ReSharper 2023.2 Help

Make fields readonly

It is often reasonable to use the 'readonly' modifier for fields that are assigned in the declaration or in a constructor and only have read usages. By default, ReSharper suggests that you make a field readonly if the above conditions are met. It highlights such fields and suggests the corresponding quick-fix or fix in scope:

Make field readonly quick-fix

If you do not want ReSharper to suggest this, you can disable the code inspection that detects it (Field can be made readonly).

The reverse functionality is also available. If you decide to change a readonly field later in your code (which leads to a compiler error), ReSharper detects the error and suggests fixing it by removing the 'readonly' keyword from the field:

Make non-readonly fix

Another option to make fields readonly in a bulk mode is code cleanup. You can either run code cleanup with the Built-in: Full Cleanup profile or create and run a custom profile solely targeted at your specific task as described below.

Add the 'readonly' keyword to fields that only have read access

  1. Select ReSharper | Options from the main menu or press Alt+R O.

  2. Go to the cleanup profiles settings page: Code Editing | Code Cleanup | Profiles.

  3. Create a new profile as described in the Create a new custom cleanup profile section. In the Selected profile settings section for the new profile, tick the Make field read-only, if possible checkbox. Optionally, you can enable other code cleanup tasks in this profile.

  4. Click Save in the Options dialog to apply the modifications and let ReSharper choose where to save them, or save the modifications to a specific settings layer using the Save To list. For more information, refer to manage and share resharper settings.

  5. Select the scope where you want to make fields readonly:

    • Place the caret anywhere in the file to make fields readonly to the file.

    • Select one or more items in the Solution Explorer to make fields readonly in the files under these nodes and their child items.

  6. Do one of the following:

    • Press Control+Alt+F or choose ReSharper | Edit | Cleanup Code… from the main menu .

    • Right-click anywhere in the text editor or right-click the selection and choose Cleanup Code in the context menu.

  7. In the Code Cleanup dialog that opens, select the newly created profile .

  8. Click Run. ReSharper will make fields readonly in the selected scope.

If you want to make fields readonly without opening the Code Cleanup dialog to choose a profile, you can bind the created profile to the silent cleanup and run it by pressing Control+Shift+Alt+F. You can also create a custom cleanup profile that would combine making fields readonly with other code style tasks.

This feature is supported in the following languages and technologies:

Language: C#

Language: VB.NET

Language: C++

Language: HTML

Language: ASP.NET

Language: Razor

Language: JavaScript

Language: TypeScript

Language: CSS

Language: XML

Language: XAML

Language: Resx

Language: Build Scripts

Language: Protobuf

Language: JSON

Feature is available in C#

Feature is not available in Visual Basic

Feature is not available in C++

Feature is not available in HTML

Feature is not available in ASP.NET

Feature is not available in Razor

Feature is not available in JavaScript

Feature is not available in TypeScript

Feature is not available in CSS

Feature is not available in XML

Feature is not available in XAML

Feature is not available in Resource files

Feature is not available in build script files

Feature is not available in Protobuf

Feature is not available in JSON

Last modified: 05 September 2023