Merge pull request #392 from shaunmccarthy/master

[csharp/en] Added Interesting Features (and fixed / cleaned up other code)

1 files changed, 355 insertions, 229 deletions

diff --git a/csharp.html.markdown b/csharp.html.markdown
index 1471b833..8c15b86f 100644
--- a/csharp.html.markdown
+++ b/csharp.html.markdown
@@ -3,8 +3,8 @@ language: c#
 contributors:
     - ["Irfan Charania", "https://github.com/irfancharania"]
     - ["Max Yankov", "https://github.com/golergka"]
-	- ["Melvyn Laïly", "http://x2a.yt"]
-filename: LearnCSharp.cs
+    - ["Melvyn Laïly", "http://x2a.yt"]
+    - ["Shaun McCarthy", "http://www.shaunmccarthy.com"]
 ---
 
 C# is an elegant and type-safe object-oriented language that enables developers to build a variety of secure and robust applications that run on the .NET Framework.
@@ -23,7 +23,12 @@ Multi-line comments look like this
 // Specify namespaces application will be using
 using System;
 using System.Collections.Generic;
-
+using System.Data.Entity;
+using System.Dynamic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Net;
+using System.Threading.Tasks;
 
 // defines scope to organize code into "packages"
 namespace Learning
@@ -32,8 +37,8 @@ namespace Learning
     // you're allowed to do otherwise, but shouldn't for sanity.
     public class LearnCSharp
     {
-        // A console application must have a main method as an entry point
-        public static void Main(string[] args)
+        // BASIC SYNTAX - skip to INTERESTING FEATURES if you have used Java or C++ before
+        public static void Syntax() 
         {
             // Use Console.WriteLine to print lines
             Console.WriteLine("Hello World");
@@ -46,7 +51,6 @@ namespace Learning
             Console.Write("Hello ");
             Console.Write("World");
 
-
             ///////////////////////////////////////////////////
             // Types & Variables
             //
@@ -61,140 +65,83 @@ namespace Learning
             // (0 <= byte <= 255)
             byte fooByte = 100;
 
-            // Short - Signed 16-bit integer
-            // (-32,768 <= short <= 32,767)
+            // Short - 16-bit integer
+            // Signed - (-32,768 <= short <= 32,767)
+            // Unsigned - (0 <= ushort <= 65,535)
             short fooShort = 10000;
-
-            // Ushort - Unsigned 16-bit integer
-            // (0 <= ushort <= 65,535)
             ushort fooUshort = 10000;
 
-            // Integer - Signed 32-bit integer
-            // (-2,147,483,648 <= int <= 2,147,483,647)
-            int fooInt = 1;
+            // Integer - 32-bit integer
+            int fooInt = 1; // (-2,147,483,648 <= int <= 2,147,483,647)
+            uint fooUint = 1; // (0 <= uint <= 4,294,967,295)
 
-            // Uinteger - Unsigned 32-bit integer
-            // (0 <= uint <= 4,294,967,295)
-            uint fooUint = 1;
-
-            // Long - Signed 64-bit integer
-            // (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807)
-            long fooLong = 100000L;
+            // Long - 64-bit integer
+            long fooLong = 100000L; // (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807)
+            ulong fooUlong = 100000L; // (0 <= ulong <= 18,446,744,073,709,551,615)
+            // Numbers default to being int or uint depending on size.
             // L is used to denote that this variable value is of type long or ulong
-            // anything without is treated as int or uint depending on size.
 
-            // Ulong - Unsigned 64-bit integer
-            // (0 <= ulong <= 18,446,744,073,709,551,615)
-            ulong fooUlong = 100000L;
+            // Double - Double-precision 64-bit IEEE 754 Floating Point
+            double fooDouble = 123.4; // Precision: 15-16 digits
 
             // Float - Single-precision 32-bit IEEE 754 Floating Point
-            // Precision: 7 digits
-            float fooFloat = 234.5f;
-            // f is used to denote that this variable value is of type float;
-            // otherwise it is treated as double.
+            float fooFloat = 234.5f; // Precision: 7 digits
+            // f is used to denote that this variable value is of type float
 
