Local scope variable shadows member¶
ID: cs/local-shadows-member
Kind: problem
Security severity:
Severity: recommendation
Precision: high
Tags:
- maintainability
- readability
Query suites:
- csharp-security-and-quality.qls
Click to see the query in the CodeQL repository
Naming a local variable or parameter after an existing member in the same class is confusing. It could lead to accesses or assignments to the local variable that should have been to the corresponding member.
Recommendation¶
For clarity, it may be better to rename the local variable to avoid shadowing.
Example¶
In this example, the local variable title shadows the member field of the same name. This leads to a mistaken reference to title when assigning the message string. The reference should really have been to this.title.
using System.Windows.Forms;
class Bad
{
private string title;
private string name;
public void DisplayDetails()
{
var title = "Person Details";
var message = "Title: " + title + "\nName: " + name;
MessageBox.Show(message, title);
}
}
Example¶
In the revised example, the local variable has been renamed to boxTitle, and the assignment to message is updated accordingly.
using System.Windows.Forms;
class Good
{
private string title;
private string name;
public void DisplayDetails()
{
var boxTitle = "Person Details";
var message = "Title: " + title + "\nName: " + name;
MessageBox.Show(message, boxTitle);
}
}