JetBrains Rider 2024.1 Help

Code inspection: Use preferred style of 'new' expression when created type is evident

Starting with C# 9.0, you can create objects with the target-typed new operator without explicit type specification when the type can be inferred, that is List<string> _myList = new(); instead of List<string> _myList = new List<string>();.

Depending on the context, the optional type specification can either clutter your code with redundant information or, on the contrary, improve the readability.

This inspection controls code style preferences for object creation expressions when the created type is evident from usage, like in the following cases:

  • Initializers of fields/constants/properties/events private Test field = new()

  • Initializers of local variables when an explicit type is preferred Test local = new()

  • Return values of expression-bodied members public List <Test> M() => new()

  • Values within array initializer new Test[] { new(), new() }

  • Values within collection initializer new List <Test> { new(), new() }

  • Default parameter values void M(TestStruct arg = new()) { }

By default, JetBrains Rider highlights type specifications as redundant in evident cases and helps remove them:

JetBrains Rider syntax style inspection: Use target-typed new

If you prefer another style for the new operator in your code, you can change the corresponding preferences.

For more information, refer to Code Syntax Style: Object Creation ('new()' vs 'new T()')

Last modified: 11 February 2024