generate 2d barcode vb.net n n n in Visual C#

Encoding PDF-417 2d barcode in Visual C# n n n

n n n
PDF417 Creator In Visual C#.NET
Using Barcode generator for Visual Studio .NET Control to generate, create PDF-417 2d barcode image in .NET applications.
www.OnBarcode.com
PDF 417 Recognizer In C#
Using Barcode decoder for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
A method can register its interest in the event . A method can unregister its interest in the event . Registered methods will be notified when the event occurs .
Paint Bar Code In Visual C#.NET
Using Barcode creation for Visual Studio .NET Control to generate, create barcode image in .NET framework applications.
www.OnBarcode.com
Bar Code Scanner In Visual C#.NET
Using Barcode reader for .NET framework Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Types can offer this functionality when defining an event because they maintain a list of the registered methods . When the event occurs, the type notifies all of the registered methods in the collection . The common language runtime s (CLR s) event model is based on delegates . A delegate is a type-safe way to invoke a callback method . Callback methods are the means by which objects receive the notifications they subscribed to . In this chapter, I ll be using delegates, but I won t fully explain all their details until 17, Delegates . To help you fully understand the way events work within the CLR, I ll start with a scenario in which events are useful . Suppose you want to design an e-mail application . When an e-mail message arrives, the user might like the message to be forwarded to a fax machine or a pager . In architecting this application, let s say that you ll first design a type, called MailManager, that receives the incoming e-mail messages . MailManager will expose an event called NewMail . Other types (such as Fax and Pager) may register interest in this event . When MailManager receives a new e-mail message, it will raise the event, causing the message to be distributed to each of the registered objects . Each object can process the message in any way it desires .
PDF 417 Printer In VS .NET
Using Barcode generator for ASP.NET Control to generate, create PDF 417 image in ASP.NET applications.
www.OnBarcode.com
Drawing PDF417 In VS .NET
Using Barcode drawer for .NET framework Control to generate, create PDF417 image in Visual Studio .NET applications.
www.OnBarcode.com
Part II Designing Types
PDF-417 2d Barcode Encoder In VB.NET
Using Barcode encoder for .NET Control to generate, create PDF 417 image in VS .NET applications.
www.OnBarcode.com
Barcode Encoder In Visual C#
Using Barcode creation for VS .NET Control to generate, create bar code image in Visual Studio .NET applications.
www.OnBarcode.com
When the application initializes, let s instantiate just one MailManager instance the application can then instantiate any number of Fax and Pager types . Figure 11-1 shows how the application initializes and what happens when a new e-mail message arrives .
QR-Code Encoder In C#.NET
Using Barcode printer for .NET framework Control to generate, create QR image in VS .NET applications.
www.OnBarcode.com
PDF 417 Encoder In C#
Using Barcode maker for Visual Studio .NET Control to generate, create PDF-417 2d barcode image in VS .NET applications.
www.OnBarcode.com
Fax #1 4
Linear Creation In C#
Using Barcode generator for Visual Studio .NET Control to generate, create 1D image in VS .NET applications.
www.OnBarcode.com
USS-93 Printer In C#.NET
Using Barcode maker for .NET framework Control to generate, create USS Code 93, USS 93 image in Visual Studio .NET applications.
www.OnBarcode.com
Pager #1
Draw ANSI/AIM Code 39 In None
Using Barcode generator for Microsoft Word Control to generate, create Code 3/9 image in Microsoft Word applications.
www.OnBarcode.com
QR Code JIS X 0510 Creator In None
Using Barcode drawer for Font Control to generate, create QR Code JIS X 0510 image in Font applications.
www.OnBarcode.com
MailManager
Decoding USS Code 39 In Visual C#.NET
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Bar Code Encoder In None
Using Barcode generation for Office Word Control to generate, create barcode image in Word applications.
www.OnBarcode.com
1. 2. 3. 4.
GS1 - 13 Generation In None
Using Barcode generation for Font Control to generate, create EAN / UCC - 13 image in Font applications.
www.OnBarcode.com
Creating Code 128 Code Set B In Java
Using Barcode drawer for Android Control to generate, create Code 128 Code Set B image in Android applications.
www.OnBarcode.com
A method in the Fax object registers interest with the MailManager s event. A method in the Pager object registers interest with the MailManager s event. A new mail message arrives at MailManager. The MailManager object fires the notification off to all the registered methods, which process the mail message as desired
Encode Code128 In Visual Basic .NET
Using Barcode maker for .NET framework Control to generate, create Code 128C image in .NET framework applications.
www.OnBarcode.com
PDF417 Recognizer In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
FIguRE 11-1 Architecting an application to use events
Here s how the application illustrated in Figure 11-1 works: The application initializes by constructing an instance of MailManager . MailManager offers a NewMail event . When the Fax and Pager objects are constructed, they register an instance method with MailManager s NewMail event so that MailManager knows to notify the Fax and Pager objects when new e-mail messages arrive . Now, when MailManager receives a new e-mail message (sometime in the future), it will raise the NewMail event, giving all of the registered methods an opportunity to process the new message in any way they want .
Designing a Type That Exposes an Event
There are many steps a developer must take in order to define a type that exposes one or more event members . In this section, I ll walk through each of the necessary steps . The MailManager sample application (which can be downloaded from http://wintellect.com) shows all of the source code for the MailManager type, the Fax type, and the Pager type . You ll notice that the Pager type is practically identical to the Fax type .
11 Events
Step #1: Define a type that will hold any additional information that should be sent to receivers of the event notification
When an event is raised, the object raising the event may want to pass some additional information to the objects receiving the event notification . This additional information needs to be encapsulated into its own class, which typically contains a bunch of private fields along with some read-only public properties to expose these fields . By convention, classes that hold event information to be passed to the event handler should be derived from System.EventArgs, and the name of the class should be suffixed with EventArgs . In this example, the NewMailEventArgs class has fields identifying who sent the message (m_from), who is receiving the message (m_to), and the subject of the message (m_subject) .
// Step #1: Define a type that will hold any additional information that // should be sent to receivers of the event notification internal class NewMailEventArgs : EventArgs { private readonly String m_from, m_to, m_subject; public NewMailEventArgs(String from, String to, String subject) { m_from = from; m_to = to; m_subject = subject; } public String From { get { return m_from; } } public String To { get { return m_to; } } public String Subject { get { return m_subject; } } }
Copyright © OnBarcode.com . All rights reserved.