developer can bear with me that there is so much  going on  in the web and is difficult to keep the pace with technologies coming and going. I think the key is know a lot of them but be a master in some of them you love. No matter what is going on the web there is only one language that can do all the magic and that is JavaScript. So maybe its time  for you to learn it to. As a developer, learning new stuff, reading and knowing new technologies should be part of your life style. submit to reddit

Thursday, March 22, 2012

Awesome stuff with C#5 and ASP.NET MVC 4

 I have been having a good  time watching these videos of one of my my favorite writers and developers  Steven Sanderson . These videos are all about the new  Asp.net 4 with Upshot, Knockout, WebApi and how they come together to make building Single page applications (SPA) faster and cleaner. The second video is about C#5  asynchronous operations and how this can be applied to web applications. The code to perform asynchronous calls to the database have been made less chunky and less complicated .Finally one also learns how asynchronous call work underneath and how duplex connection to the server are made and handled by SignalR.  You can read this article  Asynchronous scalable web applications with realtime persistent long running connections with SignalR.
I hope to put the  stuff I leanrt from these videos in my next application, Finally it seems as if there is no running away from JavaScript as a modern software developer who love web applications. Its time to embrace it  and have in your bag of tools. This could be a whole post on its own.
Here are the links to the videos.
submit to reddit

Wednesday, January 11, 2012

Personal development, passion and goals

 I should be proud of my achievements last year  because
  1. I had  my degree in Computer Science,
  2. Got  a good job ,
  3. Had my second child Eric
  4. And bought  a house.
 I had goals for last year and I got more than I could have ever thought of .All this was possible because  of hard work and good planning , being realistic and having a wonderful and supportive wife and  daughter .

Since the beginning of December we have been preparing and packing all our stuff into boxes that we shall take along with us to our new home.Yesterday as I was packing, I came across lots of my notes and code I  wrote when I was studying back in the university. Some of the code was good and I was impressed when  l looked at it and some where really crap and I could not even understand what it does.I ask my self if i really wrote this. I had really had a good laugh at my self. Anyway that was then. I will say I am a better coder now compared to then. I had a lot of passion and still do  but I had to pass my courses so passing my courses was more important than passion and I think its just logical. . I had some nice and though times and really enjoyed some programming courses like Compilier thoery , data structures and algorithims , Computer architecture, C and C++ programming ,web development with .Net and discrete mathematics.

Today I get paid for writing code, and solving complex problems and I consider a pass when my technical boss is happy about it, the customer get his or her problem solved , the code is understandable, clear and concise for the human being to read and understand.

This year I intend to blog more and learn more stuff , deepen my knowledge in some advanced stuff deploy an application to the web or build an app . Learn some real time programming.When will I  do this ? My spare time that I can really own for my self. I love and really enjoy what I do and hope you also do. If you do not, then its time for you to be real to yourself and deepen your knowledge in what you love to do and have passion for. Its never to late to learn and everything is possible.

Thursday, November 10, 2011

Using recursion to do permutations

Solving problems using recursion.
 I have always had problems in understanding deep and complex recusion eventhough they all follow a common pattern that  is There is always a base case to stop the recursion and making a recursive call on some smaller part of the solution, I decided to set my bar high . Here are the things i set to use recursion to understand complex recursive calls .

  1. Solving Sudoku using Backtracking
  2. The Chess  Knight - Queen classic
  3. Permutations
  4. More problems as I come across.

Let start with the case that allows you to select all possible combinations of all members a set. I learnt that this recursive pattern in very important to understand because the is a common pattern used in solving the problems that I mentioned above and many others like searching and solving word puzzles
  Permutation
  I define  permutations as all the ways to arrange a set of items for example if you permute the word {cat} you get {cat, tac, act, atc, tca, cta}. Permutations are mathematical and if you want a deeper understanding of this then go to Permutation. in Wikepidia and read more
In the program below  the program does  permutation recursively . I am writing this because I feel I have started getting the power of recursion and how to solve problems with them. The truth is i understood the classical recursive  examples in the university like  Fibonacci ,factorials and the towers of Hanoi  but when it came to complex recursive example like the one below. I got a headache in thinking recursively.
 Here are the tough questions to answer when writing a program that does permutations.

  1. How do you just pick one element on the set and know which one to attach next? 
  2. How do you avoid doubles and repeating each elements?
  3. How do you separate them? 
  4. How do you know that all the possible combinations of the set have been made?
Here is the program written in C# that does permutations .


class Program
    {
        static void Main(string[] args)
        {
            Permutate("ABCD");
        }
        public static void RecPermute(string permutateHolder , string itemToPermutate)
        {
            if (itemToPermutate== string.Empty)
            {
                Console.WriteLine(permutateHolder);
            }
            else
            {
                for (int i = 0; i < itemToPermutate.Length; i++)
                {   // Get the rest of the items remaining in the set
                    var remaining = itemToPermutate.Substring(0, i) + itemToPermutate.Substring(i+1);
               //Take each element from the item and do a recursive call on them
                    RecPermute(permutateHolder + itemToPermutate[i], remaining);                    
                }
            }
        }

        // Wrapper for permutate function
        public static void Permutate(string item)
        {
            RecPermute("", item);
        }
    }
Here is part of the recursive tree of the program Permutate("ABCD").It show permutations for all elements beginning with the letter A.The other elements of the set follow the same pattern.
Happy programming !

