в 15:31, 26 мая 2010

2010-05-26T15:31:19Z

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2010-05-26T11:45:47Z

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==a generic delegate being initialized with a normal method==

<source lang="csharp">
using System;
public delegate void DelegateClass<T>(T data);
public class Starter {
public static void Main() {
DelegateClass<string> del = MethodA;
del("data");
}
public static void MethodA(string data) {
Console.WriteLine("MethodA ({0})", data);
}
}
</source>

==A simple generic delegate==

<source lang="csharp">
using System;
// Declare a generic delegate.
delegate T GenericDelegate<T>(T v);
class GenDelegateDemo {
static int sum(int v) {
int result = 0;
for(int i=v; i>0; i--)
result += i;
return result;
}
static string reflect(string str) {
string result = "";
foreach(char ch in str)
result = ch + result;
return result;
}
public static void Main() {
GenericDelegate<int> intDel = sum;
Console.WriteLine(intDel(3));
GenericDelegate<string> strDel = reflect;
Console.WriteLine(strDel("Hello"));
}
}

</source>

==Convert event to use generic delegate==

<source lang="csharp">
/*
Example code from

Chapter 18 - Generics
C# 2.0: The Complete Reference, Second Edition
by Herbert Schildt
McGraw-Hill/Osborne ? 2006
*/

using System;
class MyEventArgs : EventArgs {
public int eventnum;
}
delegate void MyEventHandler<T, V>(T source, V args);
class MyEvent {
static int count = 0;
public event MyEventHandler<MyEvent, MyEventArgs> SomeEvent;
public void OnSomeEvent() {
MyEventArgs arg = new MyEventArgs();
if(SomeEvent != null) {
arg.eventnum = count++;
SomeEvent(this, arg);
}
}
}
class X {
public void handler<T, V>(T source, V arg) where V : MyEventArgs {
Console.WriteLine("Event " + arg.eventnum + " received by an X object.");
Console.WriteLine("Source is " + source);
Console.WriteLine();
}
}
class Y {
public void handler<T,V>(T source, V arg) where V : MyEventArgs {
Console.WriteLine("Event " + arg.eventnum + " received by a Y object.");
Console.WriteLine("Source is " + source);
Console.WriteLine();
}
}
class Test {
public static void Main() {
X ob1 = new X();
Y ob2 = new Y();
MyEvent evt = new MyEvent();
evt.SomeEvent += ob1.handler;
evt.SomeEvent += ob2.handler;
evt.OnSomeEvent();
evt.OnSomeEvent();
}
}

</source>

==Generic Anonymous Methods==

<source lang="csharp">
public delegate void ADelegate<T>(T tvalue);
public class MyClass{
public void MethodA() {
ADelegate<int> del=delegate(int var) {
};
}
}
public class YClass<T>{
public delegate void BDelegate(T tValue);
public void MethodA() {
BDelegate del=delegate(T tValue) {
};
}
}
</source>

==Generic Delegate and non-generic delegate==

<source lang="csharp">
using System;
using System.Collections.Generic;
using System.Text;
public delegate void MyGenericDelegate<T>(T arg);
public delegate void MyDelegate(object arg);
class Program {
static void Main(string[] args) {
MyDelegate d = new MyDelegate(MyTarget);
d("More string data");
MyDelegate d2 = new MyDelegate(MyTarget);
d2(9);
MyGenericDelegate<string> strTarget =
new MyGenericDelegate<string>(StringTarget);
strTarget("Some string data");
MyGenericDelegate<int> intTarget = IntTarget;
intTarget(9);
Console.ReadLine();
}
static void MyTarget(object arg) {
if (arg is int) {
int i = (int)arg;
Console.WriteLine("++arg is: {0}", ++i);
}
if (arg is string) {
string s = (string)arg;
Console.WriteLine("arg in uppercase is: {0}", s.ToUpper());
}
}
static void StringTarget(string arg) {
Console.WriteLine("arg in uppercase is: {0}", arg.ToUpper());
}
static void IntTarget(int arg) {
Console.WriteLine("++arg is: {0}", ++arg);
}
}
</source>

==Generics and Delegates==

<source lang="csharp">
using System;
public delegate void DelegateClass(int data);
public class Starter {
public static void Main() {
DelegateClass del1 = MethodA<int>;
del1(5);
DelegateClass del2 = MethodA;
del1(10); // inferred
}
public static void MethodA<T>(T data) {
Console.WriteLine("MethodA ({0})", data);
}
}
</source>

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в 15:31, 26 мая 2010

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