Declaring & Scope of delegates

[Malfunction]

Where do you usually declare delegates? I know they're declared outside classes but what scope do they have? Edited April 27, 2004 by Malfunction

[Nerseus]

Nothing can be declared outside of a Class...

 

A delegate has the "scope" of the class. If you declare the class and the delegate as public then they have, more or less, global scope. Meaning, any class would be able to create a delegate of that type.

 

-Nerseus

[Malfunction]

but here the delegate is declared outside of the class:

-------------------------------

public delegate void MyDelegate;

public class MyClass {

public event MyDelegate triggerMyDelegate;

}

-------------------------------

And can be used in any other class (of that namespace?) as well.

[wessamzeidan]

I think this can be done only if MyClass is an inner class

[Malfunction]

I think this can be done only if MyClass is an inner class

 

 

No because I'm using it constantly in my project and it currently contains no inner classes at all. Since the delegate uis turned ionto a class by the compiler it makes sence not to declare the delegate as part of a certain class.

As the delegate can be declared in any class and used (e.g. implemented as an event) in all other classes I was just wondering what the standard procedure for declaring delegates is:

When I'm using a delegate in 10 classes but only declare it in one of them it might be hard to find that one class that declares it. Also I don't know what impact the delegate has towards namespaces.

 

Maybe it's differentin VB ?

I'm pretty new to delegates but I know the code above is working just fine in my app.

[Nerseus]

My mistake - only coded delegates a few time, long ago and quickly forgot how :)

 

Delegates are basically "global". If you define your delegate outside of a namespace then it's truly global. If you define it inside of a namespace, you'll have to reference the namespace when declare an instance of the delegate.

 

For example, say you had ClassLibrary1:

using System;
public delegate void MyDelegate();
namespace ClassLibrary1
{
}

 

And ConsoleApplication1:

using System;
namespace ConsoleApplication1
{
class Class1
{
	[sTAThread]
	static void Main(string[] args)
	{
		MyDelegate mydelegate = new MyDelegate(test);
		mydelegate();
		Console.Read();
	}
	static void test()
	{
		Console.WriteLine("Hello World");
	}
}
}

 

This will work. Now if you change ClassLibrary1 to put the delegate inside of the namespace like so:

using System;
namespace ClassLibrary1
{
   public delegate void MyDelegate();
}

 

Now ConsoleApplication1 won't compile unless you give it the namespace of ClassLibrary1, as in:

using System;
namespace ConsoleApplication1
{
class Class1
{
	[sTAThread]
	static void Main(string[] args)
	{
		[b]ClassLibrary1.[/b]MyDelegate mydelegate = new [b]ClassLibrary1.[/b]MyDelegate(test);
		mydelegate();
		Console.Read();
	}
	static void test()
	{
		Console.WriteLine("Hello World");
	}
}
}

 

Obviously, this assumes the delegate is made public. If it were internal, for example, it wouldn't be accessible outside the project/assembly.

 

-Nerseus