In prior versions of C# once a named argument was used all subsequent arguments had to be named.

This can be quite restrictive in some scenarios, such as when wanting to specify the name for boolean arguments for clarification but not wanting to name all subsequent more obvious arguments.

Code

Now

UpdateOrderStatus(orderId, shipped: true, trackingId);

Before

UpdateOrderStatus(orderId, shipped: true, tracking: trackingId);

Notes

• A named argument can only be followed by positional arguments when it is in its correct position in the method signature.

More information

• C# Programming Guide
• Non-trailing arguments @ Gunnar Peipman blog