JetBrains Rider 2024.1 Help

Code inspection: Field can be made readonly (non-private accessibility)

Say you have decided to make a Person class, initialized only via the constructor, but with publicly available fields. You go ahead and implement the following:

public class Person { public string Name; public int Age; public Person(string name, int age) { Name = name; Age = age; } public override string ToString() => $"Name: {Name}, Age: {Age}"; }
Public Class Person Public Name As String Public Age As Integer Public Sub New(name As String, age As Integer) Me.Name = name Me.Age = age End Sub Public Overrides Function ToString() As String Return String.Format("Name: {0}, Age: {1}", Name, Age) End Function End Class

If solution-wide inspection is enabled, JetBrains Rider can detect that the fields are only being assigned in the constructor and offers to create an additional safeguard: by marking them readonly, we get to ensure that neither this class nor its users will inadvertently assign new values to these fields.

For the solution-wide inspection to work, you need to enable at least one of the following:

  • Simplified global usage checking: select Show unused non-private type members when solution-wide analysis is off on the Editor | Inspection Settings page of JetBrains Rider settings Ctrl+Alt+S.

  • Solution-wide analysis: select Enable solution-wide analysis on the Editor | Inspection Settings page of JetBrains Rider settings Ctrl+Alt+S.

Note that even if the reported field has no direct usages in your solution, there could be cases where it is used indirectly — for example, via reflection — or it could just be designed as public API. In all those cases, you would want to suppress the usage-checking inspection for the field in one of the following ways:

Last modified: 11 February 2024