Question Delegate Confusion

[ishtarsg]

Hi
I am quite confuse with Delegate
I see some examples like
public delegate string FirstDelegate (int x);

class DelegateTest
{
string name;

static void Main()
{
FirstDelegate d1 = new FirstDelegate(DelegateTest.StaticMethod);

DelegateTest instance = new DelegateTest();
instance.name = "My instance";
FirstDelegate d2 = new FirstDelegate(instance.InstanceMethod);

Console.WriteLine (d1(10)); // Writes out "Static method: 10"
Console.WriteLine (d2(5)); // Writes out "My instance: 5"
}

static string StaticMethod (int i)
{
return string.Format ("Static method: {0}", i);
}

string InstanceMethod (int i)
{
return string.Format ("{0}: {1}", name, i);
}
}

However i failed to see any advantage in using delegate. Why wouldn't someone write codes like. Wouldn't it be too troublesome to 'new' some other objects just to preform the same job?
static void Main()
{
//FirstDelegate d1 = new FirstDelegate(DelegateTest.StaticMethod);

//DelegateTest instance = new DelegateTest();
//instance.name = "My instance";
//FirstDelegate d2 = new FirstDelegate(instance.InstanceMethod);

Console.WriteLine (StaticMethod (10)); // Writes out "Static method: 10"
Console.WriteLine (InstanceMethod (5)); // Writes out "My instance: 5"
}

 

[JohnH]

Where the delegated method belongs is not relevant.

Delegates (C# Programming Guide)

A delegate is a type that represents references to methods

Delegates are used to pass methods as arguments to other methods

Delegates can be chained together; for example, multiple methods can be called on a single event.

 

[JohnH]

You also have some confusion about instance and static, this is not valid code:

Console.WriteLine (InstanceMethod (5)); // Writes out "My instance: 5"

compiler error:

An object reference is required for the non-static field, method, or property 'DelegateTest.InstanceMethod(int)'

Static Classes and Static Class Members (C# Programming Guide)
10.2.5 Static and instance members (C#)

Generally speaking, it is useful to think of static members as belonging to classes and instance members as belonging to objects (instances of classes).