-            // Double - Double-precision 64-bit IEEE 754 Floating Point
-            // Precision: 15-16 digits
-            double fooDouble = 123.4;
-			
-			// Decimal - a 128-bits data type, with more precision than other floating-point types,
-			// suited for financial and monetary calculations
-			decimal fooDecimal = 150.3m;
+            // Decimal - a 128-bits data type, with more precision than other floating-point types,
+            // suited for financial and monetary calculations
+            decimal fooDecimal = 150.3m;
 
             // Boolean - true & false
-            bool fooBoolean = true;
-            bool barBoolean = false;
+            bool fooBoolean = true; // or false
 
             // Char - A single 16-bit Unicode character
             char fooChar = 'A';
 
             // Strings -- unlike the previous base types which are all value types,
-			// a string is a reference type. That is, you can set it to null
-            string fooString = "My string is here!";
+            // a string is a reference type. That is, you can set it to null
+            string fooString = "\"escape\" quotes and add \n (new lines) and \t (tabs)";
             Console.WriteLine(fooString);
-			// You can access each character of the string with an indexer:
-			char charFromString = fooString[1]; // 'y'
-			// Strings are immutable: you can't do fooString[1] = 'X';
 
-            // formatting
+            // You can access each character of the string with an indexer:
+            char charFromString = fooString[1]; // 'y'
+            // Strings are immutable: you can't do fooString[1] = 'X';
+
+            // Compare strings with current culture, ignoring case
+            string.Compare(fooString, "x", StringComparison.CurrentCultureIgnoreCase);
+
+            // Formatting, based on sprintf
             string fooFs = string.Format("Check Check, {0} {1}, {0} {1:0.0}", 1, 2);
-            Console.WriteLine(fooFormattedString);
 
-            // formatting dates
+            // Dates & Formatting
             DateTime fooDate = DateTime.Now;
             Console.WriteLine(fooDate.ToString("hh:mm, dd MMM yyyy"));
 
-            // \n is an escaped character that starts a new line
-            string barString = "Printing on a new line?\nNo Problem!";
-            Console.WriteLine(barString);
-
-            // it can be written prettier by using the @ symbol
+            // You can split a string over two lines with the @ symbol. To escape " use ""
             string bazString = @"Here's some stuff
-    on a new line!";
-            Console.WriteLine(bazString);
-
-            // quotes need to be escaped
-            // use \" normally
-            string quotedString = "some \"quoted\" stuff";
-            Console.WriteLine(quotedString);
-
-            // use "" when strings start with @
-            string quotedString2 = @"some MORE ""quoted"" stuff";
-            Console.WriteLine(quotedString2);
+on a new line! ""Wow!"", the masses cried";
 
             // Use const or read-only to make a variable immutable
             // const values are calculated at compile time
             const int HOURS_I_WORK_PER_WEEK = 9001;
 
-            // Nullable types
-            // any value type (i.e. not a class) can be made nullable by suffixing a ?
-            // <type>? <var name> = <value>
-            int? nullable = null;
-            Console.WriteLine("Nullable variable: " + nullable);
-
-            // In order to use nullable's value, you have to use Value property
-			// or to explicitly cast it
-            DateTime? nullableDate = null; 
-			// The previous line would not have compiled without the '?'
-			// because DateTime is a value type
-			// <type>? is equivalent to writing Nullable<type>
-			Nullable<DateTime> otherNullableDate = nullableDate;
-			
-			nullableDate = DateTime.Now;
-            Console.WriteLine("Nullable value is: " + nullableDate.Value + " or: " + (DateTime) nullableDate );
-
-            // ?? is syntactic sugar for specifying default value
-            // in case variable is null
-            int notNullable = nullable ?? 0;
-            Console.WriteLine("Not nullable variable: " + notNullable);
-
-            // Var - compiler will choose the most appropriate type based on value
-			// Please note that this does not remove type safety.
-			// In this case, the type of fooImplicit is known to be a bool at compile time
-            var fooImplicit = true;
-
             ///////////////////////////////////////////////////
             // Data Structures
             ///////////////////////////////////////////////////
-            Console.WriteLine("\n->Data Structures");
 
