Csharp In Detail Part2

C# in Detail Jon Jagger Software Trainer, Designer, Consultant www.jaggersoft.com jon @ jaggersoft.com { JSL } Part 2

Blatant Advert ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C# in Detail is also available as an instructor led course

Agenda ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

string C# Programming Fundamentals Objects Relationships Systems

string Type ,[object Object],[object Object],[object Object],s stack heap null @ t static void Main() { string s = null ; string t = "Hiker" ; ... t[0] = 'B' ; } Hiker compile time error

indexer ,[object Object],[object Object],[object Object],static void Func( string s) { for ( int i = 0; i != s.Length; i++) { char c = s[i]; Console.Write(c); } }

System.String ,[object Object],namespace System { public sealed class String ... { ... // static methods public static int Compare( string , string ); public static bool Equals( string , string ); public static string Format( string , params object []); ... // readonly property public int Length { get; } // readonly indexer public char this [ int index] { get; } // instance methods public int CompareTo( string ); public override bool Equals( object ); public new bool Equals( string ); ... } }

StringBuilder ,[object Object],namespace System.Text { public sealed class StringBuilder { public StringBuilder(); // read-write properties public int Length { get ; set ; } public int Capacity { get ; set ; } // read-write indexer public char this [ int index] { get ; set ; } // instance methods public StringBuilder Append(...); public StringBuilder Insert(...); public StringBuilder Remove( int , int ); public StringBuilder Replace(...); ... public override string ToString(); } }

string Literals ,[object Object],[object Object],[object Object],[object Object],"c:emp" @"c:emp" @"quote"" char" @" MP: we got a slug JC: does it talk? MP: yup JC: I'll have it" c: emp c:emp quote"char MP: we got a slug JC: does it talk? MP: yup JC: I'll have it

string Operators ,[object Object],[object Object],[object Object],[object Object],[object Object],IsTrue(s == t); IsTrue(s.Equals(t)); IsFalse(( object )s == ( object )t); s stack heap @ @ t Hiker Hiker IsTrue(s == t); IsTrue(s.Equals(t)); IsTrue(( object )s == ( object )t); s @ @ t Hiker

class C# Programming Fundamentals Objects Relationships Systems

class Declaration ,[object Object],class Pair { public int X, Y; }; optional semi-colon by convention public names start with an uppercase letter (PascalCasing) class Pair { private int x, y; } ...and private names start with a lowercase letter (camelCasing) class Pair { int x, y; } default access is private

object Creation ,[object Object],[object Object],[object Object],p stack ? .X .Y heap required static void Main() { Pair p; } static void Main() { Pair p = null ; } static void Main() { Pair p = new Pair(); } p null p @ 0 0

class Constructor ,[object Object],[object Object],[object Object],[object Object],class Pair { } you declare a default c'tor class Pair { public Pair( int x, int y) {...} } compiler declares a default c'tor class Pair { public Pair() { ... } } no one declares a default c'tor

: this(...) ,[object Object],[object Object],[object Object],class Point { public Point( int x, int y) : this (x, y, Colour.Red) { } public Point( int x, int y, Colour c) { ... } ... private int x, y; private Colour c; }

instance Fields ,[object Object],[object Object],[object Object],[object Object],class Point { public Point( int x, int y) { this .x = x; y = y; } ... private int x; private int y = 42; } no warning! OK OK OK

readonly Fields ,[object Object],[object Object],compile time errors class Pair { public Pair( int x, int y) { this .x = x; this .y = y; } public void Reset() { x = 0; y = 0; } private readonly int x, y; } this declares Pair as an immutable object

const Fields ,[object Object],[object Object],[object Object],class Pair { private const int x = 0, y = 0; } class BadFields { ... BadFields(...) { question = 9 * 6; } ... static const int answer = 42; ... const int question; ... const Pair origin = new Pair(); } OK compile time errors this declares Pair with no instance fields

static Fields ,[object Object],[object Object],[object Object],[object Object],[object Object],class Pair { ... static Pair origin; ... static Pair topLeft = new Pair(10,20); ... static AnyClass field; ... static string both = "Arthur"; } Pair p = new Pair(); ... F(p.Origin); // compile-time error F(Pair.Origin); // OK

static Constructor ,[object Object],[object Object],[object Object],[object Object],class GoodExample { static GoodExample() { origin = new Pair(0,0); } ...static readonly Pair origin; } OK class BadExample { public static GoodExample() { x = 42; } ...const int x; } compile time errors

