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C# delegate keyword is derived form which namespace?

Posted By :Abhisek Panda     Posted Date :December 28, 2009    Points :10   Category :C# 
C# delegate keyword is derived form System.MulticastDelegate.

You can also find related Interview Question to C# delegate keyword is derived form which namespace?  below: 

In Which NameSpace 'Content' Controls are derived from?

  
'Content' Controls are derived from System.Windows.Controls.ContentControl (More...)

What is Active Directory? What is the namespace used to access the Microsoft Active Directories? What are ADSI Directories?

  
Active Directory Service Interfaces (ADSI) is a programmatic interface for Microsoft Windows Active Directory. It enables your applications to interact with diverse directories on a network, using a single interface. Visual Studio .NET and the .NET Framework make it easy to add ADSI functionality with the DirectoryEntry and DirectorySearcher components.

Using ADSI, you can create applications that perform common administrative tasks, such as backing up databases, accessing printers, and administering user accounts. (More...)

What is the difference between a namespace and an assembly name?

  
A namespace is a logical naming scheme for types in which a simple type name, such as MyType, is preceded with a dot-separated hierarchical name. Such a naming scheme is completely under the control of the developer. For example, types MyCompany.FileAccess.A and MyCompany.FileAccess.B might be logically expected to have functionality related to file access. The .NET Framework uses a hierarchical naming scheme for grouping types into logical categories of related functionality, such as the ASP.NET application framework, or remoting functionality. Design tools can make use of namespaces to make it easier for developers to browse and reference types in their code. The concept of a namespace is not related to that of an assembly. A single assembly may contain types whose hierarchical names have different namespace roots, and a logical namespace root may span multiple assemblies. In the .NET Framework, a namespace is a logical design-time naming convenience, whereas an assembly establishes the name scope for types at run time.

Application Deployment and Isolation (More...)

Define namespace in C++ ?

  
It is a feature in c++ to minimize name collisions in the global name space. This namespace keyword assigns a distinct name to a library that allows other libraries to use the same identifier names without creating any name collisions. Furthermore, the compiler uses the namespace signature for differentiating the definitions. (More...)

What is the difference between a namespace and an assembly name?

  
A namespace is a logical naming scheme for types in which a simple type name, such as MyType, is preceded with a dot-separated hierarchical name. Such a naming scheme is completely under the control of the developer. For example, types MyCompany.FileAccess. A and MyCompany.FileAccess.B might be logically expected to have functionality related to file access. The .NET Framework uses a hierarchical naming scheme for grouping types into logical categories of related functionality, such as the Microsoft ASP.NET application framework, or remoting functionality. Design tools can make use of namespaces to make it easier for developers to browse and reference types in their code. The concept of a namespace is not related to that of an assembly. A single assembly may contain types whose hierarchical names have different namespace roots, and a logical namespace root may span multiple assemblies. In the .NET Framework, a namespace is a logical design-time naming convenience, whereas an assembly establishes the name scope for types at run time.

Shashi Ray (More...)

the difference between a delegate and an event

  
the difference between a delegate and an event

Hi


Here is the difference between a delegate and an event.

Delegate:

public class VikramDel

{

public delegate void VikramExampleDelegate(int num1,string str1);

public VikramExampleDelegate VikramDeleageteCallback;

}

Event:

public class VikramEvent

{

public delegate void VikramExampleEvent(int num1,string str2);

public event VikramExampleEvent VikramEventCallback;

}

So syntax wise there is only one difference that we have to use the event keyword with the event.

So the question comes why do we have a keyword when the same work can be done without using it. But there is a reason for the existence of the keyword event. Lets take an example how would a client work with this class

VikramDel V = new VikramDel();

V.VikramDeleageteCallback +=new

VikramDel.VikramExampleDelegate (this.VikDelegate);

Here we are adding a new target to the invocation list of the delegate. The same code will work with the other class also without any problem

VikramEvent V = new VikramEvent();

V.VikramEventCallback + =new

VikramEvent.VikramExampleEvent(this.VikDelegate);

But consider a case where by instead of adding a new target to the invocation list of the delegate if I simply set a delegate to a new delegate (The difference is with the + sign being not there).

VikramDel V = new VikramDel();

V.VikramDeleageteCallback =new

VikramDel.VikramExampleDelegate (this.VikDelegate);

This code will work fine here but the same will not work with an event.

So what it means is that if we use the event keyword no client class can set it to null. This is very important. Multiple clients can use the same delegate. After multiple client have added a function to listen to the callback of the delegate. But now one of the client sets the delegate to null or uses the = sign to add a new call back. This means that the previous invocation list will not be used any more. Hence all the previous client will not get any of the callback even if they have registered for the call back.

Hence we can say that the even keyword adds a layer of protection on the instance of the delegate. The protection prevents any client to reset the delegate invocation list. They can only add or remove the target from the invocation list. (More...)

Yield keyword in C Sharp

  
C Sharp and yield keyword

Hi,



One of the cool and yet most unknown feature of the C# is the yield keyword. The yield keyword is used in an iterator block to provide a value to the enumerator object or to signal the end of the iteration. When used the expression is evaluated and returned as a value to the enumerator object. Note the expression has to be implicitebly convertible to yield type of the iterator. Here is an example



public static IEnumerable GetIntCollectionFromString(string SomeString){ string[] val = SomeString.Split(' '); int intToAdd; foreach (string token in val) { if (int.TryParse(token, out intVal)) { yield return intVal; } else { yield break; } }}

Here since we are using the yield keyword the function will return the collection of intVal instead of the value of intVal. The statement will only return when the iteration of the loop is complete.



There are some limitation with the yield keywords.

Unsafe blocks are not allowed
Parameters to the method, operator, or accessor cannot be ref or out. (More...)

What is NameSpace?

  
Namespace has two basic functionality :-
NameSpace Logically group types, example System.Web.UI logically groups our UI related features.

In Object Oriented world many times its possible that programmers will use the same class name.By qualifying NameSpace with classname this collision is able to be removed. (More...)

What is Difference between NameSpace and Assembly?

  
Assembly is physical grouping of logical units. Namespace logically groups classes.

Namespace can span multiple assembly. (More...)

What is the difference between Namespace and Assembly?

  
Namespace:
1. It is a Collection of names wherein each name is Unique.
2. They form the logical boundary for a Group of classes.
3. Namespace must be specified in Project-Properties.

Assembly:
1. It is an Output Unit. It is a unit of Deployment & a unit of versioning. Assemblies contain MSIL code.
2. Assemblies are Self-Describing. [e.g. metadata,manifest]
3. An assembly is the primary building block of a .NET Framework application. It is a collection of functionality that is built, versioned, and deployed as a single implementation unit (as one or more files). All managed types and resources are marked either as accessible only within their implementation unit, or by code outside that unit. (More...)

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