Csharp/CSharp Tutorial/delegate/Multi cast delegate — различия между версиями
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Текущая версия на 12:19, 26 мая 2010
Содержание
Demonstrate multicasting
Create an invocation list, or chain, of methods that will be called when a delegate is invoked.
using System;
delegate string StrMod(ref string str);
class MultiCastDemo {
static string replaceSpaces(ref string a) {
Console.WriteLine("replaceSpaces");
return a;
}
static string removeSpaces(ref string a) {
Console.WriteLine("removeSpaces");
return a;
}
static string reverse(ref string a) {
Console.WriteLine("reverseSpaces");
return a;
}
public static void Main() {
StrMod strOp;
StrMod replaceSp = new StrMod(replaceSpaces);
StrMod removeSp = new StrMod(removeSpaces);
StrMod reverseStr = new StrMod(reverse);
string str = "This is a test";
// Set up multicast.
strOp = replaceSp;
strOp += reverseStr;
// Call multicast.
strOp(ref str);
// Remove replace and add remove.
strOp -= replaceSp;
strOp += removeSp;
str = "This is a test."; // reset string
// Call multicast.
strOp(ref str);
}
}
replaceSpaces reverseSpaces reverseSpaces removeSpaces
Multicast delegates
using System;
class MainClass
{
delegate int MyDelegate(string s);
static void Main(string[] args)
{
string MyString = "Hello World";
MyDelegate Multicast = null;
Multicast += new MyDelegate(DoSomething);
Multicast += new MyDelegate(DoSomething2);
Multicast(MyString);
}
static int DoSomething(string s)
{
Console.WriteLine("DoSomething");
return 0;
}
static int DoSomething2(string s)
{
Console.WriteLine("DoSomething2");
return 0;
}
}
DoSomething DoSomething2
Remove delegate from Multicast
using System;
class MainClass
{
delegate int MyDelegate(string s);
static void Main(string[] args)
{
string MyString = "Hello World";
//Or you can Multicast delegates by doing this
MyDelegate Multicast = null;
Multicast += new MyDelegate(DoSomething);
Multicast += new MyDelegate(DoSomething2);
Multicast -= new MyDelegate(DoSomething2);
Multicast(MyString);
}
static int DoSomething(string s)
{
Console.WriteLine("DoSomething");
return 0;
}
static int DoSomething2(string s)
{
Console.WriteLine("DoSomething2");
return 0;
}
}
DoSomething
uses the reference parameter of a multicast delegate as a counter
using System;
public delegate void DelegateClass(int valCount, ref int refCount);
public class Counter {
public static void Main() {
DelegateClass del = (DelegateClass)AddOne + (DelegateClass)AddTwo + (DelegateClass)AddOne;
int valCount = 0;
int refCount = 0;
del(valCount, ref refCount);
Console.WriteLine("Value count = {0}", valCount); // 0
Console.WriteLine("Reference count = {0}",refCount); // 4
}
public static void AddOne(int valCount,ref int refCount) {
++valCount;
++refCount;
}
public static void AddTwo(int valCount,ref int refCount) {
valCount += 2;
refCount += 2;
}
}