-            // Arrays
+            // Arrays - zero indexed
             // The array size must be decided upon declaration
             // The format for declaring an array is follows:
             // <datatype>[] <var name> = new <datatype>[<array size>];
             int[] intArray = new int[10];
-            string[] stringArray = new string[1];
-            bool[] boolArray = new bool[100];
 
             // Another way to declare & initialize an array
             int[] y = { 9000, 1000, 1337 };
 
             // Indexing an array - Accessing an element
             Console.WriteLine("intArray @ 0: " + intArray[0]);
-
-            // Arrays are zero-indexed and mutable.
+            // Arrays are mutable.
             intArray[1] = 1;
-            Console.WriteLine("intArray @ 1: " + intArray[1]); // => 1
 
             // Lists
             // Lists are used more frequently than arrays as they are more flexible
@@ -202,28 +149,21 @@ namespace Learning
             // List<datatype> <var name> = new List<datatype>();
             List<int> intList = new List<int>();
             List<string> stringList = new List<string>();
-
-            // Another way to declare & initialize a list
-            List<int> z = new List<int> { 9000, 1000, 1337 };
-
-            // Indexing a list - Accessing an element
-            // Lists are zero-indexed and mutable.
-            Console.WriteLine("z @ 0: " + z[2]);
+            List<int> z = new List<int> { 9000, 1000, 1337 }; // intialize
+            // The <> are for generics - Check out the cool stuff section
 
             // Lists don't default to a value;
             // A value must be added before accessing the index
             intList.Add(1);
             Console.WriteLine("intList @ 0: " + intList[0]);
 
-
             // Others data structures to check out:
-            //
             // Stack/Queue
             // Dictionary (an implementation of a hash map)
+            // HashSet
             // Read-only Collections
             // Tuple (.Net 4+)
 
-
             ///////////////////////////////////////
             // Operators
             ///////////////////////////////////////
@@ -232,10 +172,7 @@ namespace Learning
             int i1 = 1, i2 = 2; // Shorthand for multiple declarations
 
             // Arithmetic is straightforward
-            Console.WriteLine("1+2 = " + (i1 + i2)); // => 3
-            Console.WriteLine("2-1 = " + (i2 - i1)); // => 1
-            Console.WriteLine("2*1 = " + (i2 * i1)); // => 2
-            Console.WriteLine("1/2 = " + (i1 / i2)); // => 0 (0.5 truncated down)
+            Console.WriteLine(i1 + i2 - i1 * 3 / 7); //
 
             // Modulo
             Console.WriteLine("11%3 = " + (11 % 3)); // => 2
@@ -266,7 +203,6 @@ namespace Learning
             Console.WriteLine(i--); //i = 1. Post-Decrementation
             Console.WriteLine(--i); //i = 0. Pre-Decrementation
 
-
             ///////////////////////////////////////
             // Control Structures
             ///////////////////////////////////////
@@ -291,50 +227,37 @@ namespace Learning
             // A simple if/else can be written as follows
             // <condition> ? <true> : <false>
             string isTrue = (true) ? "True" : "False";
-            Console.WriteLine("Ternary demo: " + isTrue);
-
 
             // While loop
             int fooWhile = 0;
             while (fooWhile < 100)
             {
-                //Console.WriteLine(fooWhile);
-                //Increment the counter
                 //Iterated 99 times, fooWhile 0->99
                 fooWhile++;
             }
-            Console.WriteLine("fooWhile Value: " + fooWhile);
 
             // Do While Loop
             int fooDoWhile = 0;
             do
             {
-                //Console.WriteLine(fooDoWhile);
-                //Increment the counter
                 //Iterated 99 times, fooDoWhile 0->99
                 fooDoWhile++;
             } while (fooDoWhile < 100);
-            Console.WriteLine("fooDoWhile Value: " + fooDoWhile);
 
