Rename Refactoring (C#)

Rename is a refactoring feature in the Visual Studio integrated development environment (IDE) that provides an easy way to rename identifiers for code symbols such as fields, local variables, methods, namespaces, properties, and types. Rename can be used to change the names in comments and in strings and to change the declarations and calls of an identifier.

Rename refactoring is available from the following Visual Studio features:

Feature	Behavior of Refactoring in the IDE
Code Editor	In the Code Editor, rename refactoring is available when you position the cursor on certain types of code symbols. When the cursor is in this position, you can invoke the Rename command by typing the keyboard shortcut (CTRL + R, R), or by selecting the Rename command from a smart tag, shortcut menu, or the Refactor menu.
Class View	When you select an identifier in Class View, rename refactoring is available from the shortcut menu and Refactor menu.
Object Browser	When you select an identifier in Object Browser, rename refactoring is only available from the Refactor menu.
Property Grid of the Windows Forms Designer	In the Property Grid of the Windows Forms Designer, changing the name of a control will initiate a rename operation for that control. The Rename dialog box will not appear.
Solution Explorer	In Solution Explorer, a Rename command is available on the shortcut menu. If the selected source file contains a class whose class name is the same as the file name, you can use this command to simultaneously rename the source file and execute rename refactoring. For example, if you create a default Windows-based application and then rename Form1.cs to TestForm.cs, the source file name Form1.cs will change to TestForm.cs and the class Form1 and all references to that class will be renamed to TestForm. Note The Undo command (CTRL+Z) will only undo rename refactoring in the code and will not change the file name back to the original name. If the selected source file does not contain a class whose name is the same as the file name, the Rename command in Solution Explorer will only rename the source file and will not execute rename refactoring.

Rename Operations

When you execute Rename, the refactoring engine performs a rename operation specific for each code symbol, as described in the following table.

Code Symbol	Rename Operation
Field	Changes the declaration and usages of the field to the new name.
Local variable	Changes the declaration and usages of the variable to the new name.
Method	Changes the name of the method and all references to that method to the new name. Note When you rename an extension method, the rename operation propagates to all instances of the method that are in scope, regardless of whether the extension method is being used as a static method or an instance method. For more information, see Extension Methods (C# Programming Guide).
Namespace	Changes the name of the namespace to the new name in the declaration, all using statements, and fully qualified names. Note When renaming a namespace, Visual Studio also updates the Default Namespace property on the Application page of the Project Designer. This property cannot be reset by selecting Undo from the Edit menu. To reset the Default Namespace property value, you must modify the property in the Project Designer. For more information, see Application Page.
Property	Changes the declaration and usages of the property to the new name.
Type	Changes all declarations and all usages of the type to the new name, including constructors and destructors. For partial types, the rename operation will propagate to all parts.

To rename an identifier

1. Create a console application named RenameIdentifier, and then replace Program with the following example code.

   class ProtoClassA
   {
       // Invoke on 'MethodB'.
       public void MethodB(int i, bool b) { }
   }
   
   class ProtoClassC
   {
       void D()
       {
           ProtoClassA MyClassA = new ProtoClassA();
   
           // Invoke on 'MethodB'.
           MyClassA.MethodB(0, false);
       }
   }
   

2. Place the cursor on MethodB, either in the method declaration or the method call.

3. From the Refactor menu, select Rename. The Rename dialog box appears.

   You can also type the keyboard shortcut F2 to display the Rename dialog box.

   You can also right-click the cursor, point to Refactor on the context menu, and then click Rename to display the Rename dialog box.

4. In the New Name field, type MethodC.

5. Select the Search in Comments check box.

6. Click OK.

7. In the Preview Changes dialog box, click Apply.

To rename an identifier using smart tags

1. Create a console application named RenameIdentifier, and then replace Program with the following example code.

   class ProtoClassA
   {
       // Invoke on 'MethodB'.
       public void MethodB(int i, bool b) { }
   }
   
   class ProtoClassC
   {
       void D()
       {
           ProtoClassA MyClassA = new ProtoClassA();
   
           // Invoke on 'MethodB'.
           MyClassA.MethodB(0, false);
       }
   }
   

2. In the declaration for MethodB, type or backspace over the method identifier. A smart tag prompt will appear below this identifier.

   Note

   You can only invoke rename refactoring using smart tags at the declaration of an identifier.

3. Type the keyboard shortcut SHIFT+ALT+F10, and then press the DOWN ARROW to display the smart tag menu.

   -or-

   Move the mouse pointer over the smart tag prompt to display the smart tag. Then move the mouse pointer over the smart tag and click the DOWN ARROW to display the smart tag menu.

4. Select the Rename '<identifer1>' to '<identifier2>' menu item to invoke rename refactoring without a preview of the changes to your code. All references to <identifer1> will automatically be updated to <identifier2>.

   -or-

   Select the Rename with preview menu item to invoke rename refactoring with a preview of the changes to your code. The Preview Changes dialog box will appear.

Remarks

Renaming Implemented or Overridden Members

When you Rename a member that either implements/overrides or is implemented/overridden by members in other types, Visual Studio displays a dialog box that says the rename operation will cause cascading updates. If you click Continue, the refactoring engine recursively finds and renames all members in base and derived types that have implements/overrides relationships with the member being renamed.

The following code example contains members with implements/overrides relationships.

interface IBase
{
    void Method();
}
public class Base
{
    public void Method()
    { }
    public virtual void Method(int i)
    { }
}
public class Derived : Base, IBase
{
    public new void Method()
    { }
    public override void Method(int i)
    { }
}
public class C : IBase
{
    public void Method()
    { }
}

In the previous example, renaming C.Method() also renames Ibase.Method() because C.Method() implements Ibase.Method(). Next, the refactor engine recursively sees that Ibase.Method() is implemented by Derived.Method() and renames Derived.Method(). The refactor engine does not rename Base.Method(), because Derived.Method() does not override Base.Method(). The refactoring engine stops here unless you have Rename overloads checked in the Rename dialog box.

If Rename overloads is checked, the refactor engine renames Derived.Method(int i) because it overloads Derived.Method(), Base.Method(int i) because it is overridden by Derived.Method(int i), and Base.Method() because it is an overload of Base.Method(int i).

Renaming Properties of Anonymous Types

When you rename a property in anonymous types, the rename operation will propagate to properties in other anonymous types that have the same properties. The following examples illustrate this behavior.

var a = new { ID = 1};
var b = new { ID = 2};

In the preceding code, renaming ID will change ID in both statements because they have the same underlying anonymous type.

var companyIDs =
    from c in companylist
    select new { ID = c.ID, Name = c.Name};

var orderIDs =
    from o in orderlist
    select new { ID = o.ID, Item = o.Name};

In the preceding code, renaming ID will only rename one instance of ID because companyIDs and orderIDs do not have the same properties.

See Also

Reference

Anonymous Types (C# Programming Guide)

Concepts

Refactoring (C#)