Extract Property

• Jun 07, 2019
• 3 minutes to read

Moves the selected code to a new read-only property. Inserts the appropriate calling code into the source method or property.

Purpose

Extract Property is great when you find you have an expression that you are using a lot, as it will take a chunk of code and move it into a new read-only property. Turning an often-used expression into a property eliminates code duplication and makes the code easier to read.

Availability

Available from the context menu or via shortcuts:

• when one or more statements are selected.
• when an expression is selected.

Using the Intelligent Paste feature:

• When a qualifying code block is cut from a method or property and subsequently pasted inside a struct or class.

Note: availability is identical to Extract Method, with one additional constraint - the extracted block must not require any parameters, and must change only one local variable (which must be referenced after the selected block).

Notes

• You can choose the newly declared property’s location using the target picker (see Settings below).
• Immediately after Extract Property, Rename becomes enabled so you can provide an appropriate name for the extracted property.
• If you extract the right-hand side of an assignment, the Extract Property automatically suggests a property name based on the assignment’s left-hand side.

Tips

• If the extracted property’s return value is assigned to a variable that is referred but not changed later, you can use Inline Temp refactoring to replace occurrences of the variable with the extracted property call. This will eliminate a redundant local variable.
• The Extract Property refactoring can be automatically called by the Replace Temp with Query refactoring. Refer to documentation on the Replace Temp with Query refactoring for additional information.
• Extract Method and Introduce Local refactorings are similar to Extract Property in functionality.

Options

• You can choose whether the extracted property should be located above or below the source method or property or whether its position should be set manually with the target picker.
• You can specify whether the extracted expression should be embedded inside parentheses.
• You can control whether the Intelligent Paste feature is available.

Example

C#

private string Name;
private string GetName()
{
    return Name;
}
private string TestMethod()
{
    return │"Name:" + GetName();
}

VB.NET

Private Name As String

Private Function GetName() As String
    Return Name
End Function

Private Function TestMethod() As String
    Return │"Name: " + GetName()
End Sub

Result:

C#

private string Name;
private string GetName()
{
    return Name;
}
private string PropName
{
    get
    {
        return "Name:" + GetName();
    }
}
private string TestMethod()
{
    return PropName;
}

VB.NET

Private Name As String

Private Function GetName() As String
    Return Name
End Function

Private ReadOnly Property PropName() As String
    Get
        Return "Name: " + GetName()
    End Get
End Property

Private Function TestMethod() As String
    Return PropName
End Sub

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