-            // For Loop
-            int fooFor;
             //for loop structure => for(<start_statement>; <conditional>; <step>)
-            for (fooFor = 0; fooFor < 10; fooFor++)
+            for (int fooFor = 0; fooFor < 10; fooFor++)
             {
-                //Console.WriteLine(fooFor);
                 //Iterated 10 times, fooFor 0->9
             }
-            Console.WriteLine("fooFor Value: " + fooFor);
-			
-			// For Each Loop
+
+            // For Each Loop
             // foreach loop structure => foreach(<iteratorType> <iteratorName> in <enumerable>)
-			// The foreach loop loops over any object implementing IEnumerable or IEnumerable<T>
-			// All the collection types (Array, List, Dictionary...) in the .Net framework
-			// implement one or both of these interfaces.
-			// (The ToCharArray() could be removed, because a string also implements IEnumerable)
+            // The foreach loop loops over any object implementing IEnumerable or IEnumerable<T>
+            // All the collection types (Array, List, Dictionary...) in the .Net framework
+            // implement one or both of these interfaces.
+            // (The ToCharArray() could be removed, because a string also implements IEnumerable)
             foreach (char character in "Hello World".ToCharArray())
             {
-                //Console.WriteLine(character);
                 //Iterated over all the characters in the string
             }
 
@@ -356,20 +279,18 @@ namespace Learning
                 case 3:
                     monthString = "March";
                     break;
-				// You can assign more than one case to an action
-				// But you can't add an action without a break before another case
-				// (if you want to do this, you would have to explicitly add a goto case x
-				case 6:
-				case 7:
-				case 8:
-					monthString = "Summer time!!";
-					break;
+                // You can assign more than one case to an action
+                // But you can't add an action without a break before another case
+                // (if you want to do this, you would have to explicitly add a goto case x
+                case 6:
+                case 7:
+                case 8:
+                    monthString = "Summer time!!";
+                    break;
                 default:
                     monthString = "Some other month";
                     break;
             }
-            Console.WriteLine("Switch Case Result: " + monthString);
-
 
             ///////////////////////////////////////
             // Converting Data Types And Typecasting
@@ -384,46 +305,228 @@ namespace Learning
             // try parse will default to type default on failure
             // in this case: 0
             int tryInt;
-            int.TryParse("123", out tryInt);
+            if (int.TryParse("123", out tryInt)) // Funciton is boolean
+                Console.WriteLine(tryInt);       // 123
 
             // Convert Integer To String
             // Convert class has a number of methods to facilitate conversions
             Convert.ToString(123);
+            // or
+            tryInt.ToString();
+        }
 
-            ///////////////////////////////////////
-            // Classes And Functions
-            ///////////////////////////////////////
-
-            Console.WriteLine("\n->Classes & Functions");
-
-            // (definition of the Bicycle class follows)
+        ///////////////////////////////////////
+        // CLASSES - see definitions at end of file
+        ///////////////////////////////////////
+        public static void Classes()
+        {
+            // See Declaration of objects at end of file
 
             // Use new to instantiate a class
             Bicycle trek = new Bicycle();
 
             // Call object methods
-            trek.speedUp(3); // You should always use setter and getter methods
-            trek.setCadence(100);
+            trek.SpeedUp(3); // You should always use setter and getter methods
+            trek.Cadence = 100;
 
             // ToString is a convention to display the value of this Object.
-            Console.WriteLine("trek info: " + trek.ToString());
-
-            // Instantiate another new Bicycle
-            Bicycle octo = new Bicycle(5, 10);
-            Console.WriteLine("octo info: " + octo.ToString());
+            Console.WriteLine("trek info: " + trek.Info());
 
             // Instantiate a new Penny Farthing
             PennyFarthing funbike = new PennyFarthing(1, 10);
-            Console.WriteLine("funbike info: " + funbike.ToString());
+            Console.WriteLine("funbike info: " + funbike.Info());
 