Copy Parameters ,[object Object],[object Object],[object Object],[object Object],static void Method(Pair parameter) { parameter = new Pair(42,42); } static void Main() { Pair arg = new Pair(0,0); Console.WriteLine(arg.X); Method(arg); Console.WriteLine(arg.X); } 0 0

ref Parameters ,[object Object],[object Object],[object Object],[object Object],[object Object],static void Method( ref Pair parameter) { parameter = new Pair(42,42); } static void Main() { Pair arg = null ; //Console.WriteLine(p.X); Method( ref arg); Console.WriteLine(arg.X); } 42 Method( ref type [ ] array ) allowed

out Parameters ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],static void Method( out Pair parameter) { parameter = new Pair(42,42); } static void Main() { Pair arg; //Console.WriteLine(p.X); Method( out arg); Console.WriteLine(arg.X); } 42 Method( out type [ ] array ) allowed

in Parameters? ,[object Object],[object Object],[object Object],argument parameter optional required Copy ref out @ @ @ @ @@ @@ 0 0 initialize

[ ] Arrays C# Programming Fundamentals Objects Relationships Systems

Array Variables ,[object Object],[object Object],int [] row = null ; int [,] grid = null ; int [,,] threeD = null ; row stack heap null null grid

Array Instances ,[object Object],[object Object],[object Object],int [] row = new int [4]; int [,] grid = new int [2,3]; row stack heap @ @ grid 0 0 0 0 0 0 0 0 0 0 array of struct s

Array Initialisation ,[object Object],[object Object],[object Object],[object Object],int [] row = new int [4] {1,2,3,4}; int [,] grid = new int [,] { {1,2,3}, {4,5,6,}, }; int [,] shortcut = { {1,2,3}, {4,5,6} }; row stack heap @ @ grid 1 2 3 4 1 2 3 4 5 6 trailing commas are permitted

System.Array ,[object Object],namespace System { public class Array { protected Array(); ... // readonly properties public int Length { get; } public int Rank { get; } // instance methods public int GetLength( int ); // static methods public static void Clear(Array, int , int ); ... } } int [,] cosmic = { {1,2,3}, {4,5,6} }; Console.Write(cosmic.Length); Console.Write(cosmic.Rank); Console.Write(cosmic.GetLength(0)); Console.Write(cosmic.GetLength(1)); 6223

Using Arrays ,[object Object],[object Object],class Example { static void Use( int [,] grid) { int rowLength = grid.GetLength(0); int colLength = grid.GetLength(1); for (int row = 0; row != rowLength; row++) { for (int col = 0; col != colLength; col++) { Console.WriteLine(grid[row,col]); } } } static void Main() { Use( new int [,]{ {1,2,3}, {4,5,6} }); ... } } there is no direct way to make rowLength constant

Ragged Arrays ,[object Object],[object Object],[object Object],int [][] ragged = new int [3][ ]; int [][][] tatters = null ; ragged stack heap @ null null null tatters null

Ragged Initialisation ,[object Object],[object Object],int [][] ragged = new int [3][4]; int [][] ragged = new int [3][] { new int [2], null , new int [4]{ 1, 2, 3, 4 } }; ragged stack heap @ @ null @ 0 0 1 2 3 4 { ... } shorthand allowed here but not here compile time error

params type[ ] ,[object Object],[object Object],[object Object],static void GreyHole( params int [] row) { if (row != null ) Console.WriteLine(row.Length); else Console.WriteLine( "null" ); } static void Main() { GreyHole( null ); GreyHole(); GreyHole(1); GreyHole( new int []{1, 2}); GreyHole(1,2,3); } null 0 1 2 3 params is not part of the signature

params object[ ] ,[object Object],[object Object],[object Object],static void BlackHole( params object [] row) { if (row != null ) Console.WriteLine(row.Length); else Console.WriteLine( "null" ); } static void Main() { BlackHole( null ); BlackHole(); BlackHole(1M); BlackHole( new int []{1,2}); BlackHole(1, 2.0, "three" ); } null 0 1 1 3

