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

1.5. Rename All Instances of Any Program Element

Symbolic rename




allows you to rename all instances of any element you declare in your
program, from classes and interfaces to properties and methods, in a
single step. This technique, which is decidedly not a simple text
search-and-replace feature by virtue of its awareness of program
syntax, solves many knotty problems found in previous releases of
Visual Basic. For example, imagine you want to rename a public
property named FirstName. If you use
search-and-replace, you'll also inadvertently affect
a text box named txtFirstName, an event handler
named cmdFirstName_Click, a database field
accessed through row("FirstName"), and even your
code comments. With symbolic rename, the IDE takes care of renaming
just what you want, and it completes all of its work in a single
step.

Note: Need to rename a method, property, or variable without
mangling other similar names in the same file? Visual Studio 2005
includes the perfect antidote to clumsy
search-and-replace.

1.5.1. How do I do that?

You can use symbolic rename from any code window. To understand how
it works, create a form that has a single text box named
TextBox1 and a button named
cmdText. Finally, add the form code in Example 1-2.

Example 1-2. A simple form that uses the word "Text" heavily

Public Class TextTest
Private Sub TextTest_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load
' Get the text from the text box.
Dim Text As String = TextBox1.Text
' Convert and display the text.
Text = ConvertText(Text)
MessageBox.Show("Uppercase Text is: " & Text)
End Sub
Public Function ConvertText(ByVal Text As String) As String
Return Text.ToUpper( )
End Function
End Class

This code performs a relatively mundane task: converting a
user-supplied string to uppercase and displays it in a message box.
What's notable is how many places it uses the word
"Text." Now, consider what happens
if you need to rename the local variable Text in
the event handler for the Form.Load event.
Clearly, this is enough to confuse any search-and-replace algorithm.
That's where symbolic rename comes in.

To use symbolic rename, simply right-click on the local
Text variable, and select Rename from the context
menu. In the Rename dialog box, enter the new variable name
LocalText and click OK. All the appropriate
instances in your code will be changed automatically without
affecting other elements in your code (such as the text box, the
comments, the literal text string, the form class name, the
Text parameter in the
ConvertText function, and so on).
Here's the resulting code:

Public Class TextTest
Private Sub cmdTest_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles cmdText.Click
' Get the text from the text box.
Dim LocalText As String = TextBox1.Text
' Convert and display the text.
LocalText = ConvertText(LocalText)
MessageBox.Show("Uppercase Text is: " & LocalText)
End Sub
Public Function ConvertText(ByVal Text As String) As String
Return Text.ToUpper( )
End Function
End Class

Symbolic rename works with any property, class, or method name you
want to change. Here are a few important points to keep in mind about
how symbolic rename works:

If you rename a class, all the statements that create an instance of
that class are also changed.

If you rename a method, all the statements that call that method are
also changed.

If you change a variable name that is the same as a method name, only
the variable is changed (and vice versa).

If you change a local variable name that is the same as a local
variable name with different scope (for example, in another method),
only the first variable is affected.

The symbolic rename feature isn't immediately
impressive, but it's genuinely useful. Particularly
noteworthy is the way it properly observes the scope of the item you
want to rename. For example, when you rename a local variable, your
changes don't spread beyond the current procedure.
On the other hand, renaming a class can affect every file in your
project.

Note that if you change the name of a control variable, your code
will also be updated accordingly. However, there's
one exceptionthe names of event handlers are never modified
automatically. For example, if you change Button1
to Button2, all the code that interacts with
Button1 will be updated, but the event handler
subroutine Button1_Click will not be affected.
(Remember, the name of the event handler has no effect on how it
works in your application, as long as it's connected
with the Handles clause.)

Tip:

In Visual Studio
2005, when you rename a .vb file in the Solution
Explorer, the name of the class in the file is also renamed, as long
as the file contains a class that has the old name. For example, if
you rename Form1.vb to
Form2.vb and the file contains a class named
Form1, that class will be renamed to
Form2. Any code statements that create an instance
of Form1 will also be updated, no matter where
they reside in the project. However, if you've
already changed the class name to something else (like
MyForm), the class name won't be
affected when you rename the file. In Visual Studio 2002 and 2003,
the same action of renaming a form file has no effect on your code,
so it's worth noting.

1.5.2. What about...

...support in Visual Basic 2005 for C#
refactoring? Unfortunately, many of the additional refactoring
features that Visual Studio provides to C# programmers
don't appear in Visual Basic at all. Symbolic rename
is one of the few new refactoring features that's
alive and well for VB programmers in this release.