             Console.Read();
         } // End main method
 
+        // CONSOLE ENTRY A console application must have a main method as an entry point
+        public static void Main(string[] args)
+        {
+            OtherInterestingFeatures();
+        }
+
+        //
+        // INTERESTING FEATURES
+        //
+        
+        // DEFAULT METHOD SIGNATURES
+
+        public // Visibility
+        static // Allows for direct call on class without object 
+        int // Return Type,
+        MethodSignatures(
+            int maxCount, // First variable, expects an int
+            int count = 0, // will default the value to 0 if not passed in
+            int another = 3,
+            params string[] otherParams // captures all other parameters passed to method
+        )
+        { 
+            return -1;
+        }
+
+        // Methods can have the same name, as long as the signature is unique
+        public static void MethodSignature(string maxCount)
+        {
+        }
+
+        // GENERICS
+        // The classes for TKey and TValue is specified by the user calling this function.
+        // This method emulates the SetDefault of Python
+        public static TValue SetDefault<TKey, TValue>(
+            IDictionary<TKey, TValue> dictionary, 
+            TKey key, 
+            TValue defaultItem)
+        {
+            TValue result;
+            if (!dictionary.TryGetValue(key, out result))
+                return dictionary[key] = defaultItem;
+            return result;
+        }
+
+        // You can narrow down the objects that are passed in 
+        public static void IterateAndPrint<T>(T toPrint) where T: IEnumerable<int>
+        {
+            // We can iterate, since T is a IEnumerable
+            foreach (var item in toPrint)
+                // Item is an int
+                Console.WriteLine(item.ToString());
+        }
+
+        public static void OtherInterestingFeatures()
+        {
+            // OPTIONAL PARAMETERS
+            MethodSignatures(3, 1, 3, "Some", "Extra", "Strings");
+            MethodSignatures(3, another: 3); // explicity set a parameter, skipping optional ones
+
+            // EXTENSION METHODS
+            int i = 3;
+            i.Print(); // Defined below
+
+            // NULLABLE TYPES - great for database interaction / return values
+            // any value type (i.e. not a class) can be made nullable by suffixing a ?
+            // <type>? <var name> = <value>
+            int? nullable = null; // short hand for Nullable<int>
+            Console.WriteLine("Nullable variable: " + nullable);
+            bool hasValue = nullable.HasValue; // true if not null
+
+            // ?? is syntactic sugar for specifying default value (coalesce)
+            // in case variable is null
+            int notNullable = nullable ?? 0; // 0
+
+            // IMPLICITLY TYPED VARIABLES - you can let the compiler work out what the type is:
+            var magic = "magic is a string, at compile time, so you still get type safety";
+            // magic = 9; will not work as magic is a string, not an int
+
+            // GENERICS
+            //
+            var phonebook = new Dictionary<string, string>() { 
+                {"Sarah", "212 555 5555"} // Add some entries to the phone book
+            };
+
+            // Calling SETDEFAULT defined as a generic above
+            Console.WriteLine(SetDefault<string,string>(phonebook, "Shaun", "No Phone")); // No Phone
+            // nb, you don't need to specify the TKey and TValue since they can be 
+            // derived implicitly
+            Console.WriteLine(SetDefault(phonebook, "Sarah", "No Phone")); // 212 555 5555
+
+            // LAMBDA EXPRESSIONS - allow you to write code in line
+            Func<int, int> square = (x) => x * x; // Last T item is the return value
+            Console.WriteLine(square(3)); // 9
+
+            // PARALLEL FRAMEWORK
+            // http://blogs.msdn.com/b/csharpfaq/archive/2010/06/01/parallel-programming-in-net-framework-4-getting-started.aspx
+            var websites = new string[] { 
+                "http://www.google.com", "http://www.reddit.com", 
+                "http://www.shaunmccarthy.com"
+            };
+            var responses = new Dictionary<string, string>();
+            
+            // Will spin up separate threads for each request, and join on them
+            // before going to the next step!
+            Parallel.ForEach(websites, 
+                new ParallelOptions() {MaxDegreeOfParallelism = 3}, // max of 3 threads
+                website =>
+            {
+                // Do something that takes a long time on the file
+                using (var r = WebRequest.Create(new Uri(website)).GetResponse())
+                {
+                    responses[website] = r.ContentType;
+                }
+            });
+
+            // This won't happen till after all requests have been completed
+            foreach (var key in responses.Keys)
+                Console.WriteLine("{0}:{1}", key, responses[key]);
+
+            // DYNAMIC OBJECTS (great for working with other languages)
+            dynamic student = new ExpandoObject();
+            student.FirstName = "First Name"; // No need to define class first!
+
+            // You can even add methods (returns a string, and takes in a string)
+            student.Introduce = new Func<string, string>(
+                (introduceTo) => string.Format("Hey {0}, this is {1}", student.FirstName, introduceTo));
+            Console.WriteLine(student.Introduce("Beth"));
+
+            // IQUERYABLE<T> - almost all collections implement this, which gives you a lot of 
+            // very useful Map / Filter / Reduce style methods
+            var bikes = new List<Bicycle>();
+            bikes.Sort(); // Sorts the array
+            bikes.Sort((b1, b2) => b1.Wheels.CompareTo(b2.Wheels)); // Sorts based on wheels
+            var result = bikes
+                .Where(b => b.Wheels > 3) // Filters - chainable (returns IQueryable of previous type)
+                .Where(b => b.IsBroken && b.HasTassles)
+                .Select(b => b.ToString()); // Map - we only this selects, so result is a IQueryable<string>
+
+            var sum = bikes.Sum(b => b.Wheels); // Reduce - sums all the wheels in the collection
+
+            // Create a list of IMPLICIT objects based on some parameters of the bike
+            var bikeSummaries = bikes.Select(b=>new { Name = b.Name, IsAwesome = !b.IsBroken && b.HasTassles });
+            // Hard to show here, but you get type ahead completion since the compiler can implicitly work
+            // out the types above!
+            foreach (var bikeSummary in bikeSummaries.Where(b => b.IsAwesome))
+                Console.WriteLine(bikeSummary.Name);
+
+            // ASPARALLEL
+            // And this is where things get wicked - combines linq and parallel operations
+            var threeWheelers = bikes.AsParallel().Where(b => b.Wheels == 3).Select(b => b.Name);
+            // this will happen in parallel! Threads will automagically be spun up and the 
+            // results divvied amongst them! Amazing for large datasets when you have lots of 
+            // cores
+
+            // LINQ - maps a store to IQueryable<T> objects, with delayed execution
+            // e.g. LinqToSql - maps to a database, LinqToXml maps to an xml document
+            var db = new BikeRespository();
+
+            // execution is delayed, which is great when querying a database
+            var fitler = db.Bikes.Where(b => b.HasTassles); // no query run
+            if (42 > 6) // You can keep adding filters, even conditionally - great for "advanced search" functionality
+                fitler = fitler.Where(b => b.IsBroken); // no query run
+
+            var query = fitler
+                .OrderBy(b => b.Wheels)
+                .ThenBy(b => b.Name)
+                .Select(b => b.Name); // still no query run
+
+            // Now the query runs, but opens a reader, so only populates are you iterate through
+            foreach (string bike in query) 
+                Console.WriteLine(result);
+            
+
+
+        }
 