Array Notes int [ ] illegal[ , ]; class Base {...} class Derived : Base {...} Derived[] ds = new Derived[]{...}; Base[] bs = ds; unsafe { int * array = stackalloc int [42]; ... } only one syntax C# supports array covariance you can create an array on the stack, but only in unsafe code object o = new int [42]; arrays are reference types int [ ][ , ] mixed; you can mix the two kinds of arrays

Boxing C# Programming Fundamentals Objects Relationships Systems

Recap ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],object value enum class interface [ ]array delegate struct value object object object @ @ @ @

struct vs class struct Pair { int x, y; ... } Pair p = new Pair(1,2); Pair copy = p; p.x stack heap class Pair { int x, y; ... } Pair p = new Pair(1,2); Pair copy = p; 1 2 @ p @ copy 1 2 p.y copy.x copy.y .x 1 2 .y

Objects Everywhere ,[object Object],[object Object],[object Object],System.Int32 « struct » System.ValueType « class » System.Enum « class » Suit « enum » Pair « struct » System.Object « class » int == System.Int32

Problem? ,[object Object],[object Object],[object Object],struct Pair { public int X, Y; ... } class Example { static object Dangle() { Pair p = new Pair(1,2); object o = p; return o; } static void Main() { object o = Dangle(); ... } } p.X stack 1 2 @ o p.Y ?

Boxed Solution ,[object Object],[object Object],[object Object],[object Object],the copy is the same plain bitwise copy used for value parameters/returns struct Pair { public int X, Y; ... } static void Function() { Pair p = new Pair(1,2); object o = p; } p.X stack heap 1 2 p.Y .X 1 2 .Y @ o box

Unboxing ,[object Object],[object Object],[object Object],struct Pair { public int X, Y; ... } static void Function() { Pair p = new Pair(1,2); object o = p; p.X = p.Y = 0; Pair q = (Pair)o; } p.X stack heap 0 0 p.Y .X 1 2 .Y @ o cast q.X 1 2 q.Y box unbox

System.Object ,[object Object],namespace System { public class Object { public Object(); public virtual bool Equals( object ); public virtual int GetHashCode(); public Type GetType(); public virtual string ToString(); ... } } static void AnySingleArgument( object accepted) { ... } any value variable (implicit boxing) any reference variable (implicit conversion)

No Overhead ,[object Object],[object Object],[object Object],[object Object],[object Object],Pair « struct » Object « class » Pair Reference « class » Int32 Reference « class » Int32 « struct » 42.ToString() is not a virtual call 1 1

Inheritance C# Programming Fundamentals Objects Relationships Systems

Extension ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],ViolinPlayer « class » Musician « class » class Musician { public void NotVirtual()... } class ViolinPlayer : Musician { ... }

: base(...) ,[object Object],[object Object],[object Object],[object Object],class Musician { public Musician( string name)... public void NotVirtual()... } class ViolinPlayer : Musician { public ViolinPlayer( string name) : base (name) { ... } }

Method Access ,[object Object],[object Object],[object Object],class GoodClass { public virtual void Alpha()... protected virtual void Beta()... private void Gamma()... } class BadClass { private virtual void Delta()... } struct GoodStruct { public void Alpha()... private void Gamma()... } struct BadStruct { protected void Beta()... }

virtual Methods ,[object Object],[object Object],[object Object],class Musician { ... public virtual void TuneUp() { ... } } class ViolinPlayer : Musician { public virtual void TuneUp() { ... } } this does not override TuneUp from the Musician class

override Methods ,[object Object],[object Object],[object Object],[object Object],class Musician { ... public virtual void TuneUp() { ... } } class ViolinPlayer : Musician { public override void TuneUp() { ... } } this does same access too

sealed Methods ,[object Object],[object Object],[object Object],[object Object],class Musician { ... public virtual void TuneUp() { ... } } class ViolinPlayer : Musician { public sealed override void TuneUp() { ... } } sealed is always used with override

new Methods ,[object Object],[object Object],[object Object],[object Object],class Musician { ... public virtual void TuneUp() { ... } } class ViolinPlayer : Musician { public new virtual void TuneUp() { ... } }

