JetBrains Rider 2018.3 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 the solution-wide inspection is enabled, JetBrains Rider will detect that Name and Age 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 either or both of the following:

  • The simplified global usage checking is enabled — 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).

  • The solution-wide analysis is enabled — Enable solution-wide analysis on the Editor | Inspection Settings page of JetBrains Rider settings (Ctrl+Alt+S).

Note that even if a symbol has no direct usages in your solution and JetBrains Rider warns you about it, there could be cases where symbols are used indirectly — e.g. via reflection — or they could just be designed as public API. In all those cases you would want to suppress the usage-checking inspection for the symbol in question, and there are several ways to do so:

Last modified: 17 January 2019

See Also