     } // End LearnCSharp class
 
     // You can include other classes in a .cs file
 
+    public static class Extensions
+    {
+        // EXTENSION FUNCTIONS
+        public static void Print(this object obj)
+        {
+            Console.WriteLine(obj.ToString());
+        }
+    }
 
     // Class Declaration Syntax:
     // <public/private/protected/internal> class <class name>{
@@ -434,64 +537,88 @@ namespace Learning
     public class Bicycle
     {
         // Bicycle's Fields/Variables
-        public int cadence; // Public: Can be accessed from anywhere
-        private int _speed;  // Private: Only accessible from within the class
-        protected int gear; // Protected: Accessible from the class and subclasses
-        internal int wheels; // Internal: Accessible from within the assembly
-        string name; // Everything is private by default: Only accessible from within this class
+        public int Cadence // Public: Can be accessed from anywhere
+        {
+            get // get - define a method to retrieve the property
+            {
+                return _cadence;
+            }
+            set // set - define a method to set a proprety
+            {
+                _cadence = value; // Value is the value passed in to to the setter
+            }
+        }
+        private int _cadence;
+
+        protected virtual int Gear // Protected: Accessible from the class and subclasses
+        {
+            get; // creates an auto property so you don't need a member field
+            set;
+        }
+
+        internal int Wheels // Internal: Accessible from within the assembly
+        {
+            get;
+            private set; // You can set modifiers on the get/set methods
+        }
+
+        int _speed; // Everything is private by default: Only accessible from within this class. 
+                    // can also use keyword privatee
+        public string Name { get; set; }
 