Table ,[object Object],struct class override no* yes sealed no yes new no* yes public yes yes protected no yes private yes yes virtual no yes only needed when overriding or hiding methods from System.ValueType

Interfaces C# Programming Fundamentals Objects Relationships Systems

interface ,[object Object],[object Object],[object Object],interface names should start with an I interface ITuneable { void TuneUp(); } interface IPluckable { void Pluck(); } IPluckable « interface » ITuneable « interface »

Multiple Interfaces ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],class Violin : Instrument , IPluckable , ITuneable { ... } IPluckable « interface » ITuneable « interface » Violin « class » Instrument « class »

I.I.I. ,[object Object],[object Object],[object Object],a class must implement all inherited interface methods interface ITuneable { void TuneUp(); } interface IPluckable { void Pluck(); } class Violin : IPluckable, ITuneable { public void TuneUp() { ... } public virtual void Pluck() { ... } ... }

E.I.I. ,[object Object],[object Object],[object Object],interface ITuneable { void TuneUp(); } interface IPluckable { void Pluck(); } class Violin : Instrument , IPluckable, ITuneable { void ITuneable.TuneUp() { ... } void IPluckable.Pluck() { ... } ... } consider inheriting two operations with the same signature you can mix III and EII

interface Property ,[object Object],[object Object],interface IButton { string Caption { get ; set ; } ... } class Button : IButton { public virtual string Caption { get { ... } set { ... } } ... private string caption; }

interface Indexer ,[object Object],[object Object],[object Object],interface IDictionary { string this [ string word ] { get ; set ; } ... } class Dictionary : IDictionary { public virtual string this [ string word ] { get { ... } set { ... } } ... }

is ,[object Object],[object Object],[object Object],static void GreyHole( object o) { if (o is IPluckable) { IPluckable ip = (IPluckable)o; ip.Pluck() ... } } static void Main() { GreyHole( new Violin()); GreyHole(42); } check once check twice cast

as ,[object Object],[object Object],[object Object],static void GreyHole( object o) { IPluckable ip = o as IPluckable; if (ip != null ) { ip.Pluck(); ... } } static void Main() { GreyHole( new Violin()); GreyHole(42); } check once

typeof ,[object Object],[object Object],[object Object],[object Object],static void Main() { Violin stradi = new Violin(); IPluckable ip = stradi; Type t1 = ip.GetType(); Type t2 = typeof (Violin); Type t3 = Type.GetType( "Violin" ); Console.WriteLine(t1 == t2); Console.WriteLine(t2 == t3); Console.WriteLine(( object )t1 == ( object )t2); Console.WriteLine(( object )t2 == ( object )t3); } True True True True

ref out ,[object Object],[object Object],[object Object],interface IPluckable { void Pluck(); } static void Replace( ref IPluckable instrument) { instrument = new Guitar(); } static void Create( out IPluckable instrument) { instrument = new Banjo(); }

Table ,[object Object],struct class override no* yes sealed no yes new no* yes public yes yes protected no yes private yes yes virtual no yes i'face no no yes no no no no

Abstract Classes C# Programming Fundamentals Objects Relationships Systems

abstract Classes ,[object Object],[object Object],[object Object],[object Object],abstract class Bar { ... private int instanceMethod() { ... } private int instanceField; } abstract class Foo : Bar { ... public static int StaticMethod() { ... } public static int StaticField; }

abstract Methods ,[object Object],[object Object],[object Object],[object Object],abstract class Foo : Bar { public abstract void Method(); ... }

abstract Notes ,[object Object],[object Object],[object Object],abstract class Bar { protected virtual void Method() { ... } ... } abstract class Foo : Bar { protected abstract override void Method(); ... }

sealed Classes ,[object Object],[object Object],[object Object],[object Object],[object Object],abstract class Foo : Bar { protected abstract Method(); } sealed class Wibble : Foo { protected override void Method() { ... } ... }

Table ,[object Object],struct class override no* yes sealed no yes new no* yes public yes yes protected no yes private yes yes virtual no yes i'face no no yes no no no no abstract yes yes yes yes yes no yes sealed yes yes yes yes yes yes no abstract no no no yes no

