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

1.8. Call Methods at Design Time

Although Visual Studio .NET
2003 included the Immediate window, you couldn't use
it to execute code at design time. Longtime VB coders missed this
feature, which was a casualty of the lack of a background compiler.
In Visual Studio 2005, this feature returns along with the return of
a background compiler.

Note: Need to try out a freshly written code routine? Visual
Studio 2005 lets you run it without starting your project.

1.8.1. How do I do that?

You can use the Immediate window to evaluate simple expressions, and
even to run subroutines in your code. To try out this technique, add
the following shared method to a class:

Public Shared Function AddNumbers(ByVal A As Integer, _
ByVal B As Integer) As Integer
Return A + B
End Sub

By making this a shared method, you ensure that it's
available even without creating an instance of the class. Now, you
can call it easily in the design environment.

By default, the Immediate window isn't shown at
design time. To show it, select Debug
Windows
Command from the menu.
Statements inside the Immediate window usually start with
? (a shorthand for Print, which instructs Visual
Studio to display the result). You can enter the rest of the
statement like any other line of code, with the benefit of
IntelliSense. Figure 1-11 shows an example in which
the Command window is used to run the shared method just shown.

Figure 1-11. Executing code at design time

When you execute a statement like the one shown in Figure 1-11, there will be a short pause while the
background compiler works (and you'll see the
message "Build started" in the
status bar). Then the result will appear.

Note: The expression evaluation in the beta release of Visual
Studio 2005 is a little quirky. Some evaluations
won't work, and will simply launch your application
without returning a result. Look for this to improve in future
builds.

1.8.2. Where can I learn more?

The MSDN help includes more information about supported expression
types at the index entry "expressions
about
expressions."