Wednesday, November 9, 2011

Using design patterns to build part of a soccer game engine

My goal here is to see if  I can use and understand design patterns and use them to solve a real world problem. I started by first learning the singleton pattern  and used it in my Dynamic quiz application using ASP.net MVC and Entity Framework Code First. I want to design a soccer game engine .Its a big a complex problem to solve but the best way to solve such a problem is to divide it into smaller parts that contains all components of building a soccer game engine. For this post I will focus on the problem of letting the referees  and players know the current position of the ball always .I play soccer and love soccer so lets get real now to see what will be needed for this
  • A soccer game must have a ball
  • They are 11 players in each team
  • There are two teams
  • Two  lines men and one referee
  • Each team has reserve players
  • There is the playground of course
The ball is the center of attention and  everybody of interest for that game wants to know where the ball is and whats happening to it . Who  are the watchers  of the ball ?
Here is where the first problem comes in .
How do I solve the problem where the referees and players know the current position and get updates of  the ball position  as its played on the field.
Lets define some  real objects needed to solve the problem
  1. Ball
  2. Players
  3. Playground
  4. Referee
  5. Team
Now that we have  some real soccer objects you will find on every soccer game. We need to  create some logical objects (objects that connect the real world objects and use  programming logical controls and give them  some life)


 The Game object defines a football game by  putting all components needed for a soccer game together like the players , ball etc...
The SoccerGame object will simply simulate  a football game.


Here is an abstract view of the system as I have described above.


Using design patterns is not the first thing you think when you  want to solve a problem but  they provide good software design principles that have stood the test of time thanks to the "Gang of Four"(GOF). Any way you can read more about this here design patterns. Since I want to know how to actually use them the best way is to try to use them in real world scenario.

I am a visual person so the best way  to see the problem is to get a visual of the problem .Here  is the way i see it below
The pattern that fits this is the Observer pattern which says that "Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically." In our case  all objects are dependent on the ball for a  soccer game and  the players, referees  must be notified and updated  as it changes state(moving).
The observer pattern in its raw state is shown below




The next step is to put the soccer problem in the context of the  observer pattern  and  this time there is  a position  object in three dimensions(x,y,z)  to connect to the change of the ball state since it describes  the current position on the play ground. Changes of the state of the ball is reflected by the position .It is the state that every observer has be notified and interested  about.


The subject is the soccer ball
The concrete object is the actual football that will be kicked
The observers are the players and referees and they  implement the IObserver interface.


The ball must have a list of observers
The observers have a pointer to the football object
The positions of  all the participants with the ball in the game has to be known.


Now how do we implement this in  C# ? Here is where I have to shut my mouth and get a prototype of the game engine for my customer.


Here is the code of the Game Engine only .It brings everything together

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SoccerGame
{  
    /// 
    /// Simulating  part of a soccer game using the Observer pattern
    /// 
    public class GameEngine
    {

        public static void Main()
        {
            // Create our ball (the ConcreteSubject)
            var ball = new FootBall();

            // Create few players ( some ConcreteObservers)
            var messi = new Player(ball, "Messi");
            var etofils = new Player(ball, "Etofils");
            var Ibrahimmovic = new Player(ball, "Ibrahimovic");

            // Create some referees (also ConcreteObservers)
            var collina = new Referee(ball, "Collina");
            var ngala = new Referee(ball, "Ngala");

            Console.WriteLine();

            // Attach them with the ball
            ball.AttachObserver(messi);
            ball.AttachObserver(etofils);
            ball.AttachObserver(Ibrahimmovic);
            ball.AttachObserver(collina);
            ball.AttachObserver(ngala);
            Console.WriteLine(" After attaching the observers...");

            // Update the position of the ball. 
            // At this point, all the observers should be notified
            ball.SetBallPosition(new Position());
            Console.WriteLine();


            // Remove some observers
            ball.DetachObserver(etofils);
            ball.DetachObserver(collina);
            Console.WriteLine(" After detaching the refree Collina and Etofils from the ball...");


            // Updating the position of ball again
            // At this point, all the observers should be notified
            ball.SetBallPosition(new Position(10, 10, 30));
            // Press any key to continue....more things happen
            Console.Read();
        }
    }
}
That is it for now and happy programming !