Implicit/Explicit Typing
Using
implicitly typed local variables
(also known as
var
keyword)
introduced in C# 3.0 has become quite popular due to improved readability of the resulting code.
By default, ReSharper also encourages using of
var
keyword, but the preferences of its usage are flexibly configurable.
For example, you can opt for using explicit types in specific cases or everywhere.
In this topic:
Enforcing preferences of using 'var' keyword
ReSharper checks all local variables for compliance with your preferences and if they do not comply, ReSharper highlights such declarations and suggests the corresponding quick-fix or fix in scope.
By default, ReSharper's preferences say that 'var' keyword is preferred:
If you change your preference, ReSharper will help you to use explicit types:
Another option to enforce preferences of 'var' keyword usage in a bulk mode is code cleanup. You can either run code cleanup with the default profile Default: Full Cleanup or run the cleanup with a custom profile solely targeted at your specific task as described below.
To apply preferences of using 'var' keyword with code cleanup
- Open the Code Cleanup options: ReSharper | Options | Code Editing | Code Cleanup.
- Create a new profile as described in the Configuring Code Cleanup section. In the Selected profile settings section for the new profile tick the Enforce 'var' keyword usage settings check box.
- Click Save 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 drop-down list. For more information, see Managing and Sharing ReSharper Settings.
- Select the scope where you want to enforce your preferences:
- Do one of the following:
- In the Code Cleanup dialog box that opens, select the newly created profile in the Available Profiles area.
- Click Run. ReSharper will enforce your preferences in the selected scope.
If you want to enforce 'var' keyword usage setting without opening the Code Cleanup dialog box, you can bind the created profile to the silent cleanup and run it simply by pressing Ctrl+Shift+Alt+F. You can also create a custom cleanup profile that would combine applying the preferences with other code style tasks.
Configuring preferences of using 'var' keyword
Your 'var' keyword usage preferences are saved using the mechanism of shared settings. Among other things, this mechanism allows you to maintain different preferences for different solutions as well as to keep these preferences under a VCS and automatically share them with your team members.
To configure preferences of using 'var' keyword
- Go to ReSharper | Options | Code Editing | C# | Code Style.
- Modify settings in the 'var' usage in declarations category according to your coding practices/standards.
- The Notify with selectors in the right column allow you to set severity levels of code inspections detecting code that differs from your preferences.
- If you do not want ReSharper to check and enforce some preferences and to prevent code cleanup from enforcing selected preferences, you can disable them by setting their severity levels to Do not show.
- Click Save 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 drop-down list. For more information, see Managing and Sharing ReSharper Settings.
You can also change your preference of using 'var' keyword right in the editor, where a corresponding issue is highlighted:
To change preference of using 'var' keyword from the editor
- Set the caret to a code issue highlighted by a ReSharper's inspection.
- Press Alt+Enter or click on the action indicator to the left of the caret to open the action list.
- In the action list, choose Inspection "Use preferred 'var' style" | Configure code style and then select a desired preference:
- Your change will be saved using the smart save logic.
- If you need to save the modified style preference in a shared settings layer, click on the Configure code style menu item or press Enter when it is selected. ReSharper will open the Code Editing | C# | Code Style options page where you can modify your preference as needed, click Save To and then choose the desired settings layer.
This feature is supported in the following languages/technologies:
C# | VB.NET | C++ | HTML | ASPX | Razor | JavaScript | TypeScript | CSS | XML | XAML | RESX | Build Scripts | Protobuf | JSON |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
The instructions and examples given here address the use of the feature in C#. For details specific to other languages, see corresponding topics in the ReSharper by Language section. Specifically:
See Also
Procedures:
- Naming Style
- Navigating between Code Issues
- Finding Out What is Wrong with Your Code
- Code Formatting Rules
- File and Type Layout
- File Header Style
- Namespace Imports Assistance
- Implicit/Explicit Typing
- Using Auto-Properties
- Making Fields Readonly
- Attributes Style
- Arranging Modifiers
- Arranging Optional Member Qualifiers
- Reformatting XML Doc Comments
- Removing Code Redundancies