Another Table ,[object Object],override new sealed virtual 1 2 N N abstract • abstract N 3 N • virtual • N 4 override • N new • sealed modifier order is not significant

Exceptions C# Programming Fundamentals Objects Relationships Systems

System.Exception ,[object Object],namespace System { public class Exception ... { public Exception(); public Exception( string ); public Exception( string , Exception); ... public Exception InnerException { get ; } public virtual string Message { get ; } public virtual string StackTrace { get ; } ... public override string ToString(); ... } }

Hierarchy Exception ArithmeticException InvalidCastException DivideByZeroException OutOfMemoryException NullReferenceException OverflowException SystemException ... ExecutionEngineException IndexOutOfRangeException

throw ,[object Object],[object Object],class Matrix { public Matrix( int rowSize, int colSize) { ... } public Row this [ int index ] { get { BoundsCheck(index); ... } set { BoundsCheck(index); ... } } // validation private void BoundsCheck( int index) { if (index < 0 || index >= rows.Length) throw new IndexOutOfRangeException(); } // representation private Row[] rows; } don't forget the new

try catch ,[object Object],[object Object],[object Object],try { FileInfo source = new FileInfo(filename); int length = ( int )source.Length; char [] contents = new char [length]; ... } catch (SecurityException caught) { ... } catch (IOException caught) { ... } catch (OutOfMemoryException) { ... } catch { ... throw ; } name is optional general catch block

finally ,[object Object],[object Object],[object Object],[object Object],TextReader reader = null ; try { FileInfo source = new FileInfo(filename); int length = ( int )source.Length; char [] contents = new char [length]; reader = source.OpenText(); reader.Read(contents, 0, length); ... } ... finally { if (reader != null ) { reader.Close(); } } definite assignment rules, OK

Local Resources ,[object Object],[object Object],[object Object],[object Object],TextReader reader = null ; try { FileInfo source = new FileInfo(filename); int length = ( int )source.Length; char [] contents = new char [length]; reader = source.OpenText(); reader.Read(contents, 0, length); ... } ... finally { if (reader != null ) { reader.Close(); } }

using Statements ,[object Object],[object Object],[object Object],[object Object],using ( type variable = init) embedded - statement { type variable = init ; try { embedded - statement } finally { if ( variable != null ) { ((IDisposable) variable ).Dispose(); } } } precisely equivalent to

IDisposable struct AutoClosing : IDisposable { public AutoClosing(TextReader reader) { if (reader == null ) { throw new ArgumentNullException(); } target = reader; } public void Dispose() { target.Close(); } private readonly TextReader target; } interface IDisposable { void Dispose(); }

Preference? ... TextReader reader = source.OpenText(); using ( new AutoClosing(reader)) { reader.Read(contents, 0, length); ... } TextReader reader = null ; try { ... reader = source.OpenText(); reader.Read(contents, 0, length); ... } finally { if (reader != null ) { reader.Close(); } } Before... ...After

lock ,[object Object],[object Object],public class Monitor { public static void Enter( object ); public static void Exit( object ); ... } lock ( expression ) e mbedded - statement System.Threading.Monitor.Enter( expression ); try { embedded - statement } finally { System.Threading.Monitor.Exit( expression ) ; } precisely equivalent to ( expression is evaluated once)

Exception Notes ,[object Object],[object Object],[object Object]

Garbage Collection C# Programming Fundamentals Objects Relationships Systems

The Miracle of Birth ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Get that would you, Deidre....

Death ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Shall we take our cars?

