Visual Basic 1002005 [A Developers Notebook] [Electronic resources] نسخه متنی

2.1. Use the My Objects to Program Common Tasks

The new
My objects provide easy access to various features
that developers often need but don't necessarily
know where to find in the sprawling .NET class library. Essentially,
the My objects offer one-stop shopping, with
access to everything from the Windows registry to the current network
connection. Best of all, the My object hierarchy
is organized according to use and is easy to navigate using Visual
Studio IntelliSense.

2.1.1. How do I do that?

There are seven first-level My objects. Out of
these, three core objects centralize functionality from the .NET
Framework and provide computer information. These include:

Note: Tired of hunting through the extensive . NET class library
in search of what you need? With the new My objects, you can quickly
find some of the most useful features . NET has to offer.

My.Computer

This object provides information about
the current computer, including its network connection, the mouse and
keyboard state, the printer and screen, and the clock. You can also
use this object as a jumping-off point to play a sound, find a file,
access the registry, or use the Windows clipboard.

My.Application

This object provides information about
the current application and its context, including the assembly and
its version, the folder where the application is running, the
culture, and the command-line arguments that were used to start the
application. You can also use this object to log an application
event.

My.User

This object provides information about
the current user. You can use this object to check the
user's Windows account and test what groups the user
is a member of.

Along with these three objects, there are another two objects that
provide default
instances. Default instances are objects that .NET creates
automatically for certain types of classes defined in your
application. They include:

My.Forms

This object provides a default instance of
each Windows form in your application. You can use this object to
communicate between forms without needing to track form references in
another class.

My.WebServices

This object provides a default proxy-class
instance for every web service. For example, if your project uses two
web references, you can access a ready-made proxy class for each one
through this object.

Finally, there are two other My objects that
provide easy access to the configuration settings and resources:

My.Settings

This object allows you to retrieve custom
settings from your application's XML configuration
file.

My.Resources

This
object allows you to retrieve
resourcesblocks of binary or text data
that are compiled into your application assembly. Resources are
typically used to store localized strings, images, and audio files.

Warning: Note that the My objects are influenced by the
project type. For example, when creating a web or console
application, you won't be able to use
My.Forms.

Some of the My classes are defined in the
Microsoft.VisualBasic.MyServices namespace, while
others, such as the classes used for the
My.Settings and My.Resources
objects, are created dynamically by Visual Studio 2005 when you
modify application settings and add resources to the current project.

To try out the My object, you can use Visual
Studio IntelliSense. Just type
My, followed by a period, and take a look at the
available objects, as shown in Figure 2-1. You can
choose one and press the period again to step down another level.

Figure 2-1. Browsing the My objects

To try a simple example that displays some basic information using
the My object, create a new console project. Then,
add this code to the Main( ) routine:

Console.WriteLine(My.Computer.Name)
Console.WriteLine(My.Computer.Clock.LocalTime)
Console.WriteLine(My.Application.CurrentDirectory)
Console.WriteLine(My.User.Identity.Name)

When you run this code, you'll see some output in
the console window, which shows the computer name, current time,
application directory, and user:

SALESSERVER
2005-10-1 8:08:52 PM
C:\Code\VBNotebook\1.07\MyTest\bin
MATTHEW

Warning:
The My object also has a
"dark side." Use of the
My object makes it more difficult to share your
solution with non-VB developers, because other languages, such as C#,
don't have the same feature.

2.1.2. Where can I learn more?

You can learn more about the My object and see
examples by looking up the "My
Object" index entry in the MSDN Help. You can also
learn more by examining some of this book's other
labs that use the My object. Some examples
include:

Using My.Application to retrieve details of your
program, such as the current version and the command-line parameters
used to start it (see the "Get Application
Information" lab in this chapter).

Using My.Resources to load images and other
resources from the application assembly (see the
"Use Strongly Typed Resources" lab
in this chapter).

Using My.Settings to retrieve application and user
settings (see the "Use Strongly Typed Configuration
Settings" lab in this chapter).

Using My.Forms to interact between application
windows (see the "Communicate Between
Forms" lab in Chapter 3).

Using My.Computer to perform file manipulation and
network tasks in Chapters 5 and 6.

Using My.User to authenticate the current user
(see the "Test Group Membership of the Current
User" lab in Chapter 6).