JetBrains Rider 2023.3 Help

Code Inspection: Arrange null checking pattern

When checking an expression for null with the type-testing 'is' operator, you can choose between two null-checking patterns:

  • Use the 'not null' pattern that makes the expression more readable.

  • Use the object pattern syntax `{ }` that makes the expression more flexible, allowing you to declare a local variable after it.

public static void Test(object? obj) { if (obj is not null) Console.WriteLine("not null"); }
public static void Test(object? obj) { if (obj is { }) Console.WriteLine("not null"); }

By default, JetBrains Rider highlights object pattern syntax { } in null-checking expressions and suggests replace them with the not null pattern:

JetBrains Rider syntax style inspection: Use 'not null' pattern

If you prefer to use the { } pattern, you can change the corresponding preferences and JetBrains Rider will help you replace not null patterns accordingly:

JetBrains Rider syntax style inspection: Use '{ }' pattern

For more information, refer to Code Syntax Style: Null checking pattern.

Last modified: 27 February 2024