关于[C# 9 Covariant Return Types]的摘要:
Just a quick note on a neat feature in C# 9 that will allow sub-classes to return a covariant return type… what?! Okay, it allows you to return a more specific, or narrower type.
原文地址: https://www.stevefenton.co.uk/2020/05/csharp-9-covariant-return-types/