Finalize ,[object Object],[object Object],[object Object],[object Object],[object Object],public class Resource { ... public void Dispose() { this .Finalize(); } protected override void Finalize() { ... } } compile time errors

Destructor ,[object Object],[object Object],[object Object],[object Object],[object Object],public class Resource { ... ~Resource() { //... } ... } public class Resource { ... protected override void Finalize() { //... base .Finalize(); } ... }

GC Notes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Nested Types C# Programming Fundamentals Objects Relationships Systems

Nested Types ,[object Object],[object Object],[object Object],class Outer { interface Space { } abstract class Reaches { } class Limits { } sealed class Hebrides { } struct Mongolia { } } internal access private access

Nested Access ,[object Object],[object Object],[object Object],[object Object],class Outer { public class Inner { private void peek(Outer can) { can.peek( this ); } } private void peek(Inner cannot) { cannot.peek( this ); } } OK Fails Outer.peek(Inner cannot) Inner.peek(Outer can)

Access Modifiers ,[object Object],[object Object],[object Object],internal protected internal private protected Y public Y non-nested Y Y Y Y nested Y protected OR internal

Semantics ,[object Object],[object Object],[object Object],[object Object],class Outer { ... class Nested { ... } ... } Outer.Nested « class » Outer « class » Outer$Inner « class » Outer « class » Outer.this 1 C#, C++ Java

Delegates C# Programming Fundamentals Objects Relationships Systems

delegate Type ,[object Object],[object Object],[object Object],[object Object],delegate void Func( string s); class Eg { public static void ForAll( string [] args, Func call) { foreach ( string arg in args) { call(arg); } } } Func is a type name

static Method ,[object Object],[object Object],delegate void Func( string s); ... class Test { static void Display( string s) { ... } static void Main( string [] args) { Eg.ForAll(args, new Func(Test.Display)); Eg.ForAll(args, new Func(Display)); } } note no ( ) create a delegate instance

Instance Method ,[object Object],[object Object],delegate void Func( string s); ... class Test { void Stash( string s) { ... } void NotMain( string [] args) { Eg.ForAll(args, new Func( this .Stash)); Eg.ForAll(args, new Func(Stash)); } }

Remember This? delegate void Method(); ... TextReader reader = source.OpenText(); using ( new Finally( new Method(reader.Close))) { reader.Read(contents, 0, length); ... } TextReader reader = null ; try { ... reader = source.OpenText(); reader.Read(contents, 0, length); ... } finally { if (reader != null ) { reader.Close(); } } ...After Before...

Finally public delegate void Method(); public struct Finally : IDisposable { public Finally(Method call) { if (call == null ) { throw new ArgumentNullException(); } this .call = call; } public override void Dispose() { call(); } private readonly Method call; }

Mulitcast delegate ,[object Object],[object Object],[object Object],delegate void Pred( string s); ... class Test { void DoThis( string s) { ... } static void ThenThat( string s) { ... } void Method( string arg) { Pred call = null ; call += new Pred( this .DoThis); call += new Pred(Test.ThenThat); ... call(arg); } }

delegate Notes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Events C# Programming Fundamentals Objects Relationships Systems

event Delegates ,[object Object],[object Object],[object Object],namespace System.Windows.Forms { public class Button : ... { ... public event EventHandler Click; ... ... protected void OnClick(EventArgs e) { if (Click != null ) { Click( this , e); } } ... } }

Event Delegates ,[object Object],[object Object],[object Object],namespace System { public delegate void EventHandler ( object sender, EventArgs e ); ... public class EventArgs { ... } }

Event Example ,[object Object],[object Object],using System; using System.Windows.Forms; class MyForm : Form { private void InitializeComponent() { openFile = new Button(); ... openFile.Click += new EventHandler(OpenFile); } protected void OpenFile( object sender, EventArgs e) { ... } private Button openFile; } Note case difference: openFile vs OpenFile

Event Properties ,[object Object],[object Object],[object Object],[object Object],[object Object],namespace System.Windows.Forms { public class Button : ... { ... public event EventHandler Click { add { ... } remove { ... } } ... } }

Namespaces C# Programming Fundamentals Objects Relationships Systems

namespace ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],namespace Accu { namespace Conference { ... } } namespace Informant { ... } namespace Accu.Conference { ... ... ... ... } namespace Informant { ... }

using Directive ,[object Object],[object Object],[object Object],using System; class Bar { ... } namespace Accu.Conference { using System.Collections; ... class Foo : Bar { static void Main(String[] args) { Console.Write(args[0]); } ... private Hashtable store; } }

using Alias ,[object Object],[object Object],[object Object],namespace CSharp { using Vector = System.Collections.ArrayList; class SourceFile { ... Vector tokens; } }

Namespace Notes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Assemblies C# Programming Fundamentals Objects Relationships Systems

Modules ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C:gt; csc ... /target:module ...