         // Enum is a value type that consists of a set of named constants
-		// It is really just mapping a name to a value (an int, unless specified otherwise).
-		// The approved types for an enum are byte, sbyte, short, ushort, int, uint, long, or ulong.
-		// An enum can't contain the same value twice.
-        public enum Brand
+        // It is really just mapping a name to a value (an int, unless specified otherwise).
+        // The approved types for an enum are byte, sbyte, short, ushort, int, uint, long, or ulong.
+        // An enum can't contain the same value twice.
+        public enum BikeBrand
         {
             AIST,
             BMC,
-            Electra=42, //you can explicitly set a value to a name
+            Electra = 42, //you can explicitly set a value to a name
             Gitane
         }
         // We defined this type inside a Bicycle class, so it is a nested type
         // Code outside of this class should reference this type as Bicycle.Brand
 
-        public Brand brand; // After declaring an enum type, we can declare the field of this type
+        public BikeBrand Brand; // After declaring an enum type, we can declare the field of this type
 
         // Static members belong to the type itself rather then specific object.
-        static public int bicyclesCreated = 0;
         // You can access them without a reference to any object:
         // Console.WriteLine("Bicycles created: " + Bicycle.bicyclesCreated);
+        static public int BicyclesCreated = 0;
 
         // readonly values are set at run time
         // they can only be assigned upon declaration or in a constructor
-        readonly bool hasCardsInSpokes = false; // read-only private
+        readonly bool _hasCardsInSpokes = false; // read-only private
 
         // Constructors are a way of creating classes
         // This is a default constructor
-        private Bicycle()
+        public Bicycle() 
         {
-            gear = 1;
-            cadence = 50;
+            this.Gear = 1; // you can access mmebers of the object with the keyword this
+            Cadence = 50;  // but you don't always need it
             _speed = 5;
-            name = "Bontrager";
-            brand = Brand.AIST;
-            bicyclesCreated++;
+            Name = "Bontrager";
+            Brand = BikeBrand.AIST;
+            BicyclesCreated++;
         }
 
         // This is a specified constructor (it contains arguments)
         public Bicycle(int startCadence, int startSpeed, int startGear,
-                       string name, bool hasCardsInSpokes, Brand brand)
+                       string name, bool hasCardsInSpokes, BikeBrand brand) 
+            : base() // calls base first
         {
-            this.gear = startGear; // "this" keyword denotes the current object
-            this.cadence = startCadence;
-            this._speed = startSpeed;
-            this.name = name; // it can be useful when there's a name conflict
-            this.hasCardsInSpokes = hasCardsInSpokes;
-            this.brand = brand;
+            Gear = startGear; 
+            Cadence = startCadence;
+            _speed = startSpeed;
+            Name = name; 
+            _hasCardsInSpokes = hasCardsInSpokes;
+            Brand = brand;
         }
 
         // Constructors can be chained
-        public Bicycle(int startCadence, int startSpeed, Brand brand) :
-            this(startCadence, startSpeed, 0, "big wheels", true)
+        public Bicycle(int startCadence, int startSpeed, BikeBrand brand) :
+            this(startCadence, startSpeed, 0, "big wheels", true, brand)
         {
         }
 
@@ -501,27 +628,8 @@ namespace Learning
         // classes can implement getters and setters for their fields
         // or they can implement properties (this is the preferred way in C#)
 
-        // Method declaration syntax:
-        // <scope> <return type> <method name>(<args>)
-        public int GetCadence()
-        {
-            return cadence;
-        }
-
-        // void methods require no return statement
-        public void SetCadence(int newValue)
-        {
-            cadence = newValue;
-        }
-
-        // virtual keyword indicates this method can be overridden in a derived class
-        public virtual void SetGear(int newValue)
-        {
-            gear = newValue;
-        }
-
         // Method parameters can have default values.
-		// In this case, methods can be called with these parameters omitted
+        // In this case, methods can be called with these parameters omitted
         public void SpeedUp(int increment = 1)
         {
             _speed += increment;
@@ -541,12 +649,12 @@ namespace Learning
             get { return _hasTassles; }
             set { _hasTassles = value; }
         }
-		
-		// You can also define an automatic property in one line
-		// this syntax will create a backing field automatically.
-		// You can set an access modifier on either the getter or the setter (or both)
-		// to restrict its access:
-		public bool IsBroken { get; private set; }
+
+        // You can also define an automatic property in one line
+        // this syntax will create a backing field automatically.
+        // You can set an access modifier on either the getter or the setter (or both)
+        // to restrict its access:
+        public bool IsBroken { get; private set; }
 
         // Properties can be auto-implemented
         public int FrameSize
@@ -558,13 +666,13 @@ namespace Learning
         }
 
         //Method to display the attribute values of this Object.
-        public override string ToString()
+        public virtual string Info()
         {
-            return "gear: " + gear +
-                    " cadence: " + cadence +
-                    " speed: " + _speed +
-                    " name: " + name +
-                    " cards in spokes: " + (hasCardsInSpokes ? "yes" : "no") +
+            return "Gear: " + Gear +
+                    " Cadence: " + Cadence +
+                    " Speed: " + _speed +
+                    " Name: " + Name +
+                    " Cards in Spokes: " + (_hasCardsInSpokes ? "yes" : "no") +
                     "\n------------------------------\n"
                     ;
         }
@@ -573,9 +681,10 @@ namespace Learning
         public static bool DidWeCreateEnoughBycles()
         {
             // Within a static method, we only can reference static class members
-            return bicyclesCreated > 9000;
+            return BicyclesCreated > 9000;
         } // If your class only needs static members, consider marking the class itself as static.
 
+
     } // end class Bicycle
 
     // PennyFarthing is a subclass of Bicycle
@@ -586,20 +695,27 @@ namespace Learning
 
         // calling parent constructor
         public PennyFarthing(int startCadence, int startSpeed) :
-            base(startCadence, startSpeed, 0, "PennyFarthing", true)
+            base(startCadence, startSpeed, 0, "PennyFarthing", true, BikeBrand.Electra)
         {
         }
 
-        public override void SetGear(int gear)
+        protected override int Gear
         {
-            gear = 0;
+            get
+            {
+                return 0;
+            }
+            set
+            {
+                throw new ArgumentException("You can't change gears on a PennyFarthing");
+            }
         }
 
-        public override string ToString()
+        public override string Info()
         {
             string result = "PennyFarthing bicycle ";
             result += base.ToString(); // Calling the base version of the method
-            return reuslt;
+            return result;
         }
     }
 
@@ -624,7 +740,7 @@ namespace Learning
             damage += meters;
         }
 
-        public void Broken
+        public bool Broken
         {
             get
             {
@@ -632,24 +748,34 @@ namespace Learning
             }
         }
     }
-} // End Namespace
 
+    /// <summary>
+    /// Used to connect to DB for LinqToSql example. 
+    /// EntityFramework Code First is awesome (similar to Ruby's ActiveRecord, but bidirectional)
+    /// http://msdn.microsoft.com/en-us/data/jj193542.aspx
+    /// </summary>
+    public class BikeRespository : DbSet
+    {
+        public BikeRespository()
+            : base()
+        {
+        }
+
+        public DbSet<Bicycle> Bikes { get; set; }
+    }
+} // End Namespace
 ```
 
 ## Topics Not Covered
 
  * Flags
  * Attributes
- * Generics (T), Delegates, Func, Actions, lambda expressions
  * Static properties
  * Exceptions, Abstraction
- * LINQ
  * ASP.NET (Web Forms/MVC/WebMatrix)
  * Winforms
  * Windows Presentation Foundation (WPF)
 
-
-
 ## Further Reading
 
  * [DotNetPerls](http://www.dotnetperls.com)