Assembly ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],physically or logically containing C:gt; csc ... /target:library ... C:gt; csc ... /addmodule:... C:gt; csc ... /target:exe /reference:...

Deployment ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Versioning ,[object Object],[object Object],[object Object],[object Object],<major>.<minor>.<build>.<revision> incompatible maybe compatible Quick Fix Engineering

Version Policy ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],... <BindingPolicy> <BindingRedir Name="Wibble" Originator="32ab4ba45e0a69a1" Version="*" VersionNew="6.1.1212.14" UseLatestBuildRevision="no"/> </BindingPolicy>

internal access ,[object Object],[object Object],[object Object],[object Object],an assembly of four classes public internal private

[Attributes] C# Programming Fundamentals Objects Relationships Systems

What Are They? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Attribute Class ,[object Object],[object Object],[object Object],... public sealed class DeveloperAttribute : System.Attribute { ... public DeveloperAttribute( string name) { ... } ... }

[ tag ] ,[object Object],[object Object],[DeveloperAttribute("Jon Jagger")] public struct ConstInt { public ConstInt( int value) { this .value = value; } public static implicit operator int (ConstInt from) { return from.value; } private readonly int value; }

Problem ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

AttributeUsage ,[object Object],[object Object],[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Interface)] public sealed class DeveloperAttribute : System.Attribute { ... public DeveloperAttribute( string name) { ... } ... }

Multiple Tags ,[object Object],[object Object],[AttributeUsage(AttributeTargets.Class | ..., AllowMultiple = true )] public sealed class DeveloperAttribute : System.Attribute { ... public DeveloperAttribute( string name) { ... } ... } [DeveloperAttribute("Jon Jagger")] [DeveloperAttribute("Patrick Jagger")] public struct ConstInt { ... }

Positional ,[object Object],[object Object],[object Object],... public sealed class DeveloperAttribute : System.Attribute { public DeveloperAttribute( string name) { ... } ... } [DeveloperAttribute("Jon Jagger")] public struct ConstInt { ... }

Named ,[object Object],[object Object],[object Object],[object Object],... public sealed class DeveloperAttribute : System.Attribute { public DeveloperAttribute( string name) ... ... public string TelExt { get {...} set {...} } } [DeveloperAttribute("Patrick Jagger")] [DeveloperAttribute("Jon Jagger", TelExt="4263")] public struct ConstInt { ... }

metadata ,[object Object],[object Object]

Notes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Reflection C# Programming Fundamentals Objects Relationships Systems

Terminology ,[object Object],[object Object],Reflection is the ability of a program to manipulate as data something representing the state of the program during its own execution. There are two apects to such manipulation: Introspection is the ability of a program to observe and therefore reason about its own state. Intercession is the ability of a program to modify its own execution state or alter its own interpretation or meaning. Both apects require a mechanism for encoding execution state as data; providing such an encoding is called reification Richard Gabriel, et al

Attributes ,[object Object],public sealed class DeveloperAttribute ... { ... public override string ToString() { ... } ... } public class Example { static void Main() { string typename = "ConstInt"; Type t = Type.GetType(typename); object [] atts = t.GetCustomAttributes( true ); foreach ( object att in atts) { Console.WriteLine(att); } } }

Remember This? TextReader reader = source.OpenText(); using ( new Finally(reader, "Close" )) { reader.Read(contents, 0, length); ... } TextReader reader = null ; try { ... reader = source.OpenText(); reader.Read(contents, 0, length); ... } finally { if (reader != null ) { reader.Close(); } } ...After

Finally using System; using System.Reflection; public struct Finally : IDisposable { public Finally( object target, string methodName) { this .target = target; this .methodName = methodName; } public void Dispose() { Type t = target.GetType(); MethodInfo method = t.GetMethod(methodName); if (method != null ) { t.InvokeMember( methodName, BindingFlags.InvokeMethod, target, new object [0] ); } } private readonly object target; private readonly string methodName; }

Summary ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Standards ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Bibliography ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Csharp